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Tubekarus75 3rd January 2013 03:11 PM

Help Needed - Rebuilding a Darling amplifier power supply
hi folks! i want to rebuild a Darling amplifier power supply.

here you see the original one...

i want to replace the Zener diodes by using stabilizer tubes. I have a lot of 0a3,0b3, 0c3 and 0d3 available. the reason i want to do this is ti have a more spectecualr look.

Is it possibel to usa a 0C3 and 0D3 in series? How to calc. the necessary resistor so that tthe tube/valve will work properly?

Many thanks

payloadde 4th January 2013 06:29 PM

picture is too small, can't read anything ...

Tubekarus75 4th January 2013 06:32 PM

look here please... Bilder-Upload - Kostenlos Fotos hochladen und ins Netz stellen

Ketje 4th January 2013 07:48 PM

If it's only for the looks,let the circuit as it is.The stabilisertubes will glow with a series resistor connected on the capacitor just after the rectifier.They only need 5mA.

payloadde 5th January 2013 07:48 PM

In principle you could series string OB3 (90V) + OD3 (150V) and change 10K to 3.3K to get 10mA - 5mA is data-sheet minimum but my experience is that these neon stabilizers need at least 10mA to be happy.
However you may not have enough voltage to ignite them - it takes 300V+ and I estimate you have only 275V or so ... they may fire up, or not if mains voltage is low. The problem is when they don't fire, the output of your regulator will be equal to the input voltage i.e. 275V. Not good ...
You could possibly replace just one of the zeners e.g. the 110v by OC3. If you keep the 10K R it will not get enough current. 3.3K again gives you 10mA but now the 140v zener will dissipate 1.4W. Can it take that ?
In any case if you used neon stabis don't forget to replace the 50uF cap with 50nF ! >They oscillate when bypassed by more than 0.1uF.

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