Simplistic MosFET HV Shunt Regs

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10V in-out drop is good for the CCS and 20V is recommended so to ensure the 10V bottom level for somewhat varying mains during the day or from place to place average. Anymore than 20V is no problem as long as its not producing much heat along the CCS setting in mA.
 
SSHV1

Salas,

The voltage on my SSHV1 is drifting lately. The supply voltage is 217v. It starts at about 100v at the output then slowing drifts the way up to around 145v ( this is my desire voltage for the 26 B+ ) then drifting up and down. I have tried changing the 350, 840 and even all 4 12v zeners with no avail. Will it be the problem on the 9610 / or the 170 ??

Albert
 
Salas,

The voltage on my SSHV1 is drifting lately. The supply voltage is 217v. It starts at about 100v at the output then slowing drifts the way up to around 145v ( this is my desire voltage for the 26 B+ ) then drifting up and down. I have tried changing the 350, 840 and even all 4 12v zeners with no avail. Will it be the problem on the 9610 / or the 170 ??

Albert

try replacing the mpsa92
 

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diyAudio Chief Moderator
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Was MJE350 getting particularly hot for long periods before the excess drift appeared recently? Does it have some sort of sinking?
Is the 170 in hot environment? Provide it with some heat relief. A little foil or special TO-92 sink. If you will blow over the 170 while watching Vout you will know.
 
Was MJE350 getting particularly hot for long periods before the excess drift appeared recently? Does it have some sort of sinking?
Is the 170 in hot environment? Provide it with some heat relief. A little foil or special TO-92 sink. If you will blow over the 170 while watching Vout you will know.

My mistake not checking the temperature on the 350, but now they're all new. I didn't put any sink onto them, I'll try doing this if it's necessary. No sink for 170 either.
 
If the temperature inside the case varies, then adding a sink to the jFET will drag the jFET Tc & Tj along with the varying Ta. It will make tempco worse not better.

However, the temperature inside the case should be reasonably stable. This will allow the jFET to hold it's own temperature ~ 1Cdegree above Ta.