Hi All,

I recently bought and installed a Manrose timer board for one of their inline fans (so it runs on after the lights are turned off). I installed it this weekend (actually driving a similar fan from another manufacturer).

It's working fine, but I found it a little curious...€¦.

It's a tiny PCB with quite small tracks. It only has about 10-12 components, from memory, a small transistor at the input end together with a pot to adjust the delay, a big resistor, a handful of tiny things most of which are probably resistors, but one or two could be diodes or something else a chip, and another little transistor at the output end. The permenant live is just a track that goes straight to the output, and the neutral goes most of the way there and then gets switched to the output.

Thing is, in my limited experience, transistors and chips required a power supply of some sort to convert mains to 5V and or 12V DC. But I couldn't see anything on the board that I recognised as being capable of doing this.
Are there now 240V AC chips? Have there always been and I've just not come across them before?

I got it for about £10 by the way (on special offer, reduced by 50-ish %), so a nice cheap simple way to add a timer to something that doesn't require much wattage.

On 28 Sep 2020 at 10:48:04 BST, "Chris Holmes"
wrote:

Hi All,

I recently bought and installed a Manrose timer board for one of their inline
fans (so it runs on after the lights are turned off). I installed it this
weekend (actually driving a similar fan from another manufacturer).

It's working fine, but I found it a little curious...€¦.

It's a tiny PCB with quite small tracks. It only has about 10-12
components, from memory, a small transistor at the input end together with a
pot to adjust the delay, a big resistor, a handful of tiny things most of
which are probably resistors, but one or two could be diodes or something
else a chip, and another little transistor at the output end. The permenant
live is just a track that goes straight to the output, and the neutral goes
most of the way there and then gets switched to the output.

Thing is, in my limited experience, transistors and chips required a power
supply of some sort to convert mains to 5V and or 12V DC. But I couldn't see
anything on the board that I recognised as being capable of doing this.
Are there now 240V AC chips? Have there always been and I've just not come
across them before?

I got it for about £10 by the way (on special offer, reduced by 50-ish %), so
a nice cheap simple way to add a timer to something that doesn't require much
wattage.

I think the secret is low current consumption. To drop (most of) 240V at,
say, 5mA needs only to dissipate 240 x 5 x 10^-3, that is about 1.2W and the
large resistor can probably do that even air cooled. Only few low power
components are needed to voltage limit, smooth and regulate the low voltage
supply. There should be an electrolytic capacitor though, unless anyone can
give a clue how to avoid it.

--
Roger Hayter

On 28 Sep 2020 10:04:56 GMT, Roger Hayter wrote:

I think the secret is low current consumption. To drop (most of) 240V
at, say, 5mA needs only to dissipate 240 x 5 x 10^-3, that is about 1.2W
and the large resistor can probably do that even air cooled.

Agreed but I think "capacitive droppers" are more effcient.

Only few low power components are needed to voltage limit, smooth and
regulate the low voltage supply.

Good regulation probably isn't needed as the load will be known and
thus the voltage determined with component values.

There should be an electrolytic capacitor though, unless anyone can
give a clue how to avoid it.

A capacitive dropper uses a non-polarised capacitor IIRC but normally
a wire ended device rather than surface mount.
--
Cheers
Dave.

On 28/09/2020 10:48, Chris Holmes wrote:
Hi All,

I recently bought and installed a Manrose timer board for one of
their inline fans (so it runs on after the lights are turned off). I
installed it this weekend (actually driving a similar fan from
another manufacturer).

It's working fine, but I found it a little curious...€¦.

It's a tiny PCB with quite small tracks. It only has about 10-12
components, from memory, a small transistor at the input end together
with a pot to adjust the delay, a big resistor, a handful of tiny
things most of which are probably resistors, but one or two could be
diodes or something else a chip, and another little transistor at the
output end. The permenant live is just a track that goes straight to
the output, and the neutral goes most of the way there and then gets
switched to the output.

Thing is, in my limited experience, transistors and chips required a
power supply of some sort to convert mains to 5V and or 12V DC. But
I couldn't see anything on the board that I recognised as being
capable of doing this. Are there now 240V AC chips? Have there
always been and I've just not come across them before?

Chances are that as a circuit that doesn't have to be exposed to people
they use a capacitive divider and a diode to generate the small amount
of DC power that the timer circuit needs to operate and that the thing
doing the switching is a power thyristor or triac.

Those have been available at mains voltages almost forever.

--
Regards,
Martin Brown

On 28/09/2020 10:48:04, Chris Holmes wrote:
Hi All,

I recently bought and installed a Manrose timer board for one of
their inline fans (so it runs on after the lights are turned off). I
installed it this weekend (actually driving a similar fan from
another manufacturer).

It's working fine, but I found it a little curious...€¦.

It's a tiny PCB with quite small tracks. It only has about 10-12
components, from memory, a small transistor at the input end together
with a pot to adjust the delay, a big resistor, a handful of tiny
things most of which are probably resistors, but one or two could be
diodes or something else a chip, and another little transistor at the
output end. The permenant live is just a track that goes straight to
the output, and the neutral goes most of the way there and then gets
switched to the output.

The small transistor is likely to be a Thyrister or SCR.

There are chips that can regulate from 240V to 5V using the first part
of the AC waveform though never used one. Mains voltage capable chips
are available but not common place.

Thing is, in my limited experience, transistors and chips required a
power supply of some sort to convert mains to 5V and or 12V DC. But
I couldn't see anything on the board that I recognised as being
capable of doing this. Are there now 240V AC chips? Have there
always been and I've just not come across them before?

A resistor, diode and zener can get you a low power 5V.

I got it for about £10 by the way (on special offer, reduced by
50-ish %), so a nice cheap simple way to add a timer to something
that doesn't require much wattage.

Chris Holmes wrote:
Hi All,

I recently bought and installed a Manrose timer board for one of their inline fans (so it runs on after the lights are turned off). I installed it this weekend (actually driving a similar fan from another manufacturer).

It's working fine, but I found it a little curious...€¦.

It's a tiny PCB with quite small tracks. It only has about 10-12 components, from memory, a small transistor at the input end together with a pot to adjust the delay, a big resistor, a handful of tiny things most of which are probably resistors, but one or two could be diodes or something else a chip, and another little transistor at the output end. The permenant live is just a track that goes straight to the output, and the neutral goes most of the way there and then gets switched to the output.

Thing is, in my limited experience, transistors and chips required a power supply of some sort to convert mains to 5V and or 12V DC. But I couldn't see anything on the board that I recognised as being capable of doing this.
Are there now 240V AC chips? Have there always been and I've just not come across them before?

I got it for about £10 by the way (on special offer, reduced by 50-ish %), so a nice cheap simple way to add a timer to something that doesn't require much wattage.

Plugged "Manrose timer board" into Google and got an iFixit link
with a Youtube reference.

"How to Fix an Extractor Fan Timer"

https://youtu.be/UxU-ZQp2ag4

CD4001BE, big-ass RC (analog) timer circuit ?
Like making an amplifier out of CMOS logic.

Have a look and see if it's similar to yours.

There is a large resistor that does the dropping
to bring the 240V down to some lower level. Notice
in the video that his resistor is cracked or has some
surface damage of some sort. Looks safe and reliable.

A non-isolated circuit ? What's not to like ?

I was hoping for a schematic, but that's too much
to expect.

Paul

On Monday, September 28, 2020 at 11:05:01 AM UTC+1, Roger Hayter wrote:
Snip

I think the secret is low current consumption. To drop (most of) 240V at,
say, 5mA needs only to dissipate 240 x 5 x 10^-3, that is about 1.2W and the
large resistor can probably do that even air cooled. Only few low power
components are needed to voltage limit, smooth and regulate the low voltage
supply. There should be an electrolytic capacitor though, unless anyone can
give a clue how to avoid it.

--
Roger Hayter

You are quite right Roger, I had forgotten there was a couple of small electrolytics near the input).

And thanks everyone, I shall probably never build anything like this, but it's interesting to know how they have powered what I presume is low voltage stuff.

On 28/09/2020 10:48, Chris Holmes wrote:
Hi All,

I recently bought and installed a Manrose timer board for one of
their inline fans (so it runs on after the lights are turned off). I
installed it this weekend (actually driving a similar fan from
another manufacturer).

It's working fine, but I found it a little curious...€¦.

It's a tiny PCB with quite small tracks. It only has about 10-12
components, from memory, a small transistor at the input end together
with a pot to adjust the delay, a big resistor, a handful of tiny
things most of which are probably resistors, but one or two could be
diodes or something else a chip, and another little transistor at the
output end. The permenant live is just a track that goes straight to
the output, and the neutral goes most of the way there and then gets
switched to the output.

Thing is, in my limited experience, transistors and chips required a
power supply of some sort to convert mains to 5V and or 12V DC. But
I couldn't see anything on the board that I recognised as being
capable of doing this. Are there now 240V AC chips? Have there
always been and I've just not come across them before?

1/. Yes there are. But probably you only have one on the board. To
switch the mains.
2/. As far as the rest of the circuit is concerned the easiest way to
drop voltage if the current draw is constant is via a mains rated
capacitor. Then rectify and smooth the output enough.
3/ a more expensive way is to have a high frequency mains transistor
chop the mains and feed that through a tiny transformer, but it sounds
like that is more complex than your circuit's designer wanted to pay for..

I got it for about £10 by the way (on special offer, reduced by
50-ish %), so a nice cheap simple way to add a timer to something
that doesn't require much wattage.

Digital crap is so cheap that it probably uses some sort of timer, and
doesn't therefore need any greatly smoothed power supply.

--
The lifetime of any political organisation is about three years before
its been subverted by the people it tried to warn you about.

Anon.

On 28/09/2020 11:04, Roger Hayter wrote:
I think the secret is low current consumption. To drop (most of) 240V at,
say, 5mA needs only to dissipate 240 x 5 x 10^-3, that is about 1.2W and the
large resistor can probably do that even air cooled.

don't even need that. A capacitor of as it happens about 0.63µF will
deliver 5mA into a small circuit and be more reliable cooler and cheaper.
Feed that into a diode bridge and, if my back of envelope is right, 50µF
and you will have less than 1V of ripple at 5mA.



Only few low power
components are needed to voltage limit, smooth and regulate the low voltage
supply. There should be an electrolytic capacitor though, unless anyone can
give a clue how to avoid it.

well yes, and that's by going v high frequency, but then you need a
choke or transformer instead...


--
Climate Change: Socialism wearing a lab coat.

In article ,
Chris Holmes wrote:
Thing is, in my limited experience, transistors and chips required a
power supply of some sort to convert mains to 5V and or 12V DC. But I
couldn't see anything on the board that I recognised as being capable of
doing this.

Think dimmers. Which have been around for a long long time. Without a low
volts transformer. And some later ones have quite sophisticated
electronics as well as a triac or whatever.

--
*Laugh alone and the world thinks you're an idiot.

Dave Plowman London SW
To e-mail, change noise into sound.

On 28/09/2020 12:11, Fredxx wrote:

A resistor, diode and zener can get you a low power 5V.

Not low power - you are dropping around 230V through that resistor. Even
at only 5mA that is 1.65W to be dissipated, and that is considerably
more than a standard resistor will handle . Interestingly, Paul's post
notes "There is a large resistor that does the dropping to bring the
240V down to some lower level."

--

Jeff

Chris Holmes was thinking very hard :
Thing is, in my limited experience, transistors and chips required a power
supply of some sort to convert mains to 5V and or 12V DC. But I couldn't see
anything on the board that I recognised as being capable of doing this.
Are there now 240V AC chips? Have there always been and I've just not come
across them before?

It will use a triac for switching and likely a mains rated capacitor
and diode as a capacitive dropper, to reduce the mains voltage down to
a useable AC voltage.

On 28 Sep 2020 at 11:49:53 BST, ""Dave Liquorice""
wrote:

On 28 Sep 2020 10:04:56 GMT, Roger Hayter wrote:

I think the secret is low current consumption. To drop (most of) 240V
at, say, 5mA needs only to dissipate 240 x 5 x 10^-3, that is about 1.2W
and the large resistor can probably do that even air cooled.

Agreed but I think "capacitive droppers" are more effcient.

Maybe so, but I took the OP's description of the module to exclude the
presence of a mains-rated capacitor.



Only few low power components are needed to voltage limit, smooth and
regulate the low voltage supply.

Good regulation probably isn't needed as the load will be known and
thus the voltage determined with component values.

There should be an electrolytic capacitor though, unless anyone can
give a clue how to avoid it.

A capacitive dropper uses a non-polarised capacitor IIRC but normally
a wire ended device rather than surface mount.


--
Roger Hayter

On 28/09/2020 14:48:07, Jeff Layman wrote:
On 28/09/2020 12:11, Fredxx wrote:

A resistor, diode and zener can get you a low power 5V.

Not low power - you are dropping around 230V through that resistor. Even
at only 5mA that is 1.65W to be dissipated, and that is considerably
more than a standard resistor will handle .

It would be less than 1.2W but I take your point. There could also be a
series cap to drop some of the volts.

Hardly an ornate solution but cheap.

Interestingly, Paul's post
notes "There is a large resistor that does the dropping to bring the
240V down to some lower level."

Interestingly, Paul's post
notes "There is a large resistor that does the dropping to bring the
240V down to some lower level."

I have replaced (removed) a couple of these boards over the years. They had failed, and the big resistor was quite charred in both cases!

On Mon, 28 Sep 2020 07:14:34 -0400, Paul
wrote:


Chris Holmes wrote:

Hi All,

I recently bought and installed a Manrose timer board for one of their inline fans (so it runs on after the lights are turned off). I installed it this weekend (actually driving a similar fan from another manufacturer).

It's working fine, but I found it a little curious...….

It's a tiny PCB with quite small tracks. It only has about 10-12 components, from memory, a small transistor at the input end together with a pot to adjust the delay, a big resistor, a handful of tiny things most of which are probably resistors, but one or two could be diodes or something else a chip, and another little transistor at the output end. The permenant live is just a track that goes straight to the output, and the neutral goes most of the way there and then gets switched to the output.

Thing is, in my limited experience, transistors and chips required a power supply of some sort to convert mains to 5V and or 12V DC. But I couldn't see anything on the board that I recognised as being capable of doing this.
Are there now 240V AC chips? Have there always been and I've just not come across them before?

I got it for about £10 by the way (on special offer, reduced by 50-ish %), so a nice cheap simple way to add a timer to something that doesn't require much wattage.


Plugged "Manrose timer board" into Google and got an iFixit link
with a Youtube reference.

"How to Fix an Extractor Fan Timer"

https://youtu.be/UxU-ZQp2ag4

CD4001BE, big-ass RC (analog) timer circuit ?
Like making an amplifier out of CMOS logic.

Have a look and see if it's similar to yours.

There is a large resistor that does the dropping
to bring the 240V down to some lower level. Notice
in the video that his resistor is cracked or has some
surface damage of some sort. Looks safe and reliable.

A non-isolated circuit ? What's not to like ?

I was hoping for a schematic, but that's too much
to expect.

Paul


I followed your tracks and found a better video. The PCB in yours was
marked 1998, but the one in mine is 2008, and has a big copper PCB
land on one leg of the big resistor in an attempt to add more cooling.

(The presenter sounds like an aircraft pilot welcoming passengers).

I've worked out the circuit and added an explanation. See:
https://www.dropbox.com/s/hmxsxtxt0x...Timer.jpg?dl=0

I am guessing that the IC runs on 12V and the trimmer is 2M to give a
delay of 1 to 20 minutes.
--
Dave W

On 30/09/2020 09:22, David wrote:
Interestingly, Paul's post
notes "There is a large resistor that does the dropping to bring the
240V down to some lower level."

I have replaced (removed) a couple of these boards over the years. They had failed, and the big resistor was quite charred in both cases!


https://youtu.be/UxU-ZQp2ag4

--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

Dave W wrote:
On Mon, 28 Sep 2020 07:14:34 -0400, Paul
wrote:

Chris Holmes wrote:
Hi All,

I recently bought and installed a Manrose timer board for one of their inline fans (so it runs on after the lights are turned off). I installed it this weekend (actually driving a similar fan from another manufacturer).

It's working fine, but I found it a little curious...….

It's a tiny PCB with quite small tracks. It only has about 10-12 components, from memory, a small transistor at the input end together with a pot to adjust the delay, a big resistor, a handful of tiny things most of which are probably resistors, but one or two could be diodes or something else a chip, and another little transistor at the output end. The permenant live is just a track that goes straight to the output, and the neutral goes most of the way there and then gets switched to the output.

Thing is, in my limited experience, transistors and chips required a power supply of some sort to convert mains to 5V and or 12V DC. But I couldn't see anything on the board that I recognised as being capable of doing this.
Are there now 240V AC chips? Have there always been and I've just not come across them before?

I got it for about £10 by the way (on special offer, reduced by 50-ish %), so a nice cheap simple way to add a timer to something that doesn't require much wattage.
Plugged "Manrose timer board" into Google and got an iFixit link
with a Youtube reference.

"How to Fix an Extractor Fan Timer"

https://youtu.be/UxU-ZQp2ag4

CD4001BE, big-ass RC (analog) timer circuit ?
Like making an amplifier out of CMOS logic.

Have a look and see if it's similar to yours.

There is a large resistor that does the dropping
to bring the 240V down to some lower level. Notice
in the video that his resistor is cracked or has some
surface damage of some sort. Looks safe and reliable.

A non-isolated circuit ? What's not to like ?

I was hoping for a schematic, but that's too much
to expect.

Paul

I followed your tracks and found a better video. The PCB in yours was
marked 1998, but the one in mine is 2008, and has a big copper PCB
land on one leg of the big resistor in an attempt to add more cooling.

(The presenter sounds like an aircraft pilot welcoming passengers).

I've worked out the circuit and added an explanation. See:
https://www.dropbox.com/s/hmxsxtxt0x...Timer.jpg?dl=0

I am guessing that the IC runs on 12V and the trimmer is 2M to give a
delay of 1 to 20 minutes.

Neat. That looks about right. Fast attack, slow decay circuit.
The diode in the upper left could be a 1N4007. For the price,
probably not that much more for a higher rating. I think they're
the same diode, just some are tested to higher voltages.

Does this mean the triac only conducts on half-cycles ???

The only hobby triac circuits I've had here, they were
fired by a diac.

Paul

On Sun, 04 Oct 2020 22:42:45 -0400, Paul
wrote:


Dave W wrote:

On Mon, 28 Sep 2020 07:14:34 -0400, Paul
wrote:


Chris Holmes wrote:
Hi All,

I recently bought and installed a Manrose timer board for one of their inline fans (so it runs on after the lights are turned off). I installed it this weekend (actually driving a similar fan from another manufacturer).

It's working fine, but I found it a little curious...….

It's a tiny PCB with quite small tracks. It only has about 10-12 components, from memory, a small transistor at the input end together with a pot to adjust the delay, a big resistor, a handful of tiny things most of which are probably resistors, but one or two could be diodes or something else a chip, and another little transistor at the output end. The permenant live is just a track that goes straight to the output, and the neutral goes most of the way there and then gets switched to the output.

Thing is, in my limited experience, transistors and chips required a power supply of some sort to convert mains to 5V and or 12V DC. But I couldn't see anything on the board that I recognised as being capable of doing this.
Are there now 240V AC chips? Have there always been and I've just not come across them before?

I got it for about £10 by the way (on special offer, reduced by 50-ish %), so a nice cheap simple way to add a timer to something that doesn't require much wattage.
Plugged "Manrose timer board" into Google and got an iFixit link
with a Youtube reference.

"How to Fix an Extractor Fan Timer"

https://youtu.be/UxU-ZQp2ag4

CD4001BE, big-ass RC (analog) timer circuit ?
Like making an amplifier out of CMOS logic.

Have a look and see if it's similar to yours.

There is a large resistor that does the dropping
to bring the 240V down to some lower level. Notice
in the video that his resistor is cracked or has some
surface damage of some sort. Looks safe and reliable.

A non-isolated circuit ? What's not to like ?

I was hoping for a schematic, but that's too much
to expect.

Paul


I followed your tracks and found a better video. The PCB in yours was
marked 1998, but the one in mine is 2008, and has a big copper PCB
land on one leg of the big resistor in an attempt to add more cooling.

(The presenter sounds like an aircraft pilot welcoming passengers).

I've worked out the circuit and added an explanation. See:
https://www.dropbox.com/s/hmxsxtxt0x...Timer.jpg?dl=0

I am guessing that the IC runs on 12V and the trimmer is 2M to give a
delay of 1 to 20 minutes.


Neat. That looks about right. Fast attack, slow decay circuit.
The diode in the upper left could be a 1N4007. For the price,
probably not that much more for a higher rating. I think they're
the same diode, just some are tested to higher voltages.

Does this mean the triac only conducts on half-cycles ???

The only hobby triac circuits I've had here, they were
fired by a diac.

Paul

I forgot to include a link to the video that I used for source
material:
https://youtu.be/3sumou4ScDM

Triacs conduct in both directions when the gate is held +ve, so give
full-cycle operation.

I don't know what type of 1Nxxxx diode was used - I originally put
1N4007, but changed it to 1N4004 assuming the board is made to minimal
cost. I was puzzled by the component numberings, but concluded that
they refer to the bins that the manual assemblers get the components
from, so two diodes have the same number.
--
Dave W

In article , Dave W
wrote:
On Sun, 04 Oct 2020 22:42:45 -0400, Paul wrote:

Dave W wrote:
On Mon, 28 Sep 2020 07:14:34 -0400, Paul wrote:

Chris Holmes wrote:
Hi All,

I recently bought and installed a Manrose timer board for one of
their inline fans (so it runs on after the lights are turned off).
I installed it this weekend (actually driving a similar fan from
another manufacturer).

It's working fine, but I found it a little curious...….

It's a tiny PCB with quite small tracks. It only has about 10-12
components, from memory, a small transistor at the input end
together with a pot to adjust the delay, a big resistor, a handful
of tiny things most of which are probably resistors, but one or two
could be diodes or something else a chip, and another little
transistor at the output end. The permenant live is just a track
that goes straight to the output, and the neutral goes most of the
way there and then gets switched to the output.

Thing is, in my limited experience, transistors and chips required a
power supply of some sort to convert mains to 5V and or 12V DC. But
I couldn't see anything on the board that I recognised as being
capable of doing this. Are there now 240V AC chips? Have there
always been and I've just not come across them before?

I got it for about £10 by the way (on special offer, reduced by
50-ish %), so a nice cheap simple way to add a timer to something
that doesn't require much wattage.
Plugged "Manrose timer board" into Google and got an iFixit link with
a Youtube reference.

"How to Fix an Extractor Fan Timer"

https://youtu.be/UxU-ZQp2ag4

CD4001BE, big-ass RC (analog) timer circuit ? Like making an
amplifier out of CMOS logic.

Have a look and see if it's similar to yours.

There is a large resistor that does the dropping to bring the 240V
down to some lower level. Notice in the video that his resistor is
cracked or has some surface damage of some sort. Looks safe and
reliable.

A non-isolated circuit ? What's not to like ?

I was hoping for a schematic, but that's too much to expect.

Paul

I followed your tracks and found a better video. The PCB in yours was
marked 1998, but the one in mine is 2008, and has a big copper PCB
land on one leg of the big resistor in an attempt to add more cooling.

(The presenter sounds like an aircraft pilot welcoming passengers).

I've worked out the circuit and added an explanation. See:
https://www.dropbox.com/s/hmxsxtxt0x...Timer.jpg?dl=0

I am guessing that the IC runs on 12V and the trimmer is 2M to give a
delay of 1 to 20 minutes.

Neat. That looks about right. Fast attack, slow decay circuit. The diode
in the upper left could be a 1N4007. For the price, probably not that
much more for a higher rating. I think they're the same diode, just some
are tested to higher voltages.

Does this mean the triac only conducts on half-cycles ???

The only hobby triac circuits I've had here, they were fired by a diac.

Paul
I forgot to include a link to the video that I used for source material:
https://youtu.be/3sumou4ScDM

Triacs conduct in both directions when the gate is held +ve, so give
full-cycle operation.

er, no. Triacs are diodes. To get full cycle conduction you need a pair of
triacs.

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

On Monday, 5 October 2020 10:02:15 UTC+1, charles wrote:
In article , Dave W
wrote:

Triacs conduct in both directions when the gate is held +ve, so give
full-cycle operation.

er, no. Triacs are diodes. To get full cycle conduction you need a pair of
triacs.

Yes, triacs do conduct in both directions and can be triggered with
either polarity as well. In other words, all combinations of positive
and negative voltage on the main terminals and trigger terminal are
able to trigger conduction using a single triac. The sensitivity can
however vary depending on the particular combination.

John

On 05/10/2020 11:12, wrote:
On Monday, 5 October 2020 10:02:15 UTC+1, charles wrote:
In article , Dave W
wrote:

Triacs conduct in both directions when the gate is held +ve, so give
full-cycle operation.

er, no. Triacs are diodes. To get full cycle conduction you need a pair of
triacs.

Yes, triacs do conduct in both directions and can be triggered with
either polarity as well. In other words, all combinations of positive
and negative voltage on the main terminals and trigger terminal are
able to trigger conduction using a single triac. The sensitivity can
however vary depending on the particular combination.

John

Yes, The silicon controlled rectifier is the unidirectional one: Triacs
are almost a pair in parrallel.

--
"A point of view can be a dangerous luxury when substituted for insight
and understanding".

Marshall McLuhan

The Natural Philosopher wrote:
On 05/10/2020 11:12, wrote:
On Monday, 5 October 2020 10:02:15 UTC+1, charles wrote:
In article , Dave W
wrote:

Triacs conduct in both directions when the gate is held +ve, so give
full-cycle operation.

er, no. Triacs are diodes. To get full cycle conduction you need a pair of
triacs.

Yes, triacs do conduct in both directions and can be triggered with
either polarity as well. In other words, all combinations of positive
and negative voltage on the main terminals and trigger terminal are
able to trigger conduction using a single triac. The sensitivity can
however vary depending on the particular combination.

John

Yes, The silicon controlled rectifier is the unidirectional one: Triacs
are almost a pair in parrallel.


Lots of interesting and educational stuff.

Id not have thought of building a timer out of capacitance decay.

I had a look at the YouTube video, and read the comments and someone there
had also traced the circuit and (I think) explained it.

Having heard how hot that resistor can get, Im glad mine is mounted in a
relatively large enclosure.

Perhaps I should add some ventilation!

--
Chris

On 05/10/2020 09:55:25, charles wrote:
In article , Dave W
wrote:
On Sun, 04 Oct 2020 22:42:45 -0400, Paul wrote:

Dave W wrote:
On Mon, 28 Sep 2020 07:14:34 -0400, Paul wrote:

Chris Holmes wrote:
Hi All,

I recently bought and installed a Manrose timer board for one of
their inline fans (so it runs on after the lights are turned off).
I installed it this weekend (actually driving a similar fan from
another manufacturer).

It's working fine, but I found it a little curious...€¦.

It's a tiny PCB with quite small tracks. It only has about 10-12
components, from memory, a small transistor at the input end
together with a pot to adjust the delay, a big resistor, a handful
of tiny things most of which are probably resistors, but one or two
could be diodes or something else a chip, and another little
transistor at the output end. The permenant live is just a track
that goes straight to the output, and the neutral goes most of the
way there and then gets switched to the output.

Thing is, in my limited experience, transistors and chips required a
power supply of some sort to convert mains to 5V and or 12V DC. But
I couldn't see anything on the board that I recognised as being
capable of doing this. Are there now 240V AC chips? Have there
always been and I've just not come across them before?

I got it for about £10 by the way (on special offer, reduced by
50-ish %), so a nice cheap simple way to add a timer to something
that doesn't require much wattage.
Plugged "Manrose timer board" into Google and got an iFixit link with
a Youtube reference.

"How to Fix an Extractor Fan Timer"

https://youtu.be/UxU-ZQp2ag4

CD4001BE, big-ass RC (analog) timer circuit ? Like making an
amplifier out of CMOS logic.

Have a look and see if it's similar to yours.

There is a large resistor that does the dropping to bring the 240V
down to some lower level. Notice in the video that his resistor is
cracked or has some surface damage of some sort. Looks safe and
reliable.

A non-isolated circuit ? What's not to like ?

I was hoping for a schematic, but that's too much to expect.

Paul

I followed your tracks and found a better video. The PCB in yours was
marked 1998, but the one in mine is 2008, and has a big copper PCB
land on one leg of the big resistor in an attempt to add more cooling.

(The presenter sounds like an aircraft pilot welcoming passengers).

I've worked out the circuit and added an explanation. See:
https://www.dropbox.com/s/hmxsxtxt0x...Timer.jpg?dl=0

I am guessing that the IC runs on 12V and the trimmer is 2M to give a
delay of 1 to 20 minutes.

Neat. That looks about right. Fast attack, slow decay circuit. The diode
in the upper left could be a 1N4007. For the price, probably not that
much more for a higher rating. I think they're the same diode, just some
are tested to higher voltages.

Does this mean the triac only conducts on half-cycles ???

The only hobby triac circuits I've had here, they were fired by a diac.

Paul
I forgot to include a link to the video that I used for source material:
https://youtu.be/3sumou4ScDM

Triacs conduct in both directions when the gate is held +ve, so give
full-cycle operation.

er, no. Triacs are diodes. To get full cycle conduction you need a pair of
triacs.

They are more complicated than a "diode".

FYI

A Thyristor conducts in one direction
https://en.wikipedia.org/wiki/Thyristor

A Triac can conduct on both negative and positive going part of the cycle.
https://en.wikipedia.org/wiki/TRIAC

Triacs can be turned on by passing a current in the gate. If the gate
drive has been removed they stay on until the end of the cycle when
current is lower than the holding current.

Fredxx wrote:
On 05/10/2020 09:55:25, charles wrote:
In article , Dave W
wrote:
On Sun, 04 Oct 2020 22:42:45 -0400, Paul wrote:

Dave W wrote:
On Mon, 28 Sep 2020 07:14:34 -0400, Paul
wrote:

Chris Holmes wrote:
Hi All,

I recently bought and installed a Manrose timer board for one of
their inline fans (so it runs on after the lights are turned off).
I installed it this weekend (actually driving a similar fan from
another manufacturer).

It's working fine, but I found it a little curious...€¦.

It's a tiny PCB with quite small tracks. It only has about 10-12
components, from memory, a small transistor at the input end
together with a pot to adjust the delay, a big resistor, a handful
of tiny things most of which are probably resistors, but one or two
could be diodes or something else a chip, and another little
transistor at the output end. The permenant live is just a track
that goes straight to the output, and the neutral goes most of the
way there and then gets switched to the output.

Thing is, in my limited experience, transistors and chips required a
power supply of some sort to convert mains to 5V and or 12V DC. But
I couldn't see anything on the board that I recognised as being
capable of doing this. Are there now 240V AC chips? Have there
always been and I've just not come across them before?

I got it for about £10 by the way (on special offer, reduced by
50-ish %), so a nice cheap simple way to add a timer to something
that doesn't require much wattage.
Plugged "Manrose timer board" into Google and got an iFixit link with
a Youtube reference.

"How to Fix an Extractor Fan Timer"

https://youtu.be/UxU-ZQp2ag4

CD4001BE, big-ass RC (analog) timer circuit ? Like making an
amplifier out of CMOS logic.

Have a look and see if it's similar to yours.

There is a large resistor that does the dropping to bring the 240V
down to some lower level. Notice in the video that his resistor is
cracked or has some surface damage of some sort. Looks safe and
reliable.

A non-isolated circuit ? What's not to like ?

I was hoping for a schematic, but that's too much to expect.

Paul

I followed your tracks and found a better video. The PCB in yours was
marked 1998, but the one in mine is 2008, and has a big copper PCB
land on one leg of the big resistor in an attempt to add more cooling.

(The presenter sounds like an aircraft pilot welcoming passengers).

I've worked out the circuit and added an explanation. See:
https://www.dropbox.com/s/hmxsxtxt0x...Timer.jpg?dl=0

I am guessing that the IC runs on 12V and the trimmer is 2M to give a
delay of 1 to 20 minutes.

Neat. That looks about right. Fast attack, slow decay circuit. The
diode
in the upper left could be a 1N4007. For the price, probably not that
much more for a higher rating. I think they're the same diode, just
some
are tested to higher voltages.

Does this mean the triac only conducts on half-cycles ???

The only hobby triac circuits I've had here, they were fired by a diac.

Paul
I forgot to include a link to the video that I used for source material:
https://youtu.be/3sumou4ScDM

Triacs conduct in both directions when the gate is held +ve, so give
full-cycle operation.

er, no. Triacs are diodes. To get full cycle conduction you need a
pair of
triacs.

They are more complicated than a "diode".

FYI

A Thyristor conducts in one direction
https://en.wikipedia.org/wiki/Thyristor

A Triac can conduct on both negative and positive going part of the cycle.
https://en.wikipedia.org/wiki/TRIAC

Triacs can be turned on by passing a current in the gate. If the gate
drive has been removed they stay on until the end of the cycle when
current is lower than the holding current.

That's why triacs are sometimes fed by diacs.

https://en.wikipedia.org/wiki/DIAC

So you have control of the triac gate during
both half-cycles.

The one I built-up at home forty years ago, used a diac.

Paul

On Wed, 30 Sep 2020 01:22:30 -0700 (PDT), David
wrote:


Interestingly, Paul's post
notes "There is a large resistor that does the dropping to bring the
240V down to some lower level."


I have replaced (removed) a couple of these boards over the years. They had failed, and the big resistor was quite charred in both cases!


In the later of the two videos quoted, the big resistor looks like
11K, which works out at 2.6W at 240V half-wave rectified. This is fine
in a 3W resistor in free air, but the trouble is that it isn't.

The triac in the 2nd video needs 5mA max to trigger, so probably the
big resistor could be increased to 22K. In fact the man in the first
video with unknown triac says it's 22K and that his meter agrees. The
colours look more brown than red but maybe it's because they're burnt.

If only 5mA is needed, a 0.1uF X-rated capacitor could be used
instead, but this would cost more like 50p.
--
Dave W