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Not sure how you have everything set up, but also beware that arduino voltage regulators are typically pretty 'weak' - they may only regulate a few hundred milliamps, of which the arduino may take a hundred or more. If you're only running another logic circuit or a few LEDs, this is typically fine. But trying to run something taking actual current/power...your relay coil, large lights/LEDs, anything containing a motor, etc through the arduino voltage regulator - this will pretty quickly kill the regulator on the arduino and may pass 12V power straight through ...or blow the chip off the board completely. (Don't ask me how I know - lol :))

Also be careful if you have your relay wired on the same power rail with any of the sensitive 'logic' style boards... arduino, MP3, etc. When the relay opens/closes, you can get a voltage spike/inductive kickback out of the coil which can spike hundreds or even thousands of volts on the line. If this is the case, it would be ideal to have a 'freewheeling diode' and/or other snubber set up on the coil.
I agree and in fact you must use the diode if you’re using solenoid, there is instructions on the buttonbanger website. Also, it’s always a good idea to separate the power supply from lights and solenoids from your controller.
 

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Discussion Starter · #22 ·
Not sure how you have everything set up, but also beware that arduino voltage regulators are typically pretty 'weak' - they may only regulate a few hundred milliamps, of which the arduino may take a hundred or more. If you're only running another logic circuit or a few LEDs, this is typically fine. But trying to run something taking actual current/power...your relay coil, large lights/LEDs, anything containing a motor, etc through the arduino voltage regulator - this will pretty quickly kill the regulator on the arduino and may pass 12V power straight through ...or blow the chip off the board completely. (Don't ask me how I know - lol :))

Also be careful if you have your relay wired on the same power rail with any of the sensitive 'logic' style boards... arduino, MP3, etc. When the relay opens/closes, you can get a voltage spike/inductive kickback out of the coil which can spike hundreds or even thousands of volts on the line. If this is the case, it would be ideal to have a 'freewheeling diode' and/or other snubber set up on the coil.
Thanks for the advice.
the Uno only runs the the 4 channel relay, PIR and the sound chip. But the relay output and the Arduino input are comming off the same 12 VDC power supply. I had a few setups like that before and they lasted alright. It‘s only that I had this sound issue once last year and this last time and I always powered the Unos with 5 VDC. 12 VDC seems to solve the sound issue now but all my setups before always ran on the same 12 VDC power block only, that I spliced the supply having one lead go to the relay to be switched on and off for the wiper motor and the other lead going through a step down circuit to be taken down to 5 VDC and then power the Uno. The power supply for running the relay, PIR and the MP3 player then came from the power and ground pins of the Uno.

And this is where the clones screwed me over this time, since both brands of clones I used didn‘t lower the 12 VDC input but instead put them straight through to the 5 VDC output pins and fried the MP3 player.
At the time, when this happened, I only had the PIR and MP3 player hooked up. The relay wasn‘t even connected at all. Guess the manufacturers saved costs and just didn‘t have those components put in at all.
 
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