NerdKits - electronics education for a digital generation

You are not logged in. [log in]

NEW: Learning electronics? Ask your questions on the new Electronics Questions & Answers site hosted by CircuitLab.

Basic Electronics » Power Supplies

October 26, 2010
by Ethanal
Ethanal's Avatar

I am getting tired of my 9v battery running out and I am looking to upgrade to a power supply like this one with this board. I am really paranoid about high voltages/currents and using things that plug into the wall for a non-standard use, so I was wondering if a computer power supply can output voltage/current high enough to harm a human?

October 26, 2010
by rajabalu21
rajabalu21's Avatar

I personally think that it is a overkill. A simple wall adapter would be sufficient for your experimental needs.

-Raja

October 26, 2010
by Rick_S
Rick_S's Avatar

This power supply is one I purchased and works great for breadboarding. They're sold on ebay (Link for one).

You can see one mounted on the board I was testing the Wii Nunchuck on in the photo below.

The PC power supply I would have to agree with Raja, would be serious overkill.

Rick

October 26, 2010
by mongo
mongo's Avatar

I have to agree... The PC power supply has all the power you might ever need for lots of projects but it is certainly serious overkill for these little kits. I'd stick with the wall warts. The cell phone charges that plug into the USB connectors of the phones are usually a pretty well regulated 5V power supply and easily adapted to these kits. Just make sure it is a regulated one, or you can continue using the regulator that came with the kit.

October 26, 2010
by Ethanal
Ethanal's Avatar

I was going to use it to power stepper motors also, but I guess I could use a separate wall wart for that too.

December 14, 2010
by danuke
danuke's Avatar

I had mentioned this on an other discussion, but I was googling around and found some listings for Powered Breadboards. They look really nice. One 5V and two variable 15 (- & +) V supplies.

http://www.mpja.com/prodinfo.asp?number=17710+TE http://www.circuitspecialists.com/prod.itml/icOid/9651

some have meters on board others do not (makes them cheaper)

April 13, 2011
by BobBolinger
BobBolinger's Avatar

If I buy a wall wart power supply like this from sparkfun, and snip the end off, how do I know which lead is which when I fasten them into the battery-plugin-part of the breadboard?

April 14, 2011
by Rick_S
Rick_S's Avatar

The best way would be to check it with a multimeter. If you don't have one (which I would recommend getting one), an alternative would be to use an LED with a 1k resistor in series. Connect your power from the adapter to your circuit. If the LED lights, then the wire connected to the Anode of the LED is positive and the one to the cathode is negative. If it doesn't light, then they are backward and you can double check by reversing them. A simple LED circuit like described makes an easy to build polarity checker.

Rick

April 14, 2011
by Hexorg
Hexorg's Avatar

I don't know, a lot of you guys say that PC power supply is an overkill, but I think I'd rather go with a PC then a wall plug. Because of the price.

I bought a used 150W power supply from a local computer parts store for $7! It outputs +5, +3.3, +12, and -12 volts. Inside of it there are also a short-circuit breakers, that will turn power off if the short circuit is detected.

Cheapest wall plug I could find was $20 in radio-shack, and (of course) it didn't have the short-circuit detector. Wal-mart's cell phone chargers are starting at $12, but they usually provide 1A of current max, and I had a few projects that needed 1.2A @ 5V, so the voltage from them would drop.

April 14, 2011
by BobBolinger
BobBolinger's Avatar

Thanks

April 15, 2011
by Keyster
Keyster's Avatar

Here is what i have:

my power supply

i suggest keeping your eyes open while driving down the road. you may find an old computer laying on the side of the road. remember, one man's trash is another man's treasure! ;)

when i first set this up i just left the original wires hanging out the front, tinned the ends and just plugged them right into the breadboards. i cut away the ones i was not going to use and also cut away all but two of each voltage so there was not SO MANY wires hanging around. as you can see i have upgraded it over time, banana clips and LED to show power status. i have another one just like it (similar anyway) out in my garage to charge model airplane batteries.

things to keep in mind!!! when you open this thing there are some LARGE caps in there. be careful!! i am not saying they will shock you but i know caps hold charges so it is always a good thing to be safe and not sorry. also, some power supplies must have a drain to even turn on. this one did not but my other power supply has a 12 volt car break light hanging off of it to always pull power when it is turned on. if memory serves i have the light connected to the 5 volt line so it is dim but it is enough to keep the power supply in the ON state. google around for other ideas of things used to keep power supplies running.

overkill??? yes...

knowing i can run three NerdKits (mesh network), charge a 3000mah lipo battery, and run a handheld GPS all while whistling dixie..... Priceless!!!!

April 15, 2011
by mongo
mongo's Avatar

Welcome to the exclusive re-purposers club!

I have been re-using old junk for years, that others have no use for.

April 15, 2011
by Hexorg
Hexorg's Avatar

You guys haven't seen an overkill, untill you saw this!

April 16, 2011
by Rick_S
Rick_S's Avatar

That is definitely some serious overkill. BigGrin

April 22, 2011
by BobBolinger
BobBolinger's Avatar

Rick S where do you buy those connectors on the ends of the leads that I see in your photos?

April 22, 2011
by Ralphxyz
Ralphxyz's Avatar

BobBolinger, since I asked Rick that same question three months ago I can answer that.

You can get them off ebay, I'll try to remember exactly what they are called.

I just order 50 of them and then ordered a new breadboard and they sent another 50 with the breadboard

so now I have them all over the place.

They really are convenient though they do get rather tangled looking if you are not careful or you use them on more than 3 -4 pins.

Ralph

April 22, 2011
by BobBolinger
BobBolinger's Avatar

thx Ralph, Frys is just up the road from me, I bet they have them...

Post a Reply

Please log in to post a reply.

Did you know that a flyback diode is important when driving a motor or any inductive load? Learn more...