Simplistic Mosfet HV Shunt Regs

[ikoflexer]

Originally posted by Salas
Is that horizontal part still double lined if you feed your calibration directly to the scope? Or there is a gremlin....

I'll have to check again tonight. Only the camera got that, with the naked eye I see only one line.

[disco]

Correlation between shutter speed and refresh rate?

[Salas]

Very possible.

[disco]

Last week I did a pcb design for this circuit. Since a couple of days I've got two of them working on a small (2A3) amplifier. They do a good job regulating and sonics are very good. Dynamic, precise but musical I would comment.

There are a few peculiarities about the circuit board.
- when the output is shorted, you'll have to replace the semi's
Some simple alterations can make it fool proof. More on this subject will follow;
- C1 (100uF/10V) is at a high potential. Do not touch while live if the can is not isolated;
- connecting wires shouldn't have excessive length for best results;
- for R2 and R7 it's better not to use metal film;
- R2 is mounted at the back;
- R3 and R9 (in the higher voltage version) are 82K/5W. If you can't locate these there's space to double a 150K/2W and a 180K/2W. These resistors get hot on full 400V!;
- the initial version suffered from heat building up in Q2 so I had to use a heatsink on the small TO-92 transistor. It occurred while the reg was dissipating 45mA at 295V into Q3 (over 13W). This renewed board is more spacious for better air flow around the components;
- if necessary a 47 ohm base stopper on Q2 can be inserted by breaking the copper trace between Q2 and C2 (see purple trace).

Hope you enjoy it as much as I do

[disco]

UNfortunately my file is too big for the forum (740KB). The resolution is 1200DPI for a 10x16cm board (eurocard size). It's located here.

[Salas]

Good tight job. Do you pre filter it? Any optional clamping zeners pads against shorting mishaps? I think you use the Swenson Mosfet HV reg too? Different sonics?

[andRookie]

Originally Posted by disco

UNfortunately my file is too big for the forum (740KB). The resolution is 1200DPI for a 10x16cm board (eurocard size). It's located here.

Can´t get the link to work. Something that can be fixed?

[Salas]

Originally Posted by andRookie

Can´t get the link to work. Something that can be fixed?

The link works in my browser but here it is again, attached.

[disco]

Originally Posted by Salas

Good tight job. Do you pre filter it? Any optional clamping zeners pads against shorting mishaps? I think you use the Swenson Mosfet HV reg too? Different sonics?

Well, experimenting is part of the fun, isn't it?

First tests were on a bench power supply at 345V input, 50mV ripple.
Second I made a 340V PSU with 2.3V ripple (ok, that's a lot).
Last I improved this PSU to 350V with 0.7V ripple (not too good either).
Both PSU's used small caps and a 10H choke, ripple was sinusoidal.
The voltage margin (input to output) was 40 to 50 volts, current margins were circa 50% to 40% (75mA to the load, 40mA to the sink etc).
With all tests I measured no AC at all after the reg.

Regarding the second part of your reply, I'm constructing a straight forward 2A3 amplifier to test the several regulators I've built so far.
There's metalwork involved so it takes some free float to complete.

[disco]

Originally Posted by andRookie

Can´t get the link to work. Something that can be fixed?

The link is OK, the problem might be a temporary unobtainable host because of 'data stress'. If not send me a PM.