Bleeder Resistor

[davidhugo]

Hi

I have built a 30 v PSU for a chip amp I have built building it has 40,000uf of smoothing.
This bank of capacitors stays charged which is rather dangerous as I am still adjusting the amp.
What value ohms and watts would I need for a bleeder resistor? There’re 4 capacitors in the PSU.
Am I right in thinking I can just use one resistor across the leads going to the amp.

Any help would be very much appreciated

David

[bobodioulasso]

2k2 3w is usual value.
An other way to empty the caps is to shut down the amplifier first, let the sound collapse, and then shut down the source.
Such as i do.

Am I right in thinking I can just use one resistor across the leads going to the amp.

yes.

[Redshift187]

If you don't plan on changing the voltage, calculate the resistance that would give you 1W (or a little less) of dissipation and use a 3W resistor. That way you have a good value for the bleeder, and you have some safety margin on the resistor wattage.

[Redshift187]

The other thing I made for dealing with possibly charged capacitors is a 10W 5R resistor in a small case with insulated leads terminated with insulated alligator clips and a switch completing the circuit. Connect, switch on and the capacitors are discharged.