[Here is a] really super-cheap 5V relay driver. It uses an emitter follower so it actually delivers only 4.4V or so to the relay but this has always worked fine for the 5V relays I have used. It does not require a protection diode because the emitter follower won't allow any undershoot.
Use a 2N3904 transistor for up to 100mA. A 2N2222 may be used for up to 200mA. A ZTX689B is good for up to 500mA.
This circuit will NOT work with the open collector outputs on a PC Parallel Port, but will work nicely with a PIC or other fully driven output capable of sourcing a few milliamps.
- Lowest parts count
- Lowest cost
- Only good for driven outputs (not OC) and relays that will pull in at 4V
|file: /Techref/io/relay/smallLV.htm, 1KB, , updated: 2009/1/26 15:06, local time: 2018/8/15 08:04,
|©2018 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?|
<A HREF="http://www.piclist.com/techref/io/relay/smallLV.htm"> Relay driver, Solenoid driver, low voltage relay, low voltage solenoid, relay | solenoid IO</A>
|Did you find what you needed?|
PICList 2018 contributors:
o List host: MIT, Site host massmind.org, Top posters @20180815 RussellMc, Van Horn, David, Sean Breheny, David C Brown, Isaac M. Bavaresco, Bob Blick, Neil, John Gardner, Denny Esterline, Brent Brown,
* 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!