PDA

View Full Version : Homework Board Relay Control? Or other Method?



divzr0
05-21-2006, 12:21 PM
Hey guys

I have had the Homework board for some time and I have been thinking about using it for a project.

I would like to utilize the stamp to switch a relay. I'm thinking of having the relay control a model rocket ignitor, or (4th of july is coming) other pyrotechnics. In my testing the board cannot source enough current to switch a 5V low signal relay which controls a 12VDC battery supply. I looked at a relay supplied by parallax for industrial control but it was 10 dollars a pop. I was thinking of making a 12 channel setup, at that price it would be well out of range.

I have two questions...

1. Is there an alternative way to switch this 12V supply on?

2. If I had to use a relay in another project like for turning on 110AC, how can I provide the appropriate current?

Thanks!!!


Chris Savage
05-21-2006, 12:58 PM
Hello,

Attached is an example of controlling a relay using a Stamp I/O pin. Now, if you have the correct power transistor then you could eliminate the relay altogether. As for your second question you would need a solid state relay. Please see the following links.

http://www.parallax.com/detail.asp?product_id=31204

http://www.parallax.com/detail.asp?product_id=400-00010

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Chris Savage
Parallax Tech Support
csavage@parallax.com (mailto:csavage@parallax.com)

divzr0
05-22-2006, 05:51 AM
Thanks Chris. Any suggestion on what kind of power transistor, or maybe a quick and dirty on how to choose the right power transistor? This part is new to me. Thanks.

Chris Savage
05-22-2006, 06:04 AM
It's all in the details. You would need to know how much current (max) these ignitors use to choose the correct part to drive them. Also, how many volts they require.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Chris Savage
Parallax Tech Support
csavage@parallax.com (mailto:csavage@parallax.com)