AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

On 09/27/2012 03:44 PM, Jim Thompson wrote:
AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson

How about a mag amp?

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

On Thu, 27 Sep 2012 18:00:10 -0400, Phil Hobbs
wrote:

On 09/27/2012 03:44 PM, Jim Thompson wrote:
AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson

How about a mag amp?

Cheers

Phil Hobbs

Chewing on some authentic Australian licorice, I almost choked ;-)

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

On 9/27/2012 3:44 PM, Jim Thompson wrote:
AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson




A long,long time ago in a place not so far away I used a transformer
made by Sola that had a matched resonant capacitor.

Tom

On Thu, 27 Sep 2012 18:22:58 -0400, Tom Biasi
wrote:

On 9/27/2012 3:44 PM, Jim Thompson wrote:
AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson




A long,long time ago in a place not so far away I used a transformer
made by Sola that had a matched resonant capacitor.

Tom

Will it fit in 1" x 1" ?:-)

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

On 9/27/2012 7:29 PM, Jim Thompson wrote:
On Thu, 27 Sep 2012 18:22:58 -0400, Tom Biasi
wrote:

On 9/27/2012 3:44 PM, Jim Thompson wrote:
AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson




A long,long time ago in a place not so far away I used a transformer
made by Sola that had a matched resonant capacitor.

Tom

Will it fit in 1" x 1" ?:-)

...Jim Thompson




Not hardly. And it was heavy too.

Tom

"Jim Thompson" wrote in message
...

On Thu, 27 Sep 2012 18:22:58 -0400, Tom Biasi
wrote:

On 9/27/2012 3:44 PM, Jim Thompson wrote:
AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson




A long,long time ago in a place not so far away I used a transformer
made by Sola that had a matched resonant capacitor.

Tom

Will it fit in 1" x 1" ?:-)

No, but that VR method marches on (for select applications).
http://www.generaltransformer.com/tr...ansformers.htm

On Thu, 27 Sep 2012 19:44:50 -0400, Tom Biasi
wrote:

On 9/27/2012 7:29 PM, Jim Thompson wrote:
On Thu, 27 Sep 2012 18:22:58 -0400, Tom Biasi
wrote:

On 9/27/2012 3:44 PM, Jim Thompson wrote:
AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson




A long,long time ago in a place not so far away I used a transformer
made by Sola that had a matched resonant capacitor.

Tom

Will it fit in 1" x 1" ?:-)

...Jim Thompson




Not hardly. And it was heavy too.

Tom

I remember them. Nice scheme if you stand the space/weight.

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

Jim Thompson wrote:

On Thu, 27 Sep 2012 18:22:58 -0400, Tom Biasi
wrote:


On 9/27/2012 3:44 PM, Jim Thompson wrote:

AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson




A long,long time ago in a place not so far away I used a transformer
made by Sola that had a matched resonant capacitor.

Tom


Will it fit in 1" x 1" ?:-)

...Jim Thompson
If your looking for a junk don't care 120V low current supply..

this works on the starting cycle and uses only a portion.. it kinds of
semi regulates, it's only good for low current..






120V AC ||
+-------+-------------+-||-GND
| | ||
| V
| -
0.1uf --- |
--- |
| |/
|---------+-| 2N5550
| |
| |
.-. |
2k | | |
| | +----------+
'-' | |+
| 500u --- |
=== --- .-.
GND | | |
| | | Your Load
=== '-'
GND |
|
===
GND
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)
Like I said, it's junk but it works, you can sim that ...

I think that was around 5 volts out..

Jamie

On Thu, 27 Sep 2012 12:44:00 -0700, Jim Thompson
wrote:

AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

Not sure exactly what you are looking for, but if you are
using caps to drop voltage I'm guessing this is a "cheap and
cheerful"-type application.

I use a super-simple regulator to drop "dead" 9V batteries
down to 1.5V to run various low-drain devices like clocks
and timers. It's just an NPN (2N3904, etc) with collector
from battery, and emitter driving load. Base "reference" is
a green LED to ground, with a selected resistor from base to
collector. Small enough to wire the whole works onto a 9V
battery clip. Lots of variations: More LEDs for higher
output voltage, Darlingtons for more sensitivity/higher
power, etc.

Forward-biased LEDs have super-sharp knees at low currents,
and the parts bins are full of them.

Best regards,


Bob Masta

DAQARTA v7.00
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
Frequency Counter, Pitch Track, Pitch-to-MIDI
FREE Signal Generator, DaqMusic generator
Science with your sound card!

On Fri, 28 Sep 2012 21:57:20 -0500, legg wrote:

On Thu, 27 Sep 2012 12:44:00 -0700, Jim Thompson
wrote:

AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson

Power level? Input range?

RL

0.8W, Input is 220VAC/50Hz full-wave-rectified.

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

On Thu, 27 Sep 2012 12:44:00 -0700, Jim Thompson
wrote:

AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson

Power level? Input range?

RL

On Fri, 28 Sep 2012 18:58:01 -0700, Jim Thompson
wrote:

On Fri, 28 Sep 2012 21:57:20 -0500, legg wrote:

On Thu, 27 Sep 2012 12:44:00 -0700, Jim Thompson
wrote:

AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson

Power level? Input range?

RL

0.8W, Input is 220VAC/50Hz full-wave-rectified.

...Jim Thompson

That's unfortunate, because a lot of tweaking with nonlinear
dielectrics can be done on the lower domestic voltage range. This
reduces the effect of varying input voltage and can reduce the brute
in the force. Also 800mW is a lot to ask of this technique. An ~ 1uF
630VDC/240Vac capacitor hasn't traditionally been considered as small,
consumes a considerable portion of your 1"x1" real estate, and might
only get you 500mW.

Maybe you should mess with a few more numbers, before examining
improvements in the technique? Also, be warned that this isn't a
circuit you can just slip into a pre-existing device that has other
biasing dependencies.

I like the non-simplistic self-oscillating DC-DC stuff. The off-shore
demonstrated capability to produce this circuitry for nothing is the
only upside. Might as well be happy....

RL

"Jim Thompson" wrote in
message ...
On Fri, 28 Sep 2012 21:57:20 -0500, legg wrote:

On Thu, 27 Sep 2012 12:44:00 -0700, Jim Thompson
wrote:

AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson

Power level? Input range?

RL

0.8W, Input is 220VAC/50Hz full-wave-rectified.

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

The capacitor must go between the AC line and input to the bridge. It uses
the reactance of the capacitor as a dropping resistor.

On Sat, 29 Sep 2012 07:18:57 -0500, "Rick"
wrote:


"Jim Thompson" wrote in
message ...
On Fri, 28 Sep 2012 21:57:20 -0500, legg wrote:

On Thu, 27 Sep 2012 12:44:00 -0700, Jim Thompson
wrote:

AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson

Power level? Input range?

RL

0.8W, Input is 220VAC/50Hz full-wave-rectified.

...Jim Thompson
[snip]

The capacitor must go between the AC line and input to the bridge. It uses
the reactance of the capacitor as a dropping resistor.


Nonsense, all it requires is a _changing_ input.

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

On Sat, 29 Sep 2012 18:54:28 -0500, legg wrote:

On Sat, 29 Sep 2012 08:44:22 -0700, Jim Thompson
wrote:

On Sat, 29 Sep 2012 07:18:57 -0500, "Rick"
wrote:


"Jim Thompson" wrote in
message ...
On Fri, 28 Sep 2012 21:57:20 -0500, legg wrote:

On Thu, 27 Sep 2012 12:44:00 -0700, Jim Thompson
wrote:

AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson

Power level? Input range?

RL

0.8W, Input is 220VAC/50Hz full-wave-rectified.

...Jim Thompson
[snip]

The capacitor must go between the AC line and input to the bridge. It uses
the reactance of the capacitor as a dropping resistor.


Nonsense, all it requires is a _changing_ input.

...Jim Thompson

With appropriate discharge paths. If the cap is before the rectifier,
the source can do this, otherwise........

RL

Or a PFC path... that's all I can say right now ;-)

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

On Thu, 27 Sep 2012 12:44:00 -0700, the renowned Jim Thompson
wrote:

AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson

If it's full-wave rectified you can turn a HV part 'off' when the
voltage exceeds your desired output voltage and lose the series cap.
Your output cap need only be as big as a full-wave rectified low
voltage supply would required.

The cap is better with transients most likely, but if it's behind a
bunch of electronics anyway, the above might be a good solution.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

On Sat, 29 Sep 2012 08:44:22 -0700, Jim Thompson
wrote:

On Sat, 29 Sep 2012 07:18:57 -0500, "Rick"
wrote:


"Jim Thompson" wrote in
message ...
On Fri, 28 Sep 2012 21:57:20 -0500, legg wrote:

On Thu, 27 Sep 2012 12:44:00 -0700, Jim Thompson
wrote:

AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson

Power level? Input range?

RL

0.8W, Input is 220VAC/50Hz full-wave-rectified.

...Jim Thompson
[snip]

The capacitor must go between the AC line and input to the bridge. It uses
the reactance of the capacitor as a dropping resistor.


Nonsense, all it requires is a _changing_ input.

...Jim Thompson

With appropriate discharge paths. If the cap is before the rectifier,
the source can do this, otherwise........

RL

legg wrote:

On Sat, 29 Sep 2012 16:01:51 -0700, Jim Thompson
wrote:


On Sat, 29 Sep 2012 18:54:28 -0500, legg wrote:


On Sat, 29 Sep 2012 08:44:22 -0700, Jim Thompson
wrote:


On Sat, 29 Sep 2012 07:18:57 -0500, "Rick"
wrote:


"Jim Thompson" wrote in
message ...

On Fri, 28 Sep 2012 21:57:20 -0500, legg wrote:


On Thu, 27 Sep 2012 12:44:00 -0700, Jim Thompson
wrote:


AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson

Power level? Input range?

RL

0.8W, Input is 220VAC/50Hz full-wave-rectified.

...Jim Thompson

[snip]

The capacitor must go between the AC line and input to the bridge. It uses
the reactance of the capacitor as a dropping resistor.


Nonsense, all it requires is a _changing_ input.

...Jim Thompson

With appropriate discharge paths. If the cap is before the rectifier,
the source can do this, otherwise........

RL

Or a PFC path... that's all I can say right now ;-)

...Jim Thompson


Who's on first.

RL
You know, Jim really shocks me, he designs IC's and yet, he has this dilemma

Getting information from him is like pulling teeth.. It would be nice
to know the output voltage requirement. We already know the watts (0.8),
but at what voltage on the output?

I offered up a bad idea of a design, just like him asking for
something that should be trivial on his part.

WHen he said a "Cap dropper" I miss read and gave him a "Crap dropper"
or did I?

The circuit I offered up however, works great as a line noise detector.

Jamie

On Sat, 29 Sep 2012 16:01:51 -0700, Jim Thompson
wrote:

On Sat, 29 Sep 2012 18:54:28 -0500, legg wrote:

On Sat, 29 Sep 2012 08:44:22 -0700, Jim Thompson
wrote:

On Sat, 29 Sep 2012 07:18:57 -0500, "Rick"
wrote:


"Jim Thompson" wrote in
message ...
On Fri, 28 Sep 2012 21:57:20 -0500, legg wrote:

On Thu, 27 Sep 2012 12:44:00 -0700, Jim Thompson
wrote:

AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson

Power level? Input range?

RL

0.8W, Input is 220VAC/50Hz full-wave-rectified.

...Jim Thompson
[snip]

The capacitor must go between the AC line and input to the bridge. It uses
the reactance of the capacitor as a dropping resistor.


Nonsense, all it requires is a _changing_ input.

...Jim Thompson

With appropriate discharge paths. If the cap is before the rectifier,
the source can do this, otherwise........

RL

Or a PFC path... that's all I can say right now ;-)

...Jim Thompson

Who's on first.

RL

On 2012-09-29, Jim Thompson wrote:
On Fri, 28 Sep 2012 21:57:20 -0500, legg wrote:

On Thu, 27 Sep 2012 12:44:00 -0700, Jim Thompson
wrote:

AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson

Power level? Input range?

RL

0.8W, Input is 220VAC/50Hz full-wave-rectified.

...Jim Thompson

you're wanting to run it off the ripple?
the higher frequency will help a bit, but the voltage swing will be
much less, less predictable too I expect.



--
š‚šƒ 100% natural

--- news://freenews.netfront.net/ - complaints: ---

On Sat, 29 Sep 2012 22:05:05 -0500, legg wrote:

On Sat, 29 Sep 2012 16:01:51 -0700, Jim Thompson
wrote:

On Sat, 29 Sep 2012 18:54:28 -0500, legg wrote:

On Sat, 29 Sep 2012 08:44:22 -0700, Jim Thompson
wrote:

On Sat, 29 Sep 2012 07:18:57 -0500, "Rick"
wrote:


"Jim Thompson" wrote in
message ...
On Fri, 28 Sep 2012 21:57:20 -0500, legg wrote:

On Thu, 27 Sep 2012 12:44:00 -0700, Jim Thompson
wrote:

AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson

Power level? Input range?

RL

0.8W, Input is 220VAC/50Hz full-wave-rectified.

...Jim Thompson
[snip]

The capacitor must go between the AC line and input to the bridge. It uses
the reactance of the capacitor as a dropping resistor.


Nonsense, all it requires is a _changing_ input.

...Jim Thompson

With appropriate discharge paths. If the cap is before the rectifier,
the source can do this, otherwise........

RL

Or a PFC path... that's all I can say right now ;-)

...Jim Thompson

Who's on first.

RL

Costello :-)

But that's the real problem: egg-chicken-egg... who runs the control
loop?

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

On Sat, 29 Sep 2012 23:56:07 -0500, the renowned flipper
wrote:


I used a variation of that to make a 12.6V (DC) tube heater supply
from a 30V transformer. I call it a "pulse regulator."

The series cap is still a good idea because the charge pulse is going
to be limited by 'something', even if it's only Rdson, and the cap
would cut down on the peak current spikes.

Then how about clamping the cap low side to ground after the output
filter cap has gotten enough juice? Need another series switch or
diode, of course. The power dissipation would be much less doing it
that way since i*Rds(on) should be Vout.



Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

On Sat, 29 Sep 2012 19:34:02 -0400, Spehro Pefhany
wrote:

On Thu, 27 Sep 2012 12:44:00 -0700, the renowned Jim Thompson
wrote:

AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson

If it's full-wave rectified you can turn a HV part 'off' when the
voltage exceeds your desired output voltage and lose the series cap.
Your output cap need only be as big as a full-wave rectified low
voltage supply would required.

The cap is better with transients most likely, but if it's behind a
bunch of electronics anyway, the above might be a good solution.


Best regards,
Spehro Pefhany

The series current-limiting cap dissipates no power, so it can be
shorted by a low voltage switch. If it drives, say, the input of a
bridge rectifier or a 2-diode restore thing, short the input of that.
It becomes a bang-bang regulator. If the controller is to be a custom
IC, a modest amount of complexity is free, so some intelligent
zero-crossing thing would be appropriate. But just dumb bang-bang
ought to work.


This is one variation:

https://dl.dropbox.com/u/53724080/Ci..._regulator.jpg

The first diode can be the fet's substrate diode, saving one part.

This is like an alternator regulator that shorts the alternator output
with a triac, to get regulation.

People often add a series resistor, for spike protection, and that
will dissipate some power, but no more than it would with a zener
shunt regulator.

On Sun, 30 Sep 2012 10:29:48 -0700, the renowned John Larkin
wrote:



The series current-limiting cap dissipates no power, so it can be
shorted by a low voltage switch. If it drives, say, the input of a
bridge rectifier or a 2-diode restore thing, short the input of that.
It becomes a bang-bang regulator. If the controller is to be a custom
IC, a modest amount of complexity is free, so some intelligent
zero-crossing thing would be appropriate. But just dumb bang-bang
ought to work.

Yup, that's pretty much what I had in mind, I don't think you need the
left diode- either the body diode or turning the MOSFET on will work
(assuming custom ICs are like discretes, which they may not be).

Making the other diode into a synchronous MOSFET rectifier might be
worth it.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

John Larkin wrote:

On Sat, 29 Sep 2012 19:34:02 -0400, Spehro Pefhany
wrote:


On Thu, 27 Sep 2012 12:44:00 -0700, the renowned Jim Thompson
wrote:


AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson

If it's full-wave rectified you can turn a HV part 'off' when the
voltage exceeds your desired output voltage and lose the series cap.
Your output cap need only be as big as a full-wave rectified low
voltage supply would required.

The cap is better with transients most likely, but if it's behind a
bunch of electronics anyway, the above might be a good solution.


Best regards,
Spehro Pefhany


The series current-limiting cap dissipates no power, so it can be
shorted by a low voltage switch. If it drives, say, the input of a
bridge rectifier or a 2-diode restore thing, short the input of that.
It becomes a bang-bang regulator. If the controller is to be a custom
IC, a modest amount of complexity is free, so some intelligent
zero-crossing thing would be appropriate. But just dumb bang-bang
ought to work.


This is one variation:

https://dl.dropbox.com/u/53724080/Ci..._regulator.jpg

The first diode can be the fet's substrate diode, saving one part.

This is like an alternator regulator that shorts the alternator output
with a triac, to get regulation.

People often add a series resistor, for spike protection, and that
will dissipate some power, but no more than it would with a zener
shunt regulator.


that looks just like a charging circuit I tried once, only I didn't have
a ripple cap. All I had was a - feed back zener and a bjt with a
by pass diode, at the time. I only used a 24V AC source but the idea was
to allow it to have a constant short with out internal heating.

I wanted a pulse type of charging instead of constant DC.







10u
600V SI 30 Hz pulse out
||
-||-+--+------+----+-|-+-+---------------------+
|| | | +
AC line in | | z Max Voltage limit Diode
| | A
| | |
surge clamp z | |
A + HV NPN V Back flow stopper
-(diode too) | | -
5 watt + \| |
| |+--------+-------+
| | .-. +
| + | | ---
| | | | ---
| | '+' +
+------+-----------++------+
|
===
GND
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

Even though that works, I wouldn't suggest using AC over 48 volts
unless you have it totally enclosed.

Never thought of trying a mosfet for that, I have seen some that have
zenering substrate diodes. Those can do the job of both the required
diode and the noise pulse that may exceed the fets voltage.

If I remember there was a little (-) voltage coming back through the
collector but it didn't seem to bother the rest of it.

Jamie

On 2012-09-30, John Larkin wrote:

The series current-limiting cap dissipates no power, so it can be
shorted by a low voltage switch. If it drives, say, the input of a
bridge rectifier or a 2-diode restore thing, short the input of that.
It becomes a bang-bang regulator. If the controller is to be a custom
IC, a modest amount of complexity is free, so some intelligent
zero-crossing thing would be appropriate. But just dumb bang-bang
ought to work.


This is one variation:

https://dl.dropbox.com/u/53724080/Ci..._regulator.jpg

inrush current will destroy it.



--
š‚šƒ 100% natural

--- news://freenews.netfront.net/ - complaints: ---

On 1 Oct 2012 06:00:24 GMT, Jasen Betts wrote:

On 2012-09-30, John Larkin wrote:

The series current-limiting cap dissipates no power, so it can be
shorted by a low voltage switch. If it drives, say, the input of a
bridge rectifier or a 2-diode restore thing, short the input of that.
It becomes a bang-bang regulator. If the controller is to be a custom
IC, a modest amount of complexity is free, so some intelligent
zero-crossing thing would be appropriate. But just dumb bang-bang
ought to work.


This is one variation:

https://dl.dropbox.com/u/53724080/Ci..._regulator.jpg

inrush current will destroy it.

As I mentioned, and you snipped, people often include a series
resistor to limit transient currents.

C-limited supplies are commonly used for things like LED night-lights.
It does take good engineering to do them right.

On Mon, 01 Oct 2012 08:34:46 -0700, John Larkin
wrote:

On 1 Oct 2012 06:00:24 GMT, Jasen Betts wrote:

On 2012-09-30, John Larkin wrote:

The series current-limiting cap dissipates no power,

---
Not quite true, since no dielectric is lossless.
---

so it can be shorted by a low voltage switch.

---
It can be but, depending on when in the cycle the switch turns on,
things might get grim.
---

If it drives, say, the input of a
bridge rectifier or a 2-diode restore thing, short the input of that.

---
Still, depending on when in the cycle the switch turns on, things
might get grim.
---

It becomes a bang-bang regulator. If the controller is to be a custom
IC, a modest amount of complexity is free, so some intelligent
zero-crossing thing would be appropriate. But just dumb bang-bang
ought to work.

---
From the ridiculous to the sublime to the ridiculous!
---

This is one variation:

https://dl.dropbox.com/u/53724080/Ci..._regulator.jpg

inrush current will destroy it.

As I mentioned, and you snipped, people often include a series
resistor to limit transient currents.

---
And yet your circuit shows that some people - who should know better -
don't.
---

C-limited supplies are commonly used for things like LED night-lights.

---
C = current?

Since resistors are way cheaper than caps, my feeling is that using
cheap 2mA LEDs in parallel opposition with a 1/4 watt resistor in
series with 120V mains will do the trick.

You?
---

It does take good engineering to do them right.

---
Then you don't make LED night-lights, I take it?

--
JF

On Mon, 01 Oct 2012 18:03:56 -0500, John Fields
wrote:

On Mon, 01 Oct 2012 08:34:46 -0700, John Larkin
wrote:

On 1 Oct 2012 06:00:24 GMT, Jasen Betts wrote:

On 2012-09-30, John Larkin wrote:

The series current-limiting cap dissipates no power,

---
Not quite true, since no dielectric is lossless.
---

so it can be shorted by a low voltage switch.

---
It can be but, depending on when in the cycle the switch turns on,
things might get grim.
---

If it drives, say, the input of a
bridge rectifier or a 2-diode restore thing, short the input of that.

---
Still, depending on when in the cycle the switch turns on, things
might get grim.

Bad engineering can create grim outcomes. Better to not do that.

---

It becomes a bang-bang regulator. If the controller is to be a custom
IC, a modest amount of complexity is free, so some intelligent
zero-crossing thing would be appropriate. But just dumb bang-bang
ought to work.

---
From the ridiculous to the sublime to the ridiculous!
---

This is one variation:

https://dl.dropbox.com/u/53724080/Ci..._regulator.jpg

inrush current will destroy it.

As I mentioned, and you snipped, people often include a series
resistor to limit transient currents.

---
And yet your circuit shows that some people - who should know better -
don't.


Idiot whining again. That's pretty much your skill set.


---

C-limited supplies are commonly used for things like LED night-lights.

---
C = current?

Idiot whining again.


Since resistors are way cheaper than caps, my feeling is that using
cheap 2mA LEDs in parallel opposition with a 1/4 watt resistor in
series with 120V mains will do the trick.

A 1/4 watt resistor dissipating 1/4 watt in a confined space won't
last long. At 240 volts, 2 mA dissipates a half watt.



You?
---

It does take good engineering to do them right.

---
Then you don't make LED night-lights, I take it?

What an ass you are.

I certainly don't make night lights for production. My stuff sells for
kilobucks, not cents. I have done a few for myself, for personal
applications.

I assume that JT has some commercial application in mind, with a low
vampire power budget, and has no ideas of his own.


--

John Larkin Highland Technology, Inc

jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser drivers and controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro acquisition and simulation

On Sun, 30 Sep 2012 17:21:30 -0400, Jamie
t wrote:

John Larkin wrote:

On Sat, 29 Sep 2012 19:34:02 -0400, Spehro Pefhany
wrote:


On Thu, 27 Sep 2012 12:44:00 -0700, the renowned Jim Thompson
wrote:


AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson

If it's full-wave rectified you can turn a HV part 'off' when the
voltage exceeds your desired output voltage and lose the series cap.
Your output cap need only be as big as a full-wave rectified low
voltage supply would required.

The cap is better with transients most likely, but if it's behind a
bunch of electronics anyway, the above might be a good solution.


Best regards,
Spehro Pefhany


The series current-limiting cap dissipates no power, so it can be
shorted by a low voltage switch. If it drives, say, the input of a
bridge rectifier or a 2-diode restore thing, short the input of that.
It becomes a bang-bang regulator. If the controller is to be a custom
IC, a modest amount of complexity is free, so some intelligent
zero-crossing thing would be appropriate. But just dumb bang-bang
ought to work.


This is one variation:

https://dl.dropbox.com/u/53724080/Ci..._regulator.jpg

The first diode can be the fet's substrate diode, saving one part.

This is like an alternator regulator that shorts the alternator output
with a triac, to get regulation.

People often add a series resistor, for spike protection, and that
will dissipate some power, but no more than it would with a zener
shunt regulator.


that looks just like a charging circuit I tried once, only I didn't have
a ripple cap. All I had was a - feed back zener and a bjt with a
by pass diode, at the time. I only used a 24V AC source but the idea was
to allow it to have a constant short with out internal heating.

I wanted a pulse type of charging instead of constant DC.







10u
600V SI 30 Hz pulse out
||
-||-+--+------+----+-|-+-+---------------------+
|| | | +
AC line in | | z Max Voltage limit Diode
| | A
| | |
surge clamp z | |
A + HV NPN V Back flow stopper
-(diode too) | | -
5 watt + \| |
| |+--------+-------+
| | .-. +
| + | | ---
| | | | ---
| | '+' +
+------+-----------++------+
|
===
GND
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

Even though that works, I wouldn't suggest using AC over 48 volts
unless you have it totally enclosed.

Never thought of trying a mosfet for that, I have seen some that have
zenering substrate diodes. Those can do the job of both the required
diode and the noise pulse that may exceed the fets voltage.

If I remember there was a little (-) voltage coming back through the
collector but it didn't seem to bother the rest of it.

Jamie

That looks equivalent to a shunt zener. The NPN runs in linear mode
and gets hot.




--

John Larkin Highland Technology, Inc

jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser drivers and controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro acquisition and simulation

On Tue, 02 Oct 2012 11:08:51 -0700, John Larkin
wrote:

[snip]

I assume that JT has some commercial application in mind, with a low
vampire power budget, and has no ideas of his own.

Yep, extremely low power, switcher start-up circuitry, and I certainly
do have ideas of my own: controlled surge, then, once switcher starts,
auxiliary supply is turned off _completely_, no capacitor current at
all... done with a readily available 15 cent part.

Students! What is the beginner's error in this...

https://dl.dropbox.com/u/53724080/Ci..._regulator.jpg ?:-)

Other than it being general Larkin crap ;-)

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

On Tue, 02 Oct 2012 17:47:20 -0400, Jamie
t wrote:

John Larkin wrote:
On Sun, 30 Sep 2012 17:21:30 -0400, Jamie
t wrote:


John Larkin wrote:


On Sat, 29 Sep 2012 19:34:02 -0400, Spehro Pefhany
wrote:



On Thu, 27 Sep 2012 12:44:00 -0700, the renowned Jim Thompson
wrote:



AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson

If it's full-wave rectified you can turn a HV part 'off' when the
voltage exceeds your desired output voltage and lose the series cap.
Your output cap need only be as big as a full-wave rectified low
voltage supply would required.

The cap is better with transients most likely, but if it's behind a
bunch of electronics anyway, the above might be a good solution.


Best regards,
Spehro Pefhany


The series current-limiting cap dissipates no power, so it can be
shorted by a low voltage switch. If it drives, say, the input of a
bridge rectifier or a 2-diode restore thing, short the input of that.
It becomes a bang-bang regulator. If the controller is to be a custom
IC, a modest amount of complexity is free, so some intelligent
zero-crossing thing would be appropriate. But just dumb bang-bang
ought to work.


This is one variation:

https://dl.dropbox.com/u/53724080/Ci..._regulator.jpg

The first diode can be the fet's substrate diode, saving one part.

This is like an alternator regulator that shorts the alternator output
with a triac, to get regulation.

People often add a series resistor, for spike protection, and that
will dissipate some power, but no more than it would with a zener
shunt regulator.



that looks just like a charging circuit I tried once, only I didn't have
a ripple cap. All I had was a - feed back zener and a bjt with a
by pass diode, at the time. I only used a 24V AC source but the idea was
to allow it to have a constant short with out internal heating.

I wanted a pulse type of charging instead of constant DC.







10u
600V SI 30 Hz pulse out
||
-||-+--+------+----+-|-+-+---------------------+
|| | | +
AC line in | | z Max Voltage limit Diode
| | A
| | |
surge clamp z | |
A + HV NPN V Back flow stopper
-(diode too) | | -
5 watt + \| |
| |+--------+-------+
| | .-. +
| + | | ---
| | | | ---
| | '+' +
+------+-----------++------+
|
===
GND
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

Even though that works, I wouldn't suggest using AC over 48 volts
unless you have it totally enclosed.

Never thought of trying a mosfet for that, I have seen some that have
zenering substrate diodes. Those can do the job of both the required
diode and the noise pulse that may exceed the fets voltage.

If I remember there was a little (-) voltage coming back through the
collector but it didn't seem to bother the rest of it.

Jamie


That looks equivalent to a shunt zener. The NPN runs in linear mode
and gets hot.




Not really, the idea is to select the dropping cap to deliver only
what you need and the excess is shunted via the NPN. Excess being no load or
topped off battery after charge.

It does the same as a single zener, but is more complex.


Your use of a mosfet in the same place being regulated in linear mode
would also do the same,

No, my circuit goes into zero dissipation mode when it doesn't need to
charge the cap. The low-voltage shunt mosfet (or NPN) could be
integrated into a controller chip. Maybe Jim can patent the idea.


--

John Larkin Highland Technology, Inc

jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser drivers and controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro acquisition and simulation

John Larkin wrote:
On Sun, 30 Sep 2012 17:21:30 -0400, Jamie
t wrote:


John Larkin wrote:


On Sat, 29 Sep 2012 19:34:02 -0400, Spehro Pefhany
wrote:



On Thu, 27 Sep 2012 12:44:00 -0700, the renowned Jim Thompson
wrote:



AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson

If it's full-wave rectified you can turn a HV part 'off' when the
voltage exceeds your desired output voltage and lose the series cap.
Your output cap need only be as big as a full-wave rectified low
voltage supply would required.

The cap is better with transients most likely, but if it's behind a
bunch of electronics anyway, the above might be a good solution.


Best regards,
Spehro Pefhany


The series current-limiting cap dissipates no power, so it can be
shorted by a low voltage switch. If it drives, say, the input of a
bridge rectifier or a 2-diode restore thing, short the input of that.
It becomes a bang-bang regulator. If the controller is to be a custom
IC, a modest amount of complexity is free, so some intelligent
zero-crossing thing would be appropriate. But just dumb bang-bang
ought to work.


This is one variation:

https://dl.dropbox.com/u/53724080/Ci..._regulator.jpg

The first diode can be the fet's substrate diode, saving one part.

This is like an alternator regulator that shorts the alternator output
with a triac, to get regulation.

People often add a series resistor, for spike protection, and that
will dissipate some power, but no more than it would with a zener
shunt regulator.



that looks just like a charging circuit I tried once, only I didn't have
a ripple cap. All I had was a - feed back zener and a bjt with a
by pass diode, at the time. I only used a 24V AC source but the idea was
to allow it to have a constant short with out internal heating.

I wanted a pulse type of charging instead of constant DC.







10u
600V SI 30 Hz pulse out
||
-||-+--+------+----+-|-+-+---------------------+
|| | | +
AC line in | | z Max Voltage limit Diode
| | A
| | |
surge clamp z | |
A + HV NPN V Back flow stopper
-(diode too) | | -
5 watt + \| |
| |+--------+-------+
| | .-. +
| + | | ---
| | | | ---
| | '+' +
+------+-----------++------+
|
===
GND
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

Even though that works, I wouldn't suggest using AC over 48 volts
unless you have it totally enclosed.

Never thought of trying a mosfet for that, I have seen some that have
zenering substrate diodes. Those can do the job of both the required
diode and the noise pulse that may exceed the fets voltage.

If I remember there was a little (-) voltage coming back through the
collector but it didn't seem to bother the rest of it.

Jamie


That looks equivalent to a shunt zener. The NPN runs in linear mode
and gets hot.




Not really, the idea is to select the dropping cap to deliver only
what you need and the excess is shunted via the NPN. Excess being no load or
topped off battery after charge.

Your use of a mosfet in the same place being regulated in linear mode
would also do the same, it could even oscillate if the ripple wasn't
properly handled in the - feed back. I suppose one could use a buck
switcher to reduce heat if that is an issue.

The charger I made didn't generate any heat that was even noticeable and
that was with no heat sink. I don't suggest such designs due to their
nature in design, they aren't that safe..

Jamie

John Larkin wrote:

On Tue, 02 Oct 2012 17:47:20 -0400, Jamie
t wrote:


John Larkin wrote:

On Sun, 30 Sep 2012 17:21:30 -0400, Jamie
et wrote:



John Larkin wrote:



On Sat, 29 Sep 2012 19:34:02 -0400, Spehro Pefhany
wrote:




On Thu, 27 Sep 2012 12:44:00 -0700, the renowned Jim Thompson
wrote:




AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson

If it's full-wave rectified you can turn a HV part 'off' when the
voltage exceeds your desired output voltage and lose the series cap.
Your output cap need only be as big as a full-wave rectified low
voltage supply would required.

The cap is better with transients most likely, but if it's behind a
bunch of electronics anyway, the above might be a good solution.


Best regards,
Spehro Pefhany


The series current-limiting cap dissipates no power, so it can be
shorted by a low voltage switch. If it drives, say, the input of a
bridge rectifier or a 2-diode restore thing, short the input of that.
It becomes a bang-bang regulator. If the controller is to be a custom
IC, a modest amount of complexity is free, so some intelligent
zero-crossing thing would be appropriate. But just dumb bang-bang
ought to work.


This is one variation:

https://dl.dropbox.com/u/53724080/Ci..._regulator.jpg

The first diode can be the fet's substrate diode, saving one part.

This is like an alternator regulator that shorts the alternator output
with a triac, to get regulation.

People often add a series resistor, for spike protection, and that
will dissipate some power, but no more than it would with a zener
shunt regulator.



that looks just like a charging circuit I tried once, only I didn't have
a ripple cap. All I had was a - feed back zener and a bjt with a
by pass diode, at the time. I only used a 24V AC source but the idea was
to allow it to have a constant short with out internal heating.

I wanted a pulse type of charging instead of constant DC.







10u
600V SI 30 Hz pulse out
||
-||-+--+------+----+-|-+-+---------------------+
|| | | +
AC line in | | z Max Voltage limit Diode
| | A
| | |
surge clamp z | |
A + HV NPN V Back flow stopper
-(diode too) | | -
5 watt + \| |
| |+--------+-------+
| | .-. +
| + | | ---
| | | | ---
| | '+' +
+------+-----------++------+
|
===
GND
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

Even though that works, I wouldn't suggest using AC over 48 volts
unless you have it totally enclosed.

Never thought of trying a mosfet for that, I have seen some that have
zenering substrate diodes. Those can do the job of both the required
diode and the noise pulse that may exceed the fets voltage.

If I remember there was a little (-) voltage coming back through the
collector but it didn't seem to bother the rest of it.

Jamie


That looks equivalent to a shunt zener. The NPN runs in linear mode
and gets hot.





Not really, the idea is to select the dropping cap to deliver only
what you need and the excess is shunted via the NPN. Excess being no load or
topped off battery after charge.


It does the same as a single zener, but is more complex.


Your use of a mosfet in the same place being regulated in linear mode
would also do the same,


No, my circuit goes into zero dissipation mode when it doesn't need to
charge the cap. The low-voltage shunt mosfet (or NPN) could be
integrated into a controller chip. Maybe Jim can patent the idea.



Body diode?


Jamie

On Thu, 27 Sep 2012 12:44:00 -0700, Jim Thompson
wrote:

AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson

I ended up with this...

http://www.analog-innovations.com/SE...00056_MOD3.pdf

Using a depletion-mode NMOS FET.

I have a version I personally liked better that used a cheapy TRIAC
under DDROP3, but I could not find a way to get some "free" power for
the gate... needed while pumping, goes away when overcome by the
switcher coming on line.

(This is a wild high PFC, high efficiency dude, where the customer is
squeezing me for milliwatts :-)

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

On Tue, 02 Oct 2012 19:17:45 -0400, Jamie
t wrote:

John Larkin wrote:

On Tue, 02 Oct 2012 17:47:20 -0400, Jamie
t wrote:


John Larkin wrote:

On Sun, 30 Sep 2012 17:21:30 -0400, Jamie
jamie_ka1lpa_not_valid_after_ka1lpa_@charter. net wrote:



John Larkin wrote:



On Sat, 29 Sep 2012 19:34:02 -0400, Spehro Pefhany
wrote:




On Thu, 27 Sep 2012 12:44:00 -0700, the renowned Jim Thompson
wrote:




AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson

If it's full-wave rectified you can turn a HV part 'off' when the
voltage exceeds your desired output voltage and lose the series cap.
Your output cap need only be as big as a full-wave rectified low
voltage supply would required.

The cap is better with transients most likely, but if it's behind a
bunch of electronics anyway, the above might be a good solution.


Best regards,
Spehro Pefhany


The series current-limiting cap dissipates no power, so it can be
shorted by a low voltage switch. If it drives, say, the input of a
bridge rectifier or a 2-diode restore thing, short the input of that.
It becomes a bang-bang regulator. If the controller is to be a custom
IC, a modest amount of complexity is free, so some intelligent
zero-crossing thing would be appropriate. But just dumb bang-bang
ought to work.


This is one variation:

https://dl.dropbox.com/u/53724080/Ci..._regulator.jpg

The first diode can be the fet's substrate diode, saving one part.

This is like an alternator regulator that shorts the alternator output
with a triac, to get regulation.

People often add a series resistor, for spike protection, and that
will dissipate some power, but no more than it would with a zener
shunt regulator.



that looks just like a charging circuit I tried once, only I didn't have
a ripple cap. All I had was a - feed back zener and a bjt with a
by pass diode, at the time. I only used a 24V AC source but the idea was
to allow it to have a constant short with out internal heating.

I wanted a pulse type of charging instead of constant DC.







10u
600V SI 30 Hz pulse out
||
-||-+--+------+----+-|-+-+---------------------+
|| | | +
AC line in | | z Max Voltage limit Diode
| | A
| | |
surge clamp z | |
A + HV NPN V Back flow stopper
-(diode too) | | -
5 watt + \| |
| |+--------+-------+
| | .-. +
| + | | ---
| | | | ---
| | '+' +
+------+-----------++------+
|
===
GND
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

Even though that works, I wouldn't suggest using AC over 48 volts
unless you have it totally enclosed.

Never thought of trying a mosfet for that, I have seen some that have
zenering substrate diodes. Those can do the job of both the required
diode and the noise pulse that may exceed the fets voltage.

If I remember there was a little (-) voltage coming back through the
collector but it didn't seem to bother the rest of it.

Jamie


That looks equivalent to a shunt zener. The NPN runs in linear mode
and gets hot.





Not really, the idea is to select the dropping cap to deliver only
what you need and the excess is shunted via the NPN. Excess being no load or
topped off battery after charge.


It does the same as a single zener, but is more complex.


Your use of a mosfet in the same place being regulated in linear mode
would also do the same,


No, my circuit goes into zero dissipation mode when it doesn't need to
charge the cap. The low-voltage shunt mosfet (or NPN) could be
integrated into a controller chip. Maybe Jim can patent the idea.



Body diode?


Jamie

As Spehro suggested, the fet can be turned on when the current swings
negative, which shorts the body diode and improves efficiency a tiny
bit more.


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators

On Tue, 02 Oct 2012 17:50:14 -0700, Jim Thompson
wrote:

On Thu, 27 Sep 2012 12:44:00 -0700, Jim Thompson
wrote:

AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson

I ended up with this...

http://www.analog-innovations.com/SE...00056_MOD3.pdf

Using a depletion-mode NMOS FET.

I have a version I personally liked better that used a cheapy TRIAC
under DDROP3, but I could not find a way to get some "free" power for
the gate... needed while pumping, goes away when overcome by the
switcher coming on line.

(This is a wild high PFC, high efficiency dude, where the customer is
squeezing me for milliwatts :-)

...Jim Thompson

That's crazy. Not only is it expensive, once the 24 volt supply kicks
in, it dissipates most of a watt, doing nothing.

Boy, did I just save you some embarassment.


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators

On Tue, 02 Oct 2012 20:31:25 -0700, John Larkin
wrote:

On Tue, 02 Oct 2012 17:50:14 -0700, Jim Thompson
wrote:

On Thu, 27 Sep 2012 12:44:00 -0700, Jim Thompson
wrote:

AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson

I ended up with this...

http://www.analog-innovations.com/SE...00056_MOD3.pdf

Using a depletion-mode NMOS FET.

I have a version I personally liked better that used a cheapy TRIAC
under DDROP3, but I could not find a way to get some "free" power for
the gate... needed while pumping, goes away when overcome by the
switcher coming on line.

(This is a wild high PFC, high efficiency dude, where the customer is
squeezing me for milliwatts :-)

...Jim Thompson

That's crazy. Not only is it expensive, once the 24 volt supply kicks
in, it dissipates most of a watt, doing nothing.

Boy, did I just save you some embarassment.

You're so ignorant you don't know how it works. Thanks for the
exhibition!

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
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I love to cook with wine. Sometimes I even put it in the food.

On Tue, 02 Oct 2012 21:11:23 -0700, Jim Thompson
wrote:

On Tue, 02 Oct 2012 20:31:25 -0700, John Larkin
wrote:

On Tue, 02 Oct 2012 17:50:14 -0700, Jim Thompson
wrote:

On Thu, 27 Sep 2012 12:44:00 -0700, Jim Thompson
wrote:

AC Cap Dropper DC Power Supply

Anyone know of a clever way to regulate other than the typical
brute-force zener clamp?

...Jim Thompson

I ended up with this...

http://www.analog-innovations.com/SE...00056_MOD3.pdf

Using a depletion-mode NMOS FET.

I have a version I personally liked better that used a cheapy TRIAC
under DDROP3, but I could not find a way to get some "free" power for
the gate... needed while pumping, goes away when overcome by the
switcher coming on line.

(This is a wild high PFC, high efficiency dude, where the customer is
squeezing me for milliwatts :-)

...Jim Thompson

That's crazy. Not only is it expensive, once the 24 volt supply kicks
in, it dissipates most of a watt, doing nothing.

Boy, did I just save you some embarassment.

You're so ignorant you don't know how it works. Thanks for the
exhibition!

...Jim Thompson

Well, how much power do R1, R2, the TL431, and ROFF dissipate once the
main supply is up?

Harder question: what's the worst-case dissipation of the fet if the
main supply doesn't come up, like if the load is shorted or something?


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation
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