Can I use this power supply?

[EightBySix]

Bit of a noob electronics question. I read about how you can hack a PC power supply to make a cheap electonics bench power supply. Saw that there is a -12V and a +12V output and thought I could use it to run an actuator I have that needs 24V.

The rating on the PSU label says it will supply 8A for the +12V, but my actuator says "Power Rate 24V / Max 4.6 Amp" on the label.

Here is the PSU label:


Will I blow my actuator if I connect it to the yellow and blue leads, or is 8A the maximum it CAN deliver, rather than what it WILL deliver?
Can someone explain it to me?

[boardjunkie]

Nope. 300ma on the neg 12. You could run a Defender board off it, but not a 24v soleniod. Its generally a bad idea to reference from a pos line to a neg line anyway. Plus, without a min load on the 5v line the supply won't even start up. Just get a 24v laptop pwr supply and be done with it.

http://www.ebay.com/itm/24V-DC-AC-power-adapter-HP-ScanJet-5550C-scanner-/300486501865?pt=LH_DefaultDomain_0&hash=item45f66425e9

[lilshawn]

agreed, you are limited by the weaker of the 2 rails.... in this case, 0.3 amps.

agreed, without a proper load on the 5V line the voltage on the rest of the rails will be way off too.

but you might get away with running your actuator off 12 volts. not sure what kind of actuator you have there but, agreed a 24 volt power supply is pretty easy to come by nowadays.

[EightBySix]

Just get a 24v laptop pwr supply and be done with it.

Ok - good advice. I ended up with a universal laptop psu from ebay that looked quite good - it has a 5v usb output too which should be useful.

I was expecting some sort of selector switch - but instead it has a system of various tips that attach to the laptop - each designed for a diff model of laptop, and each delivering a diff voltage.

the tips plug onto a little terminal block with 8 pins, so the voltage must be made up from a combination of pins. I tested every combination of pins with my meter and coould get a max of 16v, although I have verified that one of the tips when plugged in gets 20v. Is it adding up the voltages on the connector block?



I'm about to take my dremmel cutter to the 20v tip to see how it works, but thought I would pause and ask if anyone has a more scientific way of figuring it out...