please dont rip this site

Hardware Peripheral Input/Output

Motor Over-Current detection / protection

Classic overcurrent detection scheme.

by Michael Rigby-Jones [mrjones@NORTELNETWORKS.COM]

                R
From 12v _____/\/\/\____________ To motor
           |__              |
              \>|           |
                |--/\/\/\---+
               /|    4k7
              |
              |

            To PIC (needs dropping to 5v for PIC)

The transistor is a PNP device. Resistor R is chosen so that at the current you want to detect, the voltage drop across it is enough to switch on the transistor, say about 0.6 volts. The other resistor is to limit the current through the base/emitter junction.

So for 10 Amps this would give 0.6/10 =0.06 ohms. Not a very easilly obtainable value! But to achieve this kind of resistance you can experiment with a small coil of copper wire, you won't need much. Some commercial designs use a PCB track as the curent sense resistor.

Note that is circuit is not a precision design, the current at which it activates will vary a bit with temperature etc, but it should be OK just for detecting a stalling motor.

See also:


file: /Techref/io/motor/overcurrent.htm, 1KB, , updated: 2006/11/3 10:03, local time: 2024/12/7 07:30,
TOP NEW HELP FIND: 
18.97.14.82:LOG IN

 ©2024 These pages are served without commercial sponsorship. (No popup ads, etc...).Bandwidth abuse increases hosting cost forcing sponsorship or shutdown. This server aggressively defends against automated copying for any reason including offline viewing, duplication, etc... Please respect this requirement and DO NOT RIP THIS SITE. Questions?
Please DO link to this page! Digg it! / MAKE!

<A HREF="http://www.piclist.com/Techref/io/motor/overcurrent.htm"> Hardware Peripheral Input/Output </A>

After you find an appropriate page, you are invited to your to this massmind site! (posts will be visible only to you before review) Just type a nice message (short messages are blocked as spam) in the box and press the Post button. (HTML welcomed, but not the <A tag: Instead, use the link box to link to another page. A tutorial is available Members can login to post directly, become page editors, and be credited for their posts.


Link? Put it here: 
if you want a response, please enter your email address: 
Attn spammers: All posts are reviewed before being made visible to anyone other than the poster.
Did you find what you needed?

  PICList 2024 contributors:
o List host: MIT, Site host massmind.org, Top posters @none found
- Page Editors: James Newton, David Cary, and YOU!
* Roman Black of Black Robotics donates from sales of Linistep stepper controller kits.
* Ashley Roll of Digital Nemesis donates from sales of RCL-1 RS232 to TTL converters.
* Monthly Subscribers: Gregg Rew. on-going support is MOST appreciated!
* Contributors: Richard Seriani, Sr.
 

Welcome to www.piclist.com!

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  .