Well, the boards are in, but I don't like the results -- all of the work is done by the 1K resistor -- and if the B+ on the input rises to, say, 400V the current limiter formed by the LM317/120R resistor seems to fail at its job and we start to get white smoke. Kind of like the old joke -- looks good feels bad (1). Even without the filter caps, and extensive zener filtering the output looks very clean indeed, but it just doesn't regulate. I also had a design error which was my fault -- this was easy enough to correct. A couple folks sent $ to my PayPal account which I have returned. I don't want to disappoint.
(1) This joke is not to be repeated in "pleasant company" and I repeat it not here for fear of the sin bin.
(1) This joke is not to be repeated in "pleasant company" and I repeat it not here for fear of the sin bin.
I rewired with BU208A instead of the MJE3439 -- once the devices get cooking (I see about 25 ma out of the power supply -- 12 ma for the zeners and 13 ma for the load resistor) the voltage creeps up from 284 to 308. I am using 5 watt zeners so they aren't getting fried.
There was a small error on the board -- not difficult to fix but it p*sses me off that I made a stupid mistake -- too much hubris. I wanted to move the zener string to a location where it would get some ventilation -- certainly not a problem if you are using a TO-3 pass transistor.
I have your address and will send a pair of boards -- let me know how you do.
There was a small error on the board -- not difficult to fix but it p*sses me off that I made a stupid mistake -- too much hubris. I wanted to move the zener string to a location where it would get some ventilation -- certainly not a problem if you are using a TO-3 pass transistor.
I have your address and will send a pair of boards -- let me know how you do.
An externally hosted image should be here but it was not working when we last tested it.
Here's a graph of V(in) X-Axis) vs V(out) -- and Zener Current (Left Y-axis) -- etc., etc.:
An externally hosted image should be here but it was not working when we last tested it.
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