sae-7125
Super Member
few words of caution about the above circuit, if built and powering the tube circuit.
due to the senselessly high ladder bias i started with, the bottle load is slow to wake up. which results in zener limiter stress (5w used each) for longer than desired. thermal camera helps to protect the situation and reduce any potential kaboom outcome.
the voltage-doubler front end is being used as a reducer/throttle due to the excessively high mains txf output. also notice that the circuit is only using half-tap of the high-tension secondary. series resistor with parallel cap on the v-doubler front end is a work in progress experiment which ultimately could be deleted down to a single cap on either rail (pre b+ and gnd).
the 1nf off of darlington base is variable up to around 100nf before output load ripple starts to be affected. initial design parameters were to be around 100uv RMS +/- 100uv or somewhere below 1mv RMS as an extreme starting point.
the newer/latest circuit version has more b+ and balanced load along with cold-start test slider. one easy solution for the slow heater wake-up is to use a time delay relay for the b+ circuit specifically. i havent figured out a capacitance throttle yet, using mosfet or igbt or vfet or something which would be quite useful. thermal feedback from zener limiter could also adjust the front end capacitance for a safe circuit design but havent made progress in that direction.
more starting point analysis needed but trying to refrain from feature creep, too many design options too soon, before stable v1.0 is achieved. its a work in progress type of thing.
due to the senselessly high ladder bias i started with, the bottle load is slow to wake up. which results in zener limiter stress (5w used each) for longer than desired. thermal camera helps to protect the situation and reduce any potential kaboom outcome.
the voltage-doubler front end is being used as a reducer/throttle due to the excessively high mains txf output. also notice that the circuit is only using half-tap of the high-tension secondary. series resistor with parallel cap on the v-doubler front end is a work in progress experiment which ultimately could be deleted down to a single cap on either rail (pre b+ and gnd).
the 1nf off of darlington base is variable up to around 100nf before output load ripple starts to be affected. initial design parameters were to be around 100uv RMS +/- 100uv or somewhere below 1mv RMS as an extreme starting point.
the newer/latest circuit version has more b+ and balanced load along with cold-start test slider. one easy solution for the slow heater wake-up is to use a time delay relay for the b+ circuit specifically. i havent figured out a capacitance throttle yet, using mosfet or igbt or vfet or something which would be quite useful. thermal feedback from zener limiter could also adjust the front end capacitance for a safe circuit design but havent made progress in that direction.
more starting point analysis needed but trying to refrain from feature creep, too many design options too soon, before stable v1.0 is achieved. its a work in progress type of thing.
