Bleeder resistor action

[sam9]

Breeder resistor action

Anyone have an opinion about how long bleeder resistors should take to drain the caps in a power supply? In terms of them being a saftey feature, I've assumed 1-2 minutes is about right since it would take at least that long to open the enclosure. I don't want it be so short that I'm wasting current, either.

I don't think it needs the be fool-proof since I expect to be the only fool opening the amp

 

[sam9]

I mean bleeder not breeder!!

Yeesh!

 

[faustian bargin]

darn. i thought it was some advancement in biotechnology. self-replicating components, or something.

 

[Circlotron]

I thought it migh be a resistor of oriential origin.

 

[karma]

lol for me when i work on em.i use a old 120watt safety light and
discharge it i dont trust any bleeder resister. i likelly will be told it's not the right way to do it but it works


warning high voltages dont find out the hard way like i did trusting a resister !!hoohaaahollymonky

 

[peranders]

This is a typical trade off.

Short time = Heat.

I should think a time between 5-30 seconds is normal. You could also have an active solution with a transistor or relay + resistor.

 

[sam9]

Thanks Peranders, more the response I was looking for.

Although it's my own fault I got the other responses, being a clumbsy typist.

 

[audiofan]

Be carefull if you are using inductive filter ( choke ) there is a minimum current needed to maintain magnetic flux in core to make shure inductor is making filtering action

 

[jackinnj]

bleeders are discussed in the ARRL handbook -- and the discharge time should be short, like 90% within a second or so. the formula for discharge is

E(sub t)/E(initial) = e^(-t/RC)