Need simple 1vdc relay circuit

Jan 20, 2010 6 Replies
A

Okay, admittedly I am not that well versed in electronics. I can solder and follow directions well enough to put together some interesting hacks occasionally, but I'm really a greenie when it comes to certain aspects.



I'm trying to find a reasonable way to accomplish turning on and off a device that is powered by about 3.6vdc. The trigger mechanism would be a cell phone's vibration motor's power source (motor disconnected) which outputs somewhere around 1 - 1.3vdc.



I started this project by using a simple relay circuit controlled by a serial port of a computer, but now want to move it to the cellular angle - which gives me much lower power output unless I go with some sort of bluetooth serial adaptor (which I'm working on as well). For now though, if anybody has ideas on a simple scenario for a quick switching relay circuit that would work for this scenario, I'd really appreciate the assistance.



Thanks af


Vote
Twitter Facebook LinkedIn
T

I second this. Don't forget the back EMF diode across the relay.

Tom

Vote
Twitter Facebook LinkedIn
J

Using a basic NPN common emitter mode so that the collector will pull the load to common. The NPN can then pull a higher voltage load like the low side of a relay.. The relay can be supplied with what ever voltage is required up to the rated spec of the NPN.

A 220 Ohm with that voltage drive, should be enough to saturate a common 2N2222 type transistor..

Vote
Twitter Facebook LinkedIn
J

--- If you can stand to lose about 0.3V of that 3.6V into the load: (View in Courier)

Low side driver:

. +3.6 . | . [LOAD] . | . C .1V>--[1K]--B 2N3906 . E . | . GND

High side driver:

. +3.6 . | . +--------+ . | | . [10K] | . | E . +------B 2N3906 . | C . [1K] | . | | . C [LOAD] ..1V>---[10K]---B 2N3906 | . E | . | | . +--------+ . | . | . GND

JF

Vote
Twitter Facebook LinkedIn
J

Oops... NPNs should be 2N3904 and the PNP high side load switch could be driven a little harder: Low side driver: . +3.6 . | . [LOAD] . | . C .1V>--[1K]--B 2N3904 . E . | . GND High side driver: . +3.6 . | . +--------+ . | | . [10K] | . | E . +-[1k]-B 2N3906 . | C . | | . | | . C [LOAD] .1V>---[10K]---B 2N3904 | . E | . | | . +--------+ . | . GND JF
Vote
Twitter Facebook LinkedIn
M

So you're just getting the wires connected to the bomb, then Aunt Emma calls to tell you her Pekingese threw up on the rose-patterned carpet in the parlor. ka-BOOM

Vote
Twitter Facebook LinkedIn
A

Thanks for the advice everyone. I'll see what I can piece together from your recommendations.

And Michael, Aunt Emma has a shitzu, but thanks for the c> Okay, admittedly I am not that well versed in electronics. =A0I can

Vote
Twitter Facebook LinkedIn

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required