I'm working through a paper design based on compactrons with non-standard heater voltages.
Were any small signal dual triodes with 21 or 31 volt heaters ever made? I searched but came up empty handed.
Thanks and regards,
Rob
Were any small signal dual triodes with 21 or 31 volt heaters ever made? I searched but came up empty handed.
Thanks and regards,
Rob
Not likely. The odd voltages were used to get a particular current for series string operation, usually 450mA or 600mA. The high voltages are used for power tubes that need a lot of heater power. So a low power tube will have a low voltage rating.
I doubt that there are any dual triodes in a compactron, only triples and maybe a dual plus something else (diodes or a pentode, maybe). Usually 8V to 11V heaters for these, or 6 or 12V.
Pete
I doubt that there are any dual triodes in a compactron, only triples and maybe a dual plus something else (diodes or a pentode, maybe). Usually 8V to 11V heaters for these, or 6 or 12V.
Pete
For RF amplifiers and mixers in FM receivers but a dual triode with 21V/100mA heater. And the heater is meant for series connection.
UCC85.
Ah, the old brain. The heater is 26V
UCC85.
Ah, the old brain. The heater is 26V
ECC85 is similar to 12AT7. And there's 20EZ7 for a 12AX7 equivalent - again, a 9-pin (noval) not a Compactron. I'm not sure if there were ANY 100 mA or 150 mA heaters for Compactrons...
20EZ7 might work. Tube does not need to be a compactron. The idea is more like Christmas tree lights -- 6 heaters in series at 21V each gets pretty darn close to line voltage, i.e., no filament transformer required.
Thanks and regards,
Rob
Whatever else you do, stop. Don't ever connect any part of your circuit to the mains supply without an isolating transformer. Your life, or someone else's may depend upon a safe connection.
Discussion of direct connection is banned on this forum.
You can NOT connect heaters in series unless they ALL have the same CURRENT rating. The voltage doesn't matter as long as they all add up to the output of your transformer. I have built several guitar amps that run entirely from a single 120 volt isolation transformer.
The smallest uses a $12 Triad N-68X to power a 4 tube amp using a pair of 32ET5's, an 18FW6, and an 18FY6 plus a resistor all wired in series. These are all 100 mA tubes. The amp makes about 8 watts.
I built a bigger amp that used a pair of UL84's (45B5) and a pair of 20EZ7's modeled after an 18 watt Marshall circuit. It used a 100VA isolation transformer that cost about $20. B+ came from a voltage doubler on the transformer secondary.
You must use a transformer to connect any type of electronics to the power lines, even tube heaters. I know there were zillions of transformerless tube amps and radios made in the past.....and they KILLED people. Heater to Cathode shorts are not uncommon in tubes. This can connect your guitar, turntable, or CD player DIRECTLY to the power lines if you don't use a transformer. Would you stick a metal knife into the wall outlet while holding it?
Oh, I forgot KCL. I missed that about constant current. This idea won't work, then.
Didn't know about the h-k failure mode, either. Difficult to surmount that one. Thanks for the education!
No, or at least with only one hand and insulating footwear.
Regards,
Rob
I would never stick a knife into a US wall outlet.....It doesn't fit. It was a paper clip! I was about 5 years old and it started this 55+ year fascination with electricity.
The ole' paperclip in the wall outlet put an end to many boring science class lectures at my old highschool 😉... Until the teacher caught on to why the fuse kept blowing every time he was using the overhead projector.
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