Gyraf G9 TIP121 phantom supply not regulating?

[jwhmca]

Hi Guys,

So I've built the little fancy voltage tripler - TIP121 - 48v Phantom power supply from Gyraf G9 micpre.

I can adjust it up to 48vdc from 15vac, but it won't regulate. Drawing 1-2ma to power LEDs for 48 indication drops the voltage.

I had my LEDs drawing about 20ma total and it was dropping down to 40vdc.

Thoughts?

 

[gyraf]

Don't use phantom power for lightning up a LED?

It's a tripler circuit, not suitable for much current. But does phantom alright.

(And please use the dedicated G9 help thread....)

Jakob E.

 

[johnheath]

I use that specific circuit for 48v pp and it works just great… I also struggled with the wanted led to signal that the pp i "on"… I got that voltage to the led via the regulated 12vdc…just add a 1k ohm resistor in series with the led to bring down the voltage to 2v.

If the led draws 20mA and want 2v of course

/John