Bleed down resistor

[stretchneck]

What would be the purpose of the relay?

Personally, I set up the bleeders to draw about 2-3 mA at full B+. The supply will discharge in 15~20 seconds if an amplifier is hooked up. Much, much slower if the amp is not connected to the supply.

~Tom

Hi Tom - I think you should include this in your Power-86 and 686 manuals. Also a photo on identification of LED polarity.

 

[tomchr]

Sure. I can do that.

As for identifying the polarity of a LED: The best place to look is in the data sheet for the LED. All LEDs I've come across so far have had one long pin and one short pin. The short pin is the cathode. You can see that in the second image on the Wikipedia page for LEDs: https://en.wikipedia.org/wiki/Light-emitting_diode

Tom

 

[lcsaszar]

I use a bleeder resistor (actually a voltage divider) that is permanently part of the circuit. It sets the g1 voltage of the upper tube of a cascode stage, and draws about 1mA. And I trained myself not to touch the internals for about 3 to 4 minutes. Plus I measure the B+ before doing anything on the amplifier. If it falls below 10V then I consider it safe.
Actually I have a separate switch for the heater/negative bias and for the B+. Self-discharge of B+ is much faster if I leave the heater/negative bias on.