R1 is 56ohm, my application is for a phono preamp using 250V and 55mA with CLC filtered output 300V
Same ones. Was final testing the filament shunt regs and when completed, I plugged in the high tension umbilical cable. Just as I was inserting the the plug it dawned on me that the voltage would probably be too high for the parts. The sound, and smell confirmed my thinking. Lesson learned.
What is the voltage across the 56 Ohm? Your 8K6 dummy draws 30mA @ 270V.
I bought at RS on line by internet, fisical shop is in Barcelona 60Km aprox. of where I live, the other times I bought something never any trouble.
Can I replace irf9610 for irf9240, remove the heatsink for one biggest or left the same heatsink like used for irf9610
Bad move, and it was working fine all along, grief. What the heck, make it into SSHV2 is an opportunity.
Don't know more Merlin. Its the classic SSHV1 circuit as you know it. If executed OK, then it does not like something in that configuration that I can't understand from afar.
The voltage across the 56ohm is 1.836V. confirm the load again is 262.6V with 8K6 dummy load.
Merlin
Can you show us the wiring diagram of your test circuit? and a photo showing your p2p at the back side of your PCB.
That 1.836/56 confirms 32mA available. All logical again, smaller dummy won't let it hold. You would need ~75mA (VR1/R1=CCS) for feeding 55mA to your phono. Your sinks look small for that. But, are you sure your phono takes 55mA and not far less? Sounds much for a tube phono.
My pre-amp is the Toccata Phono. I measure the current with my unregulated PSU which has 280V o/p and the pre-amp draw 51.5mA. For 75mA, should I need a smaller R1 or larger VR1?
For my SSHV1 I have a huge oversized heatsink 3"Hx8"L with 22 x 1.5" fins.
But the heatsink barely gets warm, and probably due to my mosfet mounting the output mosfets get around 100C, they are dissapating ~4W each. Is this 100C OK?, or should I look at improvement my mount to the heatsink which currently has the thin aluminum rear case panel in between.
My next module will be with SSHV2 will be the same case and heatsink config but potentially more bias current for the tube as this will be parafeed and I won't be limited by the OPT as the previous design.
But the heatsink barely gets warm, and probably due to my mosfet mounting the output mosfets get around 100C, they are dissapating ~4W each. Is this 100C OK?, or should I look at improvement my mount to the heatsink which currently has the thin aluminum rear case panel in between.
My next module will be with SSHV2 will be the same case and heatsink config but potentially more bias current for the tube as this will be parafeed and I won't be limited by the OPT as the previous design.
In that case, I would make another one the same reg for double mono both with 47R R1, because with your construction space and sinks, if you will crank the CCS to 70-75mA (extra to 50mA load is for the reg to work well) I don't see it will hold thermally well.
100C is too much on so big sinks. Look for around 45-55C on Mosfet case for long term reliability.
Salas, is spot on with his recomendation. With that current level much better using dual mono and big heat sinks. My SSHV regs live on these sinks. 1 reg per sink passing 70mA total current with 345V Input. 310V output. Load is 30mA.
The heatsinks stay comfortable warm but are warm non the less. ABout 45-50C in 28C room
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Nick is IRFP9240 or IRF9240? with IRFP9240 also burned 220R gate resistor.
I don't have IRF9240 I have IRF9610 from minikits of Mike aka Tea-Bag are also Vishay (Intersil) like the ones I bought to RS.
Also I have:
IRF610
IRF950
IRF9540
IRFP9140
George suggested to put before the reg 500R in series with the positive, I have two 270R 1R so in parallel 540R, it's a good idea to use it?
I don't have IRF9240 I have IRF9610 from minikits of Mike aka Tea-Bag are also Vishay (Intersil) like the ones I bought to RS.
Also I have:
IRF610
IRF950
IRF9540
IRFP9140
George suggested to put before the reg 500R in series with the positive, I have two 270R 1R so in parallel 540R, it's a good idea to use it?
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You could relax it to 50mA CCS for 30mA load, is enough. Those in picture are the ones now knocking on heaven's door BTW? Both, or just one had the plug?