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View Full Version : pic: VEX power from 12v

Andy Brockway
02-04-2012, 09:46
[cdm-description=photo]25975[/cdm-description]
djshaffer
02-04-2012, 09:48
im woundering what resistors you had used in this project, my team is wanting to do the same thing, Thanks!
StevenB
02-04-2012, 10:06
Whoa, way to revive an old thread!

The key part is a variable voltage regulator (probably an LM317T (http://www.radioshack.com/product/index.jsp?productId=2062601)), so take a look at the datasheet (http://octopart.com/partsearch#search/requestData&q=lm317t) to find out exactly what resistors you need. The Vex controller needs between 7.2 and 9V. You could also use a straight 9V voltage regulator (http://octopart.com/partsearch#search/requestData&q=9V%20voltage%20regulator), although you would probably have to order these instead of getting them from Radio Shack.
JosephC
02-04-2012, 13:23
Plug it into your Digital Sidecar, that's all we did.
Alan Anderson
02-04-2012, 14:36
Plug it into your Digital Sidecar, that's all we did.

There were no Digital Sidecars in 2006.
AlexH
02-04-2012, 17:51
the vextrollers do work at 12v. just have to be careful with the amp draw at the higher voltage.
DonRotolo
02-04-2012, 19:54
The LM317T also really prefers a heat sink for anything more than about 1/2 Amp, and a large capacitor (~10 uF) at the output will help it as well. Again the datasheet is your friend.
Steven Sigley
05-05-2012, 02:40
I made one of these based on the information in this thread and a data sheet from I believe it was TI. I've drawn up a rough sketch of what the circuit looks like and figured I'd share it. Works great for us and outputs 7.2 Volts, just about what the Vex computer would love to have.
Here's the rough schematic I made:
http://s7.postimage.org/8v269gm4p/20120504_181754.jpg
Steven Sigley
05-05-2012, 02:53
The LM317T also really prefers a heat sink for anything more than about 1/2 Amp, and a large capacitor (~10 uF) at the output will help it as well. Again the datasheet is your friend.

http://www.vexrobotics.com/products/accessories/logic/276-2170.html

At least on the old computer it says that with motors and servos the computer should draw about 62 mA. I have a heatsink on the LM317 on the converter I made but after testing it and reading this bit of information, i think it may be unnecessary.