edit: please see updated schematic in later post. I removed an Earth ground symbol and added a ground line from the Arduino to the mosfests source.
2nd edit: added 3rd version of schematic to include the switch I actually have on the mains.
A few months ago I knew nothing about circuits, but over the course of building a few different PEMF devices I think I now know just enough to be dangerous.
(A Pulsed Electromagnetic Field device is essentially a signal generator which will switch "high" currents. Mine switch in the 1hz-40hz range. A short video showing the usage of a previous 9v model can be seen here https://vimeo.com/manage/videos/590700327)
My latest model is much more powerful that anything else I've done and I'm unsure if I designed the circuit correctly. I'd appreciate and suggestions or feedback. And if you think it's weird that I'm using so many mosfets, remember that recently I had no idea what I was doing so this kinda evolved naturally from parts I had and knew. Also, the faster switching the better, and I believe the smaller the fet the faster the switching(?).
- 18v 15 amp power supply (rated 24v 15 amps)
- IRLB8721 Mosfets (x7)
- 24awg copper coils (x7)
- a heatsink
IRLB8721 Mosfet specs:
Some other relevant info:
The mosfets will be the only thing that the Nano controls so each will share access to the 200mA total, making it 28.5mA a piece.
The Nano pins will activate via port manipulation so all mosfet gates will open simultaneously.
Each coil has a resistance of 10.3 ohms.
18v / 10.3R = 1.74 amps per coil or 31.4 watts. 1.74 amps * 7 coils = 12.18 amps total.
My main question is: do I need to ground the Nano to the mosfets' source even if they share the same original power supply, and if so do I need a capacitor? I've seen them in certain schematics.
Some more pics!