Power supply rating

[Tom Sanders]

Hello,

I have a power supply rated at 500V dc and 0.5A. I am using this with
two 10 Megaohm 0.25W in series to charge a capacitor of 10pF. Because
of the two resistors in series, the current in the circuit would be
0.25 uA. What does the current rating on the power supply mean? Is
that given for safety reasons?

Please help.

THanks,

Tom

 

[Tim Wescott]

Hello,

I have a power supply rated at 500V dc and 0.5A. I am using this with
two 10 Megaohm 0.25W in series to charge a capacitor of 10pF. Because
of the two resistors in series, the current in the circuit would be
0.25 uA. What does the current rating on the power supply mean? Is
that given for safety reasons?

Please help.

THanks,

Tom

Go above the current rating and either the power supply will destroy itself
or (hopefully) blow a fuse or go nicely into current limit, depending on its
design.

You have a whopping big monster of a power supply to do a job that could be
done with a dry cell and a vibrator!

 

[Spehro Pefhany]

Hello,

I have a power supply rated at 500V dc and 0.5A. I am using this with
two 10 Megaohm 0.25W in series to charge a capacitor of 10pF. Because
of the two resistors in series, the current in the circuit would be
0.25 uA. What does the current rating on the power supply mean?

It means you should get someone else to do whatever it is you are
fooling with.

Is that given for safety reasons?

Yes.

Best regards,
Spehro Pefhany

 

[Spehro Pefhany]

Go above the current rating and either the power supply will destroy itself
or (hopefully) blow a fuse or go nicely into current limit, depending on its
design.

You have a whopping big monster of a power supply to do a job that could be
done with a dry cell and a vibrator!

Where would he put the dry cell?

Best regards,
Spehro Pefhany

 

[Tim Wescott]

Where would he put the dry cell?

Must. Resist. Potty. Joke...

Sorry -- Dry cell, vibrator and _diode_, to make a simple flyback circuit.
Point being he's using a 250W power supply to deliver an instantanious power
of 25mW. Unless there's high winds and he's worried about the capacitor
blowing away he's using way more power supply than he needs.

Best regards,
Spehro Pefhany

http://www.speff.com

 

[Paul Hovnanian P.E.]

Must. Resist. Potty. Joke...

I think its an 'embedded systems' joke.

Sorry -- Dry cell, vibrator and _diode_, to make a simple flyback circuit.
Point being he's using a 250W power supply to deliver an instantanious power
of 25mW. Unless there's high winds and he's worried about the capacitor
blowing away he's using way more power supply than he needs.

This might be something he's rigging up in the lab. Maybe that's the
smallest 500V supply he has handy.

But if he has to ask this simple a question, I'd suggest he not mess
around with 500 volts.
Or at least do so with someone with experience looking over the wiring
before he throws the switch.

 

[Mr Hard Man Gay]

Go above the current rating and either the power supply will destroy itself
or (hopefully) blow a fuse or go nicely into current limit, depending on its
design.

You have a whopping big monster of a power supply to do a job that could be
done with a dry cell and a vibrator!

God.... you're so smunggely. Next thing you'll be telling us how to program
a 350milliongigaburp processor to do the job in 'real time'.

Ta