Power supply

I was just wondering where to find a power supply between 6v or 9v. I have looked everywhere. Also might a computer psu be able to facilitate this need?

Indrick: I was just wondering where to find a power supply between 6v or 9v. I have looked everywhere. Also might a computer psu be able to facilitate this need?

Only in a universe where 3, 5 and 12 are between 6 and 9.... :P

12-5 is 7 though. You can use the old fan under voltage method to get seven volts out of a PC PSU.

Indrick: I was just wondering where to find a power supply between 6v or 9v. I have looked everywhere. Also might a computer psu be able to facilitate this need?

Have you looked for a "universal power supply"?

What are you looking to power BTW?

12-5 is 7 though. You can use the old fan under voltage method to get seven volts out of a PC PSU.

Given two like rated power supplies , one 12V , the other 5V , if you wire them in series with the 5V subtracting, you will get 7V. (that means the NEG output of the series connection is the POS wire from the 5V supply. )

What current value do you want? What size of supply physically to do prefer? And how much tolerance in your supply is acceptable (voltage regulation, ripple, etc.) 6-9 wall pack are every where for usage if they meet your needs. Old computer supplies are 5 and 12 but can be regulated down. Variable lab supplies can meet the whole range from 6-9V

Any of these can be found through web sales. Also can find these in thrift store, bargain stores, electronics stores. Or build your own (9-12V transformer, bridge rectifier, filter cap, regulator).

wildbill: 12-5 is 7 though. You can use the old fan under voltage method to get seven volts out of a PC PSU.

That only works if there is a load on 5V, -and- not with all power supplies. I replaced my computer PS, and now it won't start if there is a fan wired from 12V to 5V.

If you have the 12V supply why mix the -5V into it. Keep the 5V separate for the 5V needs if any and use a DC-DC converter like this one http://www.ebay.com/itm/DC-DC-3A-Buck-Converter-Adjustable-Step-Down-Power-Supply-Module-LM2596S-/181559857724?pt=LH_DefaultDomain_0&hash=item2a45cf923c

or a TO-220 3 leg regulator like this one http://www.ebay.com/itm/10pcs-L7809-7809-Voltage-Regulator-9V-1-5A-TO-220-New-GOOD-QUALITY-/201161330913?pt=LH_DefaultDomain_0&hash=item2ed62650e1

These can be found from most major parts suppliers local and net.

Why? Because it is quick, easy, and requires no parts. When it works.

If you have the 12V supply why mix the -5V into it.

Why? Because it is quick, easy, and requires no parts. When it works

Amen.

Just for the record, it isn't a -5V supply. All of the wallwarts are two lead devices. two in , two out, meaning they are floating, meaning there is no +5 or -5. It's whatever you wire it to be. If by "-5" you mean the +5V wired in series to subtract then that's what I meant.

I was replying to this:

12-5 is 7 though. You can use the old fan under voltage method to get seven volts out of a PC PSU.

Hum, I missed the specs for quick and easy. BUt again I have both the buck converter and the TO220 regulator on hand so it is quick and easy.

The specs for quick and easy, in this case, is moving the ground wire of a 12V fan from ground to the 5V connector. If the fan in question is one that has a daisy chain 4 pin plug from the hard drive power connector.

A PSU is "humongus" by arduino standards. I personally would much rather use a petite dc-to-dc converter than a huge "brick" like a PSU, but that't just me. My bench is so cluttered I can't spare the Real Estate.

I agree, but someone mentioned it.

Guys, is it possible to power the Arduino UNO with both the USB port and the DC power plug (at 12V)? I wondering if I could power my motor drive with 12V through Arduino pins at the same time I keep Arduino plugged in the computer via USB. Thanks.

No. The USB +5V is automatically switched off by FET T1 (see schematic) when the COMPARATOR U5 detects more than 3.3V on the EXT dc power jack (VIN).