I was wondering if there was a simple way to do this .
Essentially mimic the way a tube rectifier slowly ramps up the Ht at turn on ,
Could we dump current at switch on for maybe 30-60 seconds , meanwhile the power supply C|R|C networks take time to charge up .
If we had a resistor and thermistor( lo-hi resistance )PTC? in series across the Ht supply then another thermistor(NTC) in series with the smoothing filters would that work?
Lets assume a passively smoothed HT with CRCRCR filter , 220uf caps and resistances in the order of a few kilo-ohms .
Could we incorporate NTC thermistors into the HT bridge rectifier circuit in such a way that initially they drop a lot of volts and only allow the reservoir and filter caps fill slowly.
I know theres HT delay systems involving relays they still spike the HT on the caps and tubes although the heaters will have had time to warm , or maybe some kind of mosfet that soft starts things but I'd much rather a way to do it simply, passively , two legged components only .
'It should also be noted that valves actually last longer if they have some cathode current flowing while they are heated, which again is contrary to the theory of the standby switch. Source: Radio Designer's Handbook, 4th edition'
Essentially mimic the way a tube rectifier slowly ramps up the Ht at turn on ,
Could we dump current at switch on for maybe 30-60 seconds , meanwhile the power supply C|R|C networks take time to charge up .
If we had a resistor and thermistor( lo-hi resistance )PTC? in series across the Ht supply then another thermistor(NTC) in series with the smoothing filters would that work?
Lets assume a passively smoothed HT with CRCRCR filter , 220uf caps and resistances in the order of a few kilo-ohms .
Could we incorporate NTC thermistors into the HT bridge rectifier circuit in such a way that initially they drop a lot of volts and only allow the reservoir and filter caps fill slowly.
I know theres HT delay systems involving relays they still spike the HT on the caps and tubes although the heaters will have had time to warm , or maybe some kind of mosfet that soft starts things but I'd much rather a way to do it simply, passively , two legged components only .
'It should also be noted that valves actually last longer if they have some cathode current flowing while they are heated, which again is contrary to the theory of the standby switch. Source: Radio Designer's Handbook, 4th edition'