View Full Version : Simplicity Would be Great!!

07-23-2011, 06:04 PM
Hello everyone, I am very new to robotics and currently reading and working with the Stamp. This is my question. I know a little about amps, volts, resistors, but I am a mechanical enginneer who needs to know how to take the output of a stamp 5V 20ma and use it as a switch? I have read the Application Cookbooks, but still very confused. Is there not just a simple way to use the output of the stamp, to switch on an independently powered relay, which can be any voltage and can pass large amps? Yes the cookbooks give MOSFET'S and Buffer Circuits, but when it comes down to using them, the specs are a different language and I am really lost on how to use them. Any help would be awsome. My goal is to be able to turn anything on and off with a stamp processer. THANK YOU!!! If it is easier, you can call me anytime, day or night John Cell (219) 928-8378

Mike Green
07-23-2011, 08:17 PM
Nuts and Volts Column #6 (in Volume #1) discusses how to control motors, relays, etc. from a Stamp I/O pin. Here's (http://www.parallax.com/tabid/272/Default.aspx) the index.

07-23-2011, 09:32 PM

Radio Shack has a 5V 20 mA reed relay with Yianie's name on it.


Duane Degn
07-23-2011, 10:09 PM
SparkFun makes this even easier with this board (http://www.sparkfun.com/products/9096).

I looks like they don't have the relays (http://www.sparkfun.com/products/101) in stock right now. I've purchased the same relays from Digi-Key.

I had one of these relays controlling our kitchen oven but the clicking was bothering my wife so I switched the normal relay for a solid state relay. No more clicking.

I personally like the clicking. (I know Erco does too.)

I've had one of the normal relays get stuck in the closed position once. I doubt this happens often but, just so you know, it's a possibility.


07-23-2011, 10:27 PM
I personally like the clicking. (I know Erco does too.)


It ain't clickin', it's DANCIN' to the beat, Dawg! :)

Nothing cheaper/simpler than 1 reed relay and 1 diode!

07-24-2011, 06:45 AM
Thank you for your direction on the information. I was wondering if a mosfet transistor would be used for larger loads? Also, is the input voltage that triggers the on/off response common for most mosfets?
Thank you again.

07-24-2011, 09:25 PM
Suggest you stick with a relay for now. MOSFETs open a whole new can of worms.

07-24-2011, 10:11 PM
Lets open that can of worms. What do I need to know?

07-24-2011, 10:29 PM
Start here: http://forums.parallax.com/showthread.php?132721

07-24-2011, 10:33 PM
Duane, I looked at the page 'relays' and the specs for the coil amp draw and it exceeds 25 ma. Is this the relay you are suggesting?

Duane Degn
07-24-2011, 10:42 PM
The relay I linked to needs a transistor and some other small parts.

I use the schematic on the relay board (http://www.sparkfun.com/products/9096)page when I use those relays.

I have several of those relays in Propeller projects. I had to change some of the resistor values of the schematic when I'm using the Prop.

The schematic should work fine as is with the Stamp.


07-25-2011, 04:39 PM
The RS reed relay linked is a 20 mA unit and can be driven directly, no transistor req'd.

You DID say "Simplicity Would be Great!!" That's as simple as it gets.