Quote:
Originally Posted by bandersen
LOL I didn't go above 8 volts so I think it'll be alright  |
Has anyone measured the volts/current it pushes through the filament during the auto restore and auto rejuvenate cycles? I'm wondering if it just adds X volts to the currently selected filament voltage, jumps to a predetermined value, or if it goes into a constant current mode of some sort. I can't recall if you ever performed either cycle on a weirdo 2.xx volt predicta tube or not. I'm imagining it does the opposite of the life test button.
Speaking of constant current, in sets that have had the diode, or diode+resistor mod done to the filament string, since the filaments are now only seeing a DC voltage, why not chuck in an LM317 in current limit configuration using a 2.1 ohm 1 or 2 watt resistor to hard clamp the cold inrush current to a max of 595ma, slightly faster warmup than a thermistor, with the added benefit of auto compensating for higher than planned line voltages. (Might want to use an LM350 or an LM338, I'll admit to not yet having crunched the full numbers in terms of TDP, etc but if your diode mod gets it to 10v or less over target, at ideal 117v, the regs are unlikely to fry even if you plugged it into a 130v source.)