BENCH POWER SUPPLY - Help!

[COACHTJ1688]

I wanted to be able to work with the control system at my home so I recently purchased a radio shack bench power supply model # 22-510.

It ranges from 12-13.8 volts and its 25 amps. It is switched but not variable amperage output.

Will I blow up the RC if I use this for power while testing?

If so, any suggestions on us9ing a switched power supply? Is there any way to rig up a voltage regulator...or an amperage regulator, perhaps a dimmer switch?

I can't find any specs on the battery itself. I don't have one inf rom of me and I'm guessing at model numbers on the mk battery site.

[COACHTJ1688]

Looking deeper into some other posts I've found that the RC has an internal regulator?

Can anyone confirm this?

[HotWings]

Originally Posted by COACHTJ1688

Looking deeper into some other posts I've found that the RC has an internal regulator?

Can anyone confirm this?

You'll be absolutely fine! When you charge the batteries from the Kit, they sometimes go as high as 14.7volts! I am our teams electrical captain, and i permit you to continue with your work

[COACHTJ1688]

I'm worried about amperage. The output is 25 amps.

[HotWings]

Originally Posted by COACHTJ1688

I'm worried about amperage. The output is 25 amps.

Yes i know, It should be fine.. Amps at that level shouldn't really mean anything. And plus like you said i am 99% sure there is a built in regulator in the board. 1 sec though.

[COACHTJ1688]

Thanks for the quick replies. This is my first foray into programming. I'm normally the welding/build guy.

I've seen my share of magic smoke released from electronics...and I'd rather not destroy a brand new RC if I can help it.

[HotWings]

http://www.ifirobotics.com/docs/firs...up-charger.pdf

Theres the wiring diagram. Seems like its there to me

Like the other guy said, its only going to draw the amps it needs.

[DonRotolo]

Electrical circuits only use as much amperage as they need.

Water pressure is like voltage, while water flow rate is like current (Amperes).

If you turn on a faucet, it doesn't matter if the pipe behind it can supply a thousand gallons per second, the faucet will "use" what it uses. If, however, the pressure (voltage) gets too high, the faucet may burst - so keep the voltage below around 14 volts and you'll be fine. 25 Amps is the max, the circuit determines what it "uses".

Note: Switched power supplies need some load to regulate properly. be sure something is connected to it before switching it on. Maybe won't matter, but cheap insurance.

Good luck,
Don

[COACHTJ1688]

I'll keep the receipt handy. HAHA.


Thanks for the help. I'll make sure to report my findings to either this forum, or the fire department...or both.

[yongkimleng]

I'm not sure whats the quality of your PSU, but what I'd do on an unknown PSU (including those for computers):
1. Connect up voltmeter parallel to the 12v rails
2. Add a 12v load: maybe a 12v fan or two.
3. Fuse in series with your 12v line: I think 10A is more than enough?
4. A switch [S1] in series with your 12v line just BEFORE your control systems

So you turn on your psu first, but leave S1 off. Check the voltage and if you're happy, turn on S1. Reason being some switching PSUs start off with a voltage >>> 12V for a few milli/micro seconds immediately after turn-on and may fry your stuff. Just a precaution

[Rickertsen2]

It will be fine. The regulation circuitry is pretty robust. I've seen one of these things take a short spike of about 24v and live happily through the rest of a season. The power supply you mention should keep the RC comfortable.

[popo308]

Originally Posted by COACHTJ1688

I'm worried about amperage. The output is 25 amps.

The O/I can draw a max of 1000ma ((1amp) (i believe)) 25 amps i think is a bit much??

[karlcswanson]

If you just need to power the RC, you might be able to save a few dollars and just use an old 12V wall wort transformer with some female spade connectors crimped on to it. The backup battery might even work when hooked up to the 12V terminals.

[HotWings]

Originally Posted by karlcswanson

The backup battery might even work when hooked up to the 12V terminals.

Not a good idea to me lol.

[Andy A.]

According to IFI's published data, here (.pdf), the typical draw of the RC is between .75 and 1.5 amps, likely very dependent on the radio's draw. So far as I know servos are still powered by the back up battery. Maximum voltage is 15, and minimum is listed as 7, although I've noticed that radio performance degrades quickly as voltage drops below 12. If you operate with a tether then the OI will also be powered by the RC.

The power supply you've got should be capable of running the RC easily. The RC will draw exactly the same current for a given voltage regardless of the supply. However, as others have noted, switching power supplies are not always the cleanest sources, and the high current rating of this supply suggests that it's not intended to power sensitive micro electronics like that in the RC. If possible it would be nice if you could use a 'scope to look at the output and ensure that it is 'clean' and the supply is calibrated. Failing that a multimeter will at least ensure that the voltage it creates is in fact what it says it should be.

Most teams power the RC using one of the supplied batteries while testing. I would recommend doing the same, and using a fast acting fuse or breaker with a 3 to 5 amp rating, regardless of the supply, to safe guard both the RC and the supply. A charged battery should be capable of running the RC for several hours.

-Andy A.