This post isn't a question, or an assertion. Its just a cute little circuit I came across for someone wanting the heat a DH tube with a battery where the battery is switchable between run or charge. I thought it was clever enough to file it, so sharing. Credit goes to vt52.com.
I'd recommend caution unless an additional LVDO was added to avoid battery discharge below accepted minimum level where often permanent damage can occur to the battery.
Yeah that, and I think the charging side of the circuit can be improved with some current limiting too, the LM317 app notes have some battery charging Circuits. A battery health monitoring board might be available too as a drop in. Or maybe a 5200 mAh lithium RC car battery and off the shelf charger.
https://www.amazon.com/Zeee-Batteri...hvlocphy=&hvtargid=pla-4583657821813951&psc=1
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It seems like a very nice idea to use a battery as filament supply. Guaranteed hum free and simple. With a 4 Ah battery, there is almost no risk of running out of power in a listening session. I haven't seen this approach used before. Is there any drawback sound wise?
Yes it is and this was invented more than 100 years ago.
But it is not very sophisticated to use 6 v battery for heating 1.2 v filament.
1G4 at 50mA is C/80 for 4Ah so large, and up to 270mW dissipation in the 317T is easy and should allow high current short-duration heater startup. 6V 4Ah PbAcid is very common, and useful on the bench for other test purposes.
I know that batteries was used to power tubes in ancient times, including anode supply. I should have written, that I haven't seen it used in contemporary hifi gear.
makes sense, you wouldn't need the second Regulator and can use a simple current limiter on the charger side. Safer than lithium for sure.
Could work for many 1v tubes that could tolerate excess voltage. But for 1G4 it is a tube where the Filament will burn out fast with even a slight over voltage, it has a very thin 50ma Filament. 2v will probably fry it. So a 2v battery may not be enough overage for a LDO reg. or you'd need a resistor. But I'm sure many other 1v tubes with fatter Filaments would be fine with 2v. 🙂 Nice battery 95% recharge in less than an hour, lead acid like a car! I could see a CCS trickle charger that turns on when you turn off the amp.
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