Trouble with 5 voltdc to 110ac relay on a homeworkboard
Hi,· I am a newbe to the stamp world but would like to controll a 110 ac light with the bs2. I have a homework board and have done most of the projects but would like to make the leap to controlling a 110 load. I bought a 5v dc to 120 mechanical relay and can get the coil to set using a 4.5 volt dc external supply but can not get it to set using the high pin of the stamp. I have tried using the npn transistor that came with the stamp but don't understand why I am getting 3.8 volts when the base is LOW and less when the base is high ( although the led lights up). I then tried to use the Vin to Vss connection, this worked and would set the coil but all the time, I could not release it, the voltage never dropped below 8 volts (even with the pin set to low). I would very much apreciate it if somebody could help me on this one. If there is a recomended brand name or modle or If I should go with solid state please let me know. I know a bit about electronics so don't worry about tech talk.
Comments
I use the Crydom SDV2415 for a lot of my applications depending on the load.
I am sure someone else will chime in but as I recall, the homework board is somewhat limited due to battery power only.
Post Edited (Eric R) : 9/24/2006 3:27:52 AM GMT
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Have Fun
TR
Post Edited (TechnoRobbo) : 9/24/2006 3:27:02 PM GMT
Thanks
Search Parallax for item: 27945 and use the mating G4 board as this would be a safer·way of doing this. After all, the work is done for you. Just hook up the wires.
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If you relay want to protect your Stamp try this circuit. It completely isolates the stamp from the relay voltage. 4N35 optocouplers go for about 30 cents each.
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Have Fun
TR
Post Edited (TechnoRobbo) : 9/24/2006 10:06:34 PM GMT
I will rebuild it with the opticoupler to isolate it and start my projects. Thanks again to Tr and Eric.
Thanks
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Have Fun
TR
Post Edited (TechnoRobbo) : 9/26/2006 11:28:54 PM GMT
Snap
Thanks to the blokes who helped me tie the ground togeather.