A little homemade 1920s 1 valve set with direct heated triode (unmarked). I've traced most of the circuit, looks very simple. Not tried to trace the main coil assembly with its 6 connections yet. The valve has a grid leak resistor for -ve bias without C battery. It runs high R phones, no speaker. 1st question is what sort of HT voltage and/or anode current should I aim for?


NT

On Mon, 26 Aug 2019 19:22:35 -0700 (PDT), wrote:

A little homemade 1920s 1 valve set with direct heated triode (unmarked). I've traced most of the circuit, looks very simple. Not tried to trace the main coil assembly with its 6 connections yet. The valve has a grid leak resistor for -ve bias without C battery. It runs high R phones, no speaker. 1st question is what sort of HT voltage and/or anode current should I aim for?


NT

One triode from that era is the A415. The datasheet lists Va between 20 and
150V, saturation current of 30 mA and default anode current of 3 mA.

On 2019/08/26 8:24 p.m., Arid ace wrote:
On Mon, 26 Aug 2019 19:22:35 -0700 (PDT), wrote:

A little homemade 1920s 1 valve set with direct heated triode (unmarked). I've traced most of the circuit, looks very simple. Not tried to trace the main coil assembly with its 6 connections yet. The valve has a grid leak resistor for -ve bias without C battery. It runs high R phones, no speaker. 1st question is what sort of HT voltage and/or anode current should I aim for?


NT

One triode from that era is the A415. The datasheet lists Va between 20 and
150V, saturation current of 30 mA and default anode current of 3 mA.


Indeed, you need to know the tube value to be sure, but consider the
cost of batteries of the day and thus the B+ is likely 45VDC or thereabouts.

In those days some people made their own B+ batteries - way back when I
was a kid digging through attics in Toronto (mid 1960s) for old battery
sets I found a couple of home-made lead acid batteries that were glass
test tubes about 8 inches long mounted in a wooden box and there must
have been 15 to 20 in each case. Wish I still had them as they were
classic home-brew stuff which I always loved from the battery age of radio.

John :-#)#

--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
(604)872-5757 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

John Robertson wrote:


Indeed, you need to know the tube value to be sure, but consider the
cost of batteries of the day and thus the B+ is likely 45VDC or thereabouts.

In those days some people made their own B+ batteries - way back when I
was a kid digging through attics in Toronto (mid 1960s) for old battery
sets I found a couple of home-made lead acid batteries that were glass
test tubes about 8 inches long mounted in a wooden box and there must
have been 15 to 20 in each case. Wish I still had them as they were
classic home-brew stuff which I always loved from the battery age of radio.



** The "battery age of (tube) radio" extended well into the 1960s.

Popular "portables" of that era used a pair of 45V packs for B+ and a large 1.5V dry cell for tube heaters - all made by "Eveready".

Miniature 7 pin tubes like the 1S4 and 1R5 were used - along with a transformer supply for home use with a multi-finned selenium rectifier.

https://www.radiomuseum.org/tubes/tube_1s4.html



...... Phil

On 8/27/19 2:44 AM, Phil Allison wrote:


** The "battery age of (tube) radio" extended well into the 1960s.

Popular "portables" of that era used a pair of 45V packs for B+ and a large 1.5V dry cell for tube heaters - all made by "Eveready".

Miniature 7 pin tubes like the 1S4 and 1R5 were used - along with a transformer supply for home use with a multi-finned selenium rectifier.

https://www.radiomuseum.org/tubes/tube_1s4.html



..... Phil


Hello, and I once owned a Red case 4-tube (1R5, 1U4, 1U5, 3Q4)
Westinghouse H-496P4 AM-band portable that used a 67.5 volt B-battery.
The radio had a large speaker and sounded real nice but that B-batt was
expensive. Sincerely,

--
J. B. Wood e-mail:

On 27/08/19 07:44, Phil Allison wrote:
John Robertson wrote:


Indeed, you need to know the tube value to be sure, but consider the
cost of batteries of the day and thus the B+ is likely 45VDC or thereabouts.

In those days some people made their own B+ batteries - way back when I
was a kid digging through attics in Toronto (mid 1960s) for old battery
sets I found a couple of home-made lead acid batteries that were glass
test tubes about 8 inches long mounted in a wooden box and there must
have been 15 to 20 in each case. Wish I still had them as they were
classic home-brew stuff which I always loved from the battery age of radio.



** The "battery age of (tube) radio" extended well into the 1960s.

Popular "portables" of that era used a pair of 45V packs for B+ and a large 1.5V dry cell for tube heaters - all made by "Eveready".

Miniature 7 pin tubes like the 1S4 and 1R5 were used - along with a transformer supply for home use with a multi-finned selenium rectifier.

https://www.radiomuseum.org/tubes/tube_1s4.html

I've still got one of these, bought by my father in 1955:
https://www.radiomuseum.org/r/pye_p131mbq.html

It still works on mains (I doubt it would be possible to find a decent
B126 90v battery today); I added a miniature earphone socket in the
early 60s. What amazes me is that this cost £13 new at the time - the
equivalent of around £345 today!

--

Jeff

That will, very likely, be an Armstrong-circuit regenerative radio based on a common tube of the day, and what comes immediately to mind is the O1A, a 4-pin triode and good performer.

Filament voltage is 5 VDC - polarity not critical.
B+ will be 90 - 135 VDC
Grid voltage will be -4.5 - -9 VDC

http://www.bunkerofdoom.com/tubes/sy...A/1943/P20.GIF

Overall, those early triodes were not very efficient as compared to "modern" miniatures of the late 1940s and 1950s.

Note that this basic design often included a variety of plug-in coils for conventional broadcast, SW and other bands as may have been available at the time. Keep in mind that 'official' regulation of land-based broadcast radio did not start (have teeth) in the US until ~1927. And, pretty much every Tom, Dick, Harry, church, department store and other organization had its own radio station, not to mention thousands of amateurs. So, the concept of staying with any given 'band' was not regulated.

Peter Wieck
Melrose Park, PA

On Tuesday, 27 August 2019 03:22:38 UTC+1, tabby wrote:

A little homemade 1920s 1 valve set with direct heated triode (unmarked). I've traced most of the circuit, looks very simple. Not tried to trace the main coil assembly with its 6 connections yet. The valve has a grid leak resistor for -ve bias without C battery. It runs high R phones, no speaker. 1st question is what sort of HT voltage and/or anode current should I aim for?


NT

From all the replies it seems I don't know much, other than to set it for an Ia of about 2-3mA. It's a 4 pin valve with a modern shaped envelope, so could be anything. I guess it's a dull emitter replacing the original bright.. There's no filament rheostat.

The circuit details are different to the Armstrong version here
https://en.wikipedia.org/wiki/Regenerative_circuit
-it's definitely a reaction set, no doubt there.

Apart from an input cap on the aerial there is NO other fixed cap anywhere in the circuit, so it's going to be horribly unstable, as if PFB on the edge weren't unstable enough already.

I reckon it owes more to 19 teen design than to late 20s, so I expect a very early 20s set. I expect the ae coupling cap, tuning & reaction will all interact some - not to metion headphone wire position affecting feedback as well. It's gonna be a fun one to use.

I presume the coil has a separate winding for the ae, and 2 more winds for the tank & pfb. PFB is controlled by a small varicap.

It got rewired at some point with pvc. Can't imagine why. The connections are all 2mm sockets, which seems anachronistic, but everything else is definitely original.

There's an extra hand wound coil that's only connected at one end. Can't see where it used to connect to. It connects to the ae input after the ae cap, and afaics the circuit ought to work fine without it in. Who knows.

The ae cap pretends to be something else, it's only marked as "the new and improved... stabilizer portable aerial... for better listen" and terminals are marked A & B. Will do some component testing later.


NT

On 2019/08/26 11:44 p.m., Phil Allison wrote:
John Robertson wrote:


Indeed, you need to know the tube value to be sure, but consider the
cost of batteries of the day and thus the B+ is likely 45VDC or thereabouts.

In those days some people made their own B+ batteries - way back when I
was a kid digging through attics in Toronto (mid 1960s) for old battery
sets I found a couple of home-made lead acid batteries that were glass
test tubes about 8 inches long mounted in a wooden box and there must
have been 15 to 20 in each case. Wish I still had them as they were
classic home-brew stuff which I always loved from the battery age of radio.



** The "battery age of (tube) radio" extended well into the 1960s.

Popular "portables" of that era used a pair of 45V packs for B+ and a large 1.5V dry cell for tube heaters - all made by "Eveready".

Miniature 7 pin tubes like the 1S4 and 1R5 were used - along with a transformer supply for home use with a multi-finned selenium rectifier.

https://www.radiomuseum.org/tubes/tube_1s4.html



...... Phil


Yeah, but I was talking about the time when the primary home radio was a
battery set - prior to battery eliminators and the like...

I have a lovely (well, it was lovely at one time, the case needs all new
leather) Radiola 24 which was an early 'portable' radio in my small
collection. About the size of carry-on luggage these days. Cunningham
C-299 tubes...

John :-#)#

After you have handled or been around in the mid-five-figures worth of vintage radios, you will learn not to reason from the specific to the general.

Magic words here a

1920s
Home Brew
Single tube

a) Suspend all other expectations, and deal with what is in front of you.
O1A tubes come in several shapes, from globe to ST. I have seen one (1) "G" type as well, so anything is possible. There are also several other candidates that would do, including an OO, 30 and 112 amongst others. Some would require a different filament voltage. But, the O1A is/was the go-to as they were very common, and much cheaper than the alternatives.

b) Variable capacitors are/were expensive relative to fixed caps. So, your home-brew hobbyist likely picked a fixed cap at some value between that specified for a variable cap.

c) Fixed caps are/were expensive relative to nothing - so your home-brew hobbyist 'went without'. He/She (a great many of the earliest hobbyist were girls/women - why? Most of the parts were made by women). He/She was probably listening to a nearby "torch" station with little or no competition, so targeting to a specific frequency would be typical.

d) At the time, coils were either wound by the hobbyist or purchased to a specific range. If no plug exists, then your hobbyist was uninterested in, or could not afford that option.

e) At the time, there was no 'set standard' for radio parts, connections, hardware nor much of anything else. The typical hobbyist, working on-the-cheap as this one clearly was, would use what was lying around. Which might explain some oddball stuff.

f) Note that the standard for *cheap* wire at the time was rubber/gutta-percha insulation. Which would crumble to dust in short order. So, PVC is no surprise.

On that one-handed coil - are there any taps on it? Commonly, a poor-man's SW or Airplane frequency coil would be done that way - one end fixed, and then tapped to the standard antenna for the alternate.

Summing up, you have the equivalent of a fox-hole radio created with as few expensive parts as possible, following the general idea of the Armstrong circuit, which was 'all the rage' at that time.

Peter Wieck
Melrose Park, PA

On 8/26/2019 9:22 PM, wrote:
A little homemade 1920s 1 valve set with direct heated triode (unmarked). I've traced most of the circuit, looks very simple. Not tried to trace the main coil assembly with its 6 connections yet. The valve has a grid leak resistor for -ve bias without C battery. It runs high R phones, no speaker. 1st question is what sort of HT voltage and/or anode current should I aim for?


NT

The people on this forum will be very knowledgeable and happy to help.
https://antiqueradios.com/forums/index.php

Mikek

On Tue, 27 Aug 2019 09:10:02 -0700, John Robertson
wrote:

On 2019/08/26 11:44 p.m., Phil Allison wrote:
John Robertson wrote:


Indeed, you need to know the tube value to be sure, but consider the
cost of batteries of the day and thus the B+ is likely 45VDC or thereabouts.

In those days some people made their own B+ batteries - way back when I
was a kid digging through attics in Toronto (mid 1960s) for old battery
sets I found a couple of home-made lead acid batteries that were glass
test tubes about 8 inches long mounted in a wooden box and there must
have been 15 to 20 in each case. Wish I still had them as they were
classic home-brew stuff which I always loved from the battery age of radio.



** The "battery age of (tube) radio" extended well into the 1960s.

Popular "portables" of that era used a pair of 45V packs for B+ and a large 1.5V dry cell for tube heaters - all made by "Eveready".

Miniature 7 pin tubes like the 1S4 and 1R5 were used - along with a transformer supply for home use with a multi-finned selenium rectifier.

https://www.radiomuseum.org/tubes/tube_1s4.html



...... Phil


Yeah, but I was talking about the time when the primary home radio was a
battery set - prior to battery eliminators and the like...

I have a lovely (well, it was lovely at one time, the case needs all new
leather) Radiola 24 which was an early 'portable' radio in my small
collection. About the size of carry-on luggage these days. Cunningham
C-299 tubes...

John :-#)#
I had an early 1920s Crosley radio. It had two RCA WD12 tubes which
were retained into their sockets by a rod that projected out of the
tube that was locked into a groove in the tube socket. Tuning was by
a coil on a shaft that one pulled toward or away from a stationary
coil. A multi contact rotary switch selected segments of the AM band.
It used 3 batteries; one for B+, one for the filaments and one for
grid bias. It picked up the 50000 watters in the northeast USA at
night. When I came back home from my first year at a midwest
university, one of my brothers had stolen it and I never saw it again.

On Tuesday, 27 August 2019 17:56:14 UTC+1, wrote:

After you have handled or been around in the mid-five-figures worth of vintage radios, you will learn not to reason from the specific to the general..

Magic words here a

1920s
Home Brew
Single tube

One can't always rule out an amateur builder working to their own outdated technical knowledge. But they clearly know enough to get a radio working, and it's not much more leap to bring the tech up to date.

a) Suspend all other expectations, and deal with what is in front of you.
O1A tubes come in several shapes, from globe to ST. I have seen one (1) "G" type as well, so anything is possible. There are also several other candidates that would do, including an OO, 30 and 112 amongst others. Some would require a different filament voltage. But, the O1A is/was the go-to as they were very common, and much cheaper than the alternatives.

useful to know.

b) Variable capacitors are/were expensive relative to fixed caps. So, your home-brew hobbyist likely picked a fixed cap at some value between that specified for a variable cap.

The one fixed cap on the ae input is in series with a variable cap! I suspect the variable was added later. The other controls are nice & symmetrical then then ae input VC is stuck round the side.


c) Fixed caps are/were expensive relative to nothing - so your home-brew hobbyist 'went without'. He/She (a great many of the earliest hobbyist were girls/women - why? Most of the parts were made by women). He/She was probably listening to a nearby "torch" station with little or no competition, so targeting to a specific frequency would be typical.

My homemade '24 set has lots of caps. But this one is, as you rightly conclude, a total cheapie job. The cabinet is nice but open the lid & it's clearly ill fitted pieces untidily glued together. The rest is similar.

Caps however were almost free. Take some paper & a little foil, tie with cotton & wax it and minutes later you have a cap. Any electronics book of the day explains this. A different history piece I have includes an HV cap made with plywood as the dielectric. I've never seen any graphs on how they perform I guess it's still cellulose.


d) At the time, coils were either wound by the hobbyist or purchased to a specific range. If no plug exists, then your hobbyist was uninterested in, or could not afford that option.

e) At the time, there was no 'set standard' for radio parts, connections, hardware nor much of anything else. The typical hobbyist, working on-the-cheap as this one clearly was, would use what was lying around. Which might explain some oddball stuff.

It has 3 knobs, all clearly of the era but all different. I don't know for sure it was that way originally but it would not surprise me.

f) Note that the standard for *cheap* wire at the time was rubber/gutta-percha insulation. Which would crumble to dust in short order. So, PVC is no surprise.

I thought bare wire was the usual thing to wire up radio internals then.

"Waldo Semon and the B.F. Goodrich Company developed a method in 1926 to plasticize PVC by blending it with various additives. The result was a more flexible and more easily processed material that soon achieved widespread commercial use. "
So it could even be original wiring, though that's not likely.


On that one-handed coil - are there any taps on it? Commonly, a poor-man's SW or Airplane frequency coil would be done that way - one end fixed, and then tapped to the standard antenna for the alternate.

no taps. Looks like it was hand wound round a convenient round object, some sellotape added to keep it together & that was it. It has its own custom mounting made from the same material as the cabinet, so probably was fitted from the start.


Summing up, you have the equivalent of a fox-hole radio created with as few expensive parts as possible, following the general idea of the Armstrong circuit, which was 'all the rage' at that time.

Peter Wieck
Melrose Park, PA

Well, it's a fair bit better than a foxhole set but yes it definitely incorporates some 'whatever' parts, and some not.


NT

On 2019/08/27 2:19 p.m., wrote:
On Tuesday, 27 August 2019 17:56:14 UTC+1, wrote:

After you have handled or been around in the mid-five-figures worth of vintage radios, you will learn not to reason from the specific to the general..

Magic words here a

1920s
Home Brew
Single tube

One can't always rule out an amateur builder working to their own outdated technical knowledge. But they clearly know enough to get a radio working, and it's not much more leap to bring the tech up to date.

a) Suspend all other expectations, and deal with what is in front of you.
O1A tubes come in several shapes, from globe to ST. I have seen one (1) "G" type as well, so anything is possible. There are also several other candidates that would do, including an OO, 30 and 112 amongst others. Some would require a different filament voltage. But, the O1A is/was the go-to as they were very common, and much cheaper than the alternatives.

useful to know.

b) Variable capacitors are/were expensive relative to fixed caps. So, your home-brew hobbyist likely picked a fixed cap at some value between that specified for a variable cap.

The one fixed cap on the ae input is in series with a variable cap! I suspect the variable was added later. The other controls are nice & symmetrical then then ae input VC is stuck round the side.


c) Fixed caps are/were expensive relative to nothing - so your home-brew hobbyist 'went without'. He/She (a great many of the earliest hobbyist were girls/women - why? Most of the parts were made by women). He/She was probably listening to a nearby "torch" station with little or no competition, so targeting to a specific frequency would be typical.

My homemade '24 set has lots of caps. But this one is, as you rightly conclude, a total cheapie job. The cabinet is nice but open the lid & it's clearly ill fitted pieces untidily glued together. The rest is similar.

Caps however were almost free. Take some paper & a little foil, tie with cotton & wax it and minutes later you have a cap. Any electronics book of the day explains this. A different history piece I have includes an HV cap made with plywood as the dielectric. I've never seen any graphs on how they perform I guess it's still cellulose.


d) At the time, coils were either wound by the hobbyist or purchased to a specific range. If no plug exists, then your hobbyist was uninterested in, or could not afford that option.

e) At the time, there was no 'set standard' for radio parts, connections, hardware nor much of anything else. The typical hobbyist, working on-the-cheap as this one clearly was, would use what was lying around. Which might explain some oddball stuff.

It has 3 knobs, all clearly of the era but all different. I don't know for sure it was that way originally but it would not surprise me.

f) Note that the standard for *cheap* wire at the time was rubber/gutta-percha insulation. Which would crumble to dust in short order. So, PVC is no surprise.

I thought bare wire was the usual thing to wire up radio internals then.

There were kit radios of the day that used simple tinned wire. I have
one, a Mercury Super Ten kit (10 'peanut' tubes - superhet) around here
somewhere, but I don't think they are that uncommon.

John :-#)#

On 8/27/19 4:19 PM, wrote:
"Waldo Semon and the B.F. Goodrich Company developed a method
in 1926 to plasticize PVC by blending it with various additives.
The result was a more flexible and more easily processed material
that soon achieved widespread commercial use."

PVC insulation on wires wasn't used until the '40s and was mostly
used by the Government for WWII production.
And even at that, there was plenty of wire that was rubber,
although it was covered in braided cotton.

The standard wire in the 20's was either rubber covered, bare or
"push back" which was solid copper with a spun cotton or silk
covering that could be Just pushed back" so no fuss to expose
the ends of the wires.

So it could even be original wiring, though that's not likely.

Absolutely NOT likely at all in the '20s.


--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com

On Wednesday, 28 August 2019 02:13:15 UTC+1, Fox's Mercantile wrote:
On 8/27/19 4:19 PM, tabbypurr wrote:

"Waldo Semon and the B.F. Goodrich Company developed a method
in 1926 to plasticize PVC by blending it with various additives.
The result was a more flexible and more easily processed material
that soon achieved widespread commercial use."

PVC insulation on wires wasn't used until the '40s and was mostly
used by the Government for WWII production.
And even at that, there was plenty of wire that was rubber,
although it was covered in braided cotton.

The standard wire in the 20's was either rubber covered, bare or
"push back" which was solid copper with a spun cotton or silk
covering that could be Just pushed back" so no fuss to expose
the ends of the wires.

DCC. The homemade coil is enamelled rather than DCC.


So it could even be original wiring, though that's not likely.

Absolutely NOT likely at all in the '20s.

On 8/26/19 10:22 PM, wrote:
A little homemade 1920s 1 valve set with direct heated triode (unmarked). I've traced most of the circuit, looks very simple. Not tried to trace the main coil assembly with its 6 connections yet. The valve has a grid leak resistor for -ve bias without C battery. It runs high R phones, no speaker. 1st question is what sort of HT voltage and/or anode current should I aim for?


NT


Probably intended for a 67 V B battery.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

On Wednesday, 28 August 2019 16:55:29 UTC+1, Phil Hobbs wrote:
On 8/26/19 10:22 PM, tabbypurr wrote:

A little homemade 1920s 1 valve set with direct heated triode (unmarked). I've traced most of the circuit, looks very simple. Not tried to trace the main coil assembly with its 6 connections yet. The valve has a grid leak resistor for -ve bias without C battery. It runs high R phones, no speaker.. 1st question is what sort of HT voltage and/or anode current should I aim for?


NT


Probably intended for a 67 V B battery.

Cheers

Phil Hobbs

Thanks. I may need to make a variable PSU, don't have one that goes high. Or I could just go up in steps with what I've got - that sounds quicker.


NT

On Thu, 29 Aug 2019 02:08:28 -0700 (PDT), wrote:


Thanks. I may need to make a variable PSU, don't have one that goes high. Or I could just go up in steps with what I've got - that sounds quicker.

Just put a few poundland PP3s in series.

On Wednesday, August 28, 2019 at 11:55:29 AM UTC-4, Phil Hobbs wrote:

Probably intended for a 67 V B battery.

Cheers

Phil Hobbs


'Ideal' B+ voltage is determined by the specific tube installed.

Peter Wieck
Melrose Park, PA

On 8/29/2019 5:16 AM, wrote:
On Wednesday, August 28, 2019 at 11:55:29 AM UTC-4, Phil Hobbs wrote:

Probably intended for a 67 V B battery.

Cheers

Phil Hobbs


'Ideal' B+ voltage is determined by the specific tube installed.

Peter Wieck
Melrose Park, PA

I built a two tube radio about 20 years ago using 01A tubes. I put 5
regular 9 volt batteries in series to give 45 volts for the radio.
Worked fine.

You know you can plug the 9 volt batteries + to - using the connectors
on top?

Paul

On Thursday, 29 August 2019 17:56:39 UTC+1, Paul Drahn wrote:
On 8/29/2019 5:16 AM, wrote:
On Wednesday, August 28, 2019 at 11:55:29 AM UTC-4, Phil Hobbs wrote:

Probably intended for a 67 V B battery.

'Ideal' B+ voltage is determined by the specific tube installed.

I built a two tube radio about 20 years ago using 01A tubes. I put 5
regular 9 volt batteries in series to give 45 volts for the radio.
Worked fine.

You know you can plug the 9 volt batteries + to - using the connectors
on top?

Paul

Not a bad idea. They'd last ages too.


NT

On Thu, 29 Aug 2019 22:42:01 -0700, tabbypurr wrote:

Not a bad idea. They'd last ages too.

They sure would. Their combined internal resistances would see to that;
law of diminishing returns and all that. You really need to establish
what the likely anode current will be.
Amazing what they did with just one tube, though! Got to admire the
resourcefulness that went into such designs.



--
This message may be freely reproduced without limit or charge only via
the Usenet protocol. Reproduction in whole or part through other
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protocols constitutes acceptance of this condition.

On Sunday, 1 September 2019 18:52:23 UTC+1, Cursitor Doom wrote:
On Thu, 29 Aug 2019 22:42:01 -0700, tabbypurr wrote:

Not a bad idea. They'd last ages too.

They sure would. Their combined internal resistances would see to that;
law of diminishing returns and all that. You really need to establish
what the likely anode current will be.

2-3mA. PP3s can kick out over 100mA.

Amazing what they did with just one tube, though! Got to admire the
resourcefulness that went into such designs.

Oh yes. Resourceful was the name of the game for a long time, now that silicon's cheap few care about efficiency or smart tricks.


NT

On Sunday, September 1, 2019 at 7:38:46 PM UTC-4, wrote:
On Sunday, 1 September 2019 18:52:23 UTC+1, Cursitor Doom wrote:
On Thu, 29 Aug 2019 22:42:01 -0700, tabbypurr wrote:

Not a bad idea. They'd last ages too.

They sure would. Their combined internal resistances would see to that;
law of diminishing returns and all that. You really need to establish
what the likely anode current will be.

2-3mA. PP3s can kick out over 100mA.

Amazing what they did with just one tube, though! Got to admire the
resourcefulness that went into such designs.

Oh yes. Resourceful was the name of the game for a long time, now that silicon's cheap few care

Maybe "graphene" seems slated as a pseudo-silicon replacement at that, too.