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Peter Percival
Guest

Sat Jul 13, 2019 3:45 pm   



Here https://www.rapidonline.com/valves there are a variety of
thermionic valves. Where can I find projects that utilize them? I'll
also need a HT power supply. Any thoughts?

--
"He who will not reason is a bigot;
he who cannot is a fool;
he who dares not is a slave."
- Sir William Drummond

Cursitor Doom
Guest

Sat Jul 13, 2019 10:45 pm   



On Sat, 13 Jul 2019 15:36:21 +0100, Peter Percival wrote:

Quote:
Here https://www.rapidonline.com/valves there are a variety of
thermionic valves. Where can I find projects that utilize them? I'll
also need a HT power supply. Any thoughts?


EHT transformers are getting few and far between at rallies these days.
If you can find say a 240-4kV tranny at 250mA you're all set. But valve
action starts at much lower voltages (sub 100VDC) so you don't *have* to
splash out on some awesome transformer just for experimenting with.



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Peter Percival
Guest

Sat Jul 13, 2019 10:45 pm   



Cursitor Doom wrote:
Quote:
On Sat, 13 Jul 2019 15:36:21 +0100, Peter Percival wrote:

Here https://www.rapidonline.com/valves there are a variety of
thermionic valves. Where can I find projects that utilize them? I'll
also need a HT power supply. Any thoughts?

EHT transformers are getting few and far between at rallies these days.
If you can find say a 240-4kV tranny at 250mA you're all set. But valve
action starts at much lower voltages (sub 100VDC) so you don't *have* to
splash out on some awesome transformer just for experimenting with.


Noted. What now? :-)

--
"He who will not reason is a bigot;
he who cannot is a fool;
he who dares not is a slave."
- Sir William Drummond

default
Guest

Sun Jul 14, 2019 3:45 am   



On Sat, 13 Jul 2019 22:40:44 +0100, Peter Percival
<peterxpercival_at_hotmail.com> wrote:

Quote:
Cursitor Doom wrote:
On Sat, 13 Jul 2019 15:36:21 +0100, Peter Percival wrote:

Here https://www.rapidonline.com/valves there are a variety of
thermionic valves. Where can I find projects that utilize them? I'll
also need a HT power supply. Any thoughts?

EHT transformers are getting few and far between at rallies these days.
If you can find say a 240-4kV tranny at 250mA you're all set. But valve
action starts at much lower voltages (sub 100VDC) so you don't *have* to
splash out on some awesome transformer just for experimenting with.

Noted. What now? Smile


Wind your own plate transformer? Takes a little time to build a small
winder but you're looking for a project, right? Pick the right one to
scavenge and you'd just be winding the secondary. Filament
transformers or DC power supplies are easy enough to find.

I wound a 1 KVA Induction coil/transformer with some 13 miles of 32
AWG in the secondary. Took about a month, but I'd already built a
winder for Tesla coils and modified it to wind multi-layer bobbins.

You can always kludge together some combinations of isolation or
"control" transformers to generate the HT required.

It may take some knowledge and effort to make a switch mode supply or
modify and existing one.

Buy it? http://www.hammondmfg.com/300series.htm

You aren't the only one in the world who wants to do this, so Google
will turn up some things. Do it yourself tube type guitar amps are
pretty popular...

Cursitor Doom
Guest

Sun Jul 14, 2019 10:45 am   



On Sat, 13 Jul 2019 22:34:00 -0400, default wrote:

Quote:
I wound a 1 KVA Induction coil/transformer with some 13 miles of 32 AWG
in the secondary. Took about a month, but I'd already built a winder for
Tesla coils and modified it to wind multi-layer bobbins.


I admire your determination! I have a screw-cutting lathe which is ideal
for this kind of thing. I can just stand there with a reel of wire
putting a little tension on it as it gets unwound and a short time later,
a *perfectly* spaced coil emerges.
The OP could also try microwave oven transformers. He'd have to re-wind
one as they're not much use as they come. But the *are* next to free to
come by from your local recycling centre and ideal for experimenting with.



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default
Guest

Sun Jul 14, 2019 1:56 pm   



On Sun, 14 Jul 2019 08:45:57 -0000 (UTC), Cursitor Doom
<curd_at_notformail.com> wrote:

Quote:
On Sat, 13 Jul 2019 22:34:00 -0400, default wrote:

I wound a 1 KVA Induction coil/transformer with some 13 miles of 32 AWG
in the secondary. Took about a month, but I'd already built a winder for
Tesla coils and modified it to wind multi-layer bobbins.

I admire your determination! I have a screw-cutting lathe which is ideal
for this kind of thing. I can just stand there with a reel of wire
putting a little tension on it as it gets unwound and a short time later,
a *perfectly* spaced coil emerges.
The OP could also try microwave oven transformers. He'd have to re-wind
one as they're not much use as they come. But the *are* next to free to
come by from your local recycling centre and ideal for experimenting with.


I'd spend evenings watching TV and winding. With every layer I'd coat
the wire with varnish and have to wait for it to dry. I had a turns
counter and was coming up 10% short of the theoretical or nominal
turns-per-inch so I increased the layers to compensate. By measuring
the resistance, the secondary was ~300 feet over my calculations.

The idea of microwave transformers is a good one. I notice they've
begun welding the laminations in a strip along one side. But one of
those cheap angle grinders from Harbor Freight would make quick work
of that for disassembly.

The weld is probably to keep the laminations from buzzing, but one
upside is there's no varnish to glue the laminations together.

And he says nothing of what he wants to build, chances are it wouldn't
require the iron of a MOT to carry the VA required. Then too we had
some Delco car radios back in the stone ages that used 12V for the
plates of the tubes and a big old (Germanium PNP) transistor for the
output with a small tapped inductor to match impedance.

Several tube radio schematics and a few that use 12V for the plate
supply:

http://makearadio.com/tube/tube-radio-schematics.php

another

https://www.nutsvolts.com/magazine/article/may2015_Whipple

Tubes to do the magic and transistors for the heavy lifting.

Cursitor Doom
Guest

Sun Jul 14, 2019 3:05 pm   



On Sun, 14 Jul 2019 07:56:06 -0400, default wrote:

Quote:
https://www.nutsvolts.com/magazine/article/may2015_Whipple

Tubes to do the magic and transistors for the heavy lifting.


Great project idea, but there's a dastardly IC lurking in there! I'm a
bit puritanical when it comes to this kind of thing so if I were to build
it, which sadly I don't have time to do, it would have to be *all*
discretes for me, I'm afraid.



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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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Peter Percival
Guest

Mon Jul 15, 2019 3:45 pm   



default wrote:
Quote:
On Sun, 14 Jul 2019 08:45:57 -0000 (UTC), Cursitor Doom


Quote:

And he says nothing of what he wants to build,


That's a good point! It may be that I won't know until I get started,
but how about

Valve voltmeter; oscillators (Hartley, Colpitts,...); power supply; SW
receiver.

Suggestions grateful received.

Quote:
chances are it wouldn't
require the iron of a MOT to carry the VA required. Then too we had
some Delco car radios back in the stone ages that used 12V for the
plates of the tubes and a big old (Germanium PNP) transistor for the
output with a small tapped inductor to match impedance.

Several tube radio schematics and a few that use 12V for the plate
supply:

http://makearadio.com/tube/tube-radio-schematics.php


There's plenty there that looks doable by a beginner.

Quote:
another

https://www.nutsvolts.com/magazine/article/may2015_Whipple

Tubes to do the magic and transistors for the heavy lifting.



--
"He who will not reason is a bigot;
he who cannot is a fool;
he who dares not is a slave."
- Sir William Drummond

default
Guest

Mon Jul 15, 2019 4:45 pm   



On Mon, 15 Jul 2019 15:14:11 +0100, Peter Percival
<peterxpercival_at_hotmail.com> wrote:

Quote:
default wrote:
On Sun, 14 Jul 2019 08:45:57 -0000 (UTC), Cursitor Doom



And he says nothing of what he wants to build,

That's a good point! It may be that I won't know until I get started,
but how about

Valve voltmeter; oscillators (Hartley, Colpitts,...); power supply; SW
receiver.


I'd stay shy of the valve voltmeter, that would be fairly daunting
even back in the day. https://tinyurl.com/yy56t4nl is the schematic
for RCA's "VoltOhmyst." Good luck sourcing those multilayer wafer
switches or a nice panel meter that you could make a scale for...

Likewise the oscillators are easily doable, but what's the point? Just
to look at the trace on an oscilloscope? You could, of course, build
a small AM or FM transmitter based on an oscillator, being mindful of
the regulations you might run into. In the US most of that stuff
falls under part D of the FCC regulations, and even then you aren't
allowed to interfere with other services.

Check out "phono oscillators" if that's your thing.

Power supplies used tube types 5Y3, 5U4, 6X4 if my memory serves, they
often used center tap full wave bridge circuits and made use of the
common cathode running on it's own dedicated filament winding (which
was often floating at the HV potentials) Much easier and cheaper to
use rectifier diodes today. Even the purist "audiophiles" stoop to
using solid state rectifiers in their tube circuits.

The HV source itself can be generated with a high frequency
transistor oscillator too; you don't absolutely need a "plate
transformer," unless it is for aesthetic reasons.

A lot of the old designs ran directly off the power lines and used no
isolation transformers. In those circuits they used tubes that had
high voltage filaments and the filaments were wired in series.
http://www.angelfire.com/electronic/funwithtubes/AA5-1.html
Quote:

Suggestions grateful received.

chances are it wouldn't
require the iron of a MOT to carry the VA required. Then too we had
some Delco car radios back in the stone ages that used 12V for the
plates of the tubes and a big old (Germanium PNP) transistor for the
output with a small tapped inductor to match impedance.

Several tube radio schematics and a few that use 12V for the plate
supply:

http://makearadio.com/tube/tube-radio-schematics.php

There's plenty there that looks doable by a beginner.


Bear in mind some of those schematics use some truly ancient tube
types. Good luck finding some 30 series valves, for instance... or
sockets to put them in.

But I do agree, there's a lot fun stuff there to tinker with.
Super-regenerative radios worked very well. They may have lacked the
selectivity of super-het designs but they were sensitive and used far
fewer parts.

You mention beginner and to me that looks like a good place to start.
Quote:

another

https://www.nutsvolts.com/magazine/article/may2015_Whipple

Tubes to do the magic and transistors for the heavy lifting.

There may be some kits available. There's a wealth of information on
line for old radio and audio circuits using valves.

Ebay phono oscillator kit (kits - scroll down too)
https://tinyurl.com/y32tbevv

There's several tube type audio kits.

Peter Percival
Guest

Wed Jul 17, 2019 9:45 pm   



default wrote:


Quote:
And he says nothing of what he wants to build, chances are it wouldn't
require the iron of a MOT to carry the VA required. Then too we had
some Delco car radios back in the stone ages that used 12V for the
plates of the tubes and a big old (Germanium PNP) transistor for the
output with a small tapped inductor to match impedance.

Several tube radio schematics and a few that use 12V for the plate
supply:


Where is a good place to buy such things?

Quote:
http://makearadio.com/tube/tube-radio-schematics.php

another

https://www.nutsvolts.com/magazine/article/may2015_Whipple

Tubes to do the magic and transistors for the heavy lifting.



--
"He who will not reason is a bigot;
he who cannot is a fool;
he who dares not is a slave."
- Sir William Drummond

default
Guest

Wed Jul 17, 2019 11:45 pm   



On Wed, 17 Jul 2019 21:30:45 +0100, Peter Percival
<peterxpercival_at_hotmail.com> wrote:

Quote:
default wrote:


And he says nothing of what he wants to build, chances are it wouldn't
require the iron of a MOT to carry the VA required. Then too we had
some Delco car radios back in the stone ages that used 12V for the
plates of the tubes and a big old (Germanium PNP) transistor for the
output with a small tapped inductor to match impedance.

Several tube radio schematics and a few that use 12V for the plate
supply:

Where is a good place to buy such things?


I don't know. You can find odds and ends and kits on ebay. But the
people doing it today are filling an emotional need IMO. The effort
and meticulous attention to detail suggests it's more a labor of love.

I've fixed a few old radios that people brought to me and it's a hunt
to find parts for them.

https://antiqueradio.org/parts.htm

http://www.surplussales.com/equipment/hamequipment/AntqRadPrts.html

https://www.radiomuseum.org/forum/north_american_suppliers_for_vintage_electronics_28_nov_11.html

http://vintage-electronics.com/

https://www.oldradioparts.net/

https://www.tubesandmore.com/

Amateur radio swap meets are a good source of interesting stuff.

Search on boat anchor radio - those words, not the phrase
Quote:


S Deyoreo
Guest

Sat Jul 20, 2019 2:45 am   



On Saturday, July 13, 2019 at 10:36:24 AM UTC-4, Peter Percival wrote:
Quote:
Here https://www.rapidonline.com/valves there are a variety of
thermionic valves. Where can I find projects that utilize them? I'll
also need a HT power supply. Any thoughts?

--
"He who will not reason is a bigot;
he who cannot is a fool;
he who dares not is a slave."
- Sir William Drummond


As a kid, I used to use a 90v battery for the plate supply. Opened it one day and it was 10 9v batteries! Remember Burgess Battery?

Cursitor Doom
Guest

Sat Jul 20, 2019 2:45 pm   



On Fri, 19 Jul 2019 17:48:22 -0700, S Deyoreo wrote:

Quote:
As a kid, I used to use a 90v battery for the plate supply. Opened it
one day and it was 10 9v batteries!


You sound surprised.





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This message may be freely reproduced without limit or charge only via
the Usenet protocol. Reproduction in whole or part through other
protocols, whether for profit or not, is conditional upon a charge of
GBP10.00 per reproduction. Publication in this manner via non-Usenet
protocols constitutes acceptance of this condition.

Ralph Mowery
Guest

Sat Jul 20, 2019 3:45 pm   



In article <qgv46c$4vi$1_at_dont-email.me>, curd_at_notformail.com says...
Quote:

As a kid, I used to use a 90v battery for the plate supply. Opened it
one day and it was 10 9v batteries!

You sound surprised.



Sometimes you never know what is actually inside a battery larger than
the nominal 1.5 volts.

I have seen 9 volt batteries containing 6 cells that look about like aaa
batteries and some that have 6 stacked flat caseless (wraped in plastic)
cells. The old 6 volt lantern battery was 6 large 1.5 volt cells. I
have not opened up the newer ones, but have seen youtubes where they
have lots of AA or so cells in them.

Peter Percival
Guest

Sat Jul 20, 2019 6:45 pm   



Peter Percival wrote:
Quote:
Here https://www.rapidonline.com/valves there are a variety of
thermionic valves.  Where can I find projects that utilize them?  I'll
also need a HT power supply.


For the latter, I though building my own would be a good idea. And if
building one is a good idea then building two must be twice as good. Thus -

(a) http://www.pmillett.com/HV_bench_supply.htm;
(b)
http://www.arrl.org/files/file/QST/This%20Month%20in%20QST/August%202014/JULSTROM.pdf.

The worst that can happen is that I'll electrocute myself.

Quote:
  Any thoughts?



--
"He who will not reason is a bigot;
he who cannot is a fool;
he who dares not is a slave."
- Sir William Drummond

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