You might remember Mau and his Flush-O-Matic that I wrote about a while back. He sent me his latest work called the ReleShield. It’s a relay shield for the Arduino that allows you to control high voltage appliances. No word on kits yet.
This is a prototype for use Arduino protoshield and a few other components, the purpose is simple but very useful. Ever wanted to control the lights from your home computer? Or perhaps some other appliance in the house.
More about the ReleShield
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10 thoughts on “ReleShield for Arduino”
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A relay board for the Arduino is a really useful project. I don’t think we’ll see kits any time soon since it’s built on a protoboard (not to detract from it in any way, but it’s hard to sell a kit and ask buyers to use a protoboard).
One thing to note though, from the schematic, the relay coils are being driven directly off the Arduino IO pins. I’m kind of surprised the Arduino can output enough current to drive the relay at all, but even given that it can, when electomagnetic fields collapse, they send a high voltage spike back out. This will fry the IO line on the controller. At the very least there should be a diode to protect the controller, and ideally there should be an optoisolator.
The Oracle,
Thanks for the insight! I will forward your suggestions to him. I know he will be offering a kit soon, but maybe there are a few revisions he should consider first….Thanks again!
This looks really dangerous and could damage your microcontroller. _Always_ add flyback diodes (use schottky-diodes for this) to the coils of relays or motors. There are even relays with build-in diodes.
Besides the Arduino can only supply 20mA on it’s i/o-pins, there are relays that are satisfied with that, but most relays aren’t, so please put at least a transistor or better: darlington-transistor in front of it.
Another possibility for switching high voltages are solid-state-relays. No moving parts, faster and they can be connected like an ordinary LED (they just include IR-LEDs). They even come in secure housings, with screwed contacts and covers on the high-voltage-side. Always be careful with high voltages!
Thank you very much to Oracle and Chris, this is just a prototype, but i will improve it until it come safe for all. In the while i’ll do an update on my post to warn everyone that it is dangerous to use in that way. Sorry if i put somebody in danger and their Arduinos. Thank you again and i’ll be in touch.
Thank you very much to Oracle and Chris, this is just a prototype, but i will improve it until it come safe for all. In the while i will do an update on my post to warn everyone that it is dangerous to use in that way. Sorry if I put somebody in danger and their Arduinos. Thank you again and i’ll be in touch.