I bought this ( https://www.amazon.co.uk/MAKEASY-Channels-Expansion-Optocoupler-Raspberry/dp/B07HBYT41Y/ref=sr_1_3?ie=UTF8&qid=1548849825&sr=8-3&keywords=relay+board+12v+16+channel ) relay board. I want to attach 5 electromagnets to it and 5 buttons. I know that I need to attach diodes to the magnet...

More info regarding your electromagnet needed - probably info you don't have! Connecting a diode across the ends of the coil gives the current a path, so that it doesn't die too fast. Normally, it's reverse-biased, so no current flows through it, but when you disconnect the voltage - switch off you...

Thank you for the responses and sorry I didn't answer sooner, I was trying to workout if I could make the magnet or if I needed to build one. I ended up making one. First of all. How big are those magnets. Because this will tell you sort of what voltage they can work on. And how much power they will...

I started a project in which I need to control 3 electromagnets using programming. I am building the magnets myself and I want them to be as powerful as possible, so the higher the voltage the better. What would be the best way to get the highest voltage for those magnets? I was thinking about havin...