The simplistic Salas low voltage shunt regulator

[AndrewT]

measure your GRs and find out which ones are at which end of the tolerance range.
You may find that some are pretty close to BLs.

Select the current of each FET to suit the location it is in.
They all do a different job and as a result they can all pass a different current.

[jkeny]

Thanks Andrew & I'm sorry if I'm being lazy or dumb but is there a schematic with the currents shown at the Fets?

[Salas]

Originally posted by jkeny
Is 170BL needed in these regulators or will 170GR do?

I ask because of the difficulty of obtaining 170BLs & I have 170GRs already!

GRs towards 5mA IDSS are fine both for low pinch off and for stiffening the Zener enough.

[iko]

In principle it should work. Easy for you to try since you have the parts. Go for it.

[iko]

Originally posted by jkeny
Thanks Andrew & I'm sorry if I'm being lazy or dumb but is there a schematic with the currents shown at the Fets?

jkeny, the current through the jfets is generally dependent both on the voltage across them (drain/source pins) and also, when gate and source connected together, to the device itself (Idss). But in the salas regulator the voltage across is large enough for each jfet location that it is the Idss of the device itself that will set the current through it. Therefore, measure your jfets, easily done this way: connect the gate and drain (pins 2 and 3) together to the positive lead of your digital multimeter set on 20mA range. The common (black) lead of the DMM to - 9V (battery), and pin 1 of the jfet (drain) to + 9V. Do not hold the jfet in your hand, as Idss is very temperature dependent. Then wait for a bit until the current shown stabilizes. That's your Idss, and that's about the value that you can expect to have in the circuit. Choose the higher current GRs for your circuit.

[disco]

- description -

[nicoch58]

HI Salas , on phono you have tried
some pre reg or heavy passive filter before shunt ??

[disco]

It seems there's a limit to the actual number of pixels to be uploaded...
Anyway, the file can be had here. It's a 1200dpi drawing, three of them fit in a regular eurocard format (10x16cm).

The backside along with its components.

[nicoch58]

and for my shunt as I have to much Vin (heat)
...

[AndrewT]

Nicoch,
give us a clue.
Vin=?
Vout=?
Iout=?