Mosfet Powered Solenoids: Configuration Question

Other Hardware General Electronics
1

I am trying to power an array of solenoids at differing intensities. My circuit worked just fine on the breadboard (circuit A in illustration). When I etched the board, I changed it to circuit B (or circuit C if the solenoid is reversed), because I didn't think it would make a difference. It made the wiring simpler.

Now, my etched circuit (B or C) isn't working and I'm not sure why. Is it due to the new wiring? Also, there is a possibility that ALL of my IRFZ40 N-Chanel Power Mosfets are broken (wish I had tested them first). Anybody have any ideas on this?

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2

The IRFZ40 is not a "logic level" MOSFET. It will not turn on (fully) with only 5V applied to its gate terminal. I'm surprised that Circuit A worked for you. Did you try it with 5V at the gate? Are you sure you were using IRFZ40's?

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I can't help with your question, but I did like your illustrations. I've never seen that type before. How did you make them?

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Thanks for the troubleshooting tip, RuggedCircuits. I duplicated the above circuits on breadboard to play around with triggering the mosfets by a test straight+5V.... only to stumble across a silly mistake I made (of course). The 470 ohm resistors I purchased from All Electronics turned out to be 470K ohm (big difference). They were miss-packaged and I neglected to inspect them carefully (they were color-coded properly).

Anyway, If anyone wants to control some fairly strong solenoids (with varying intensity) via variable pwm, all of the circuits above work like a charm. You're gonna need a lot more wattage from your power source than you might think, though. I'm pulsing enough solenoids ( 8 ) often enough to play a drum set at a quick pace & I ended up needing at least 600w at 24V to get the job done.

.......

Daanii - I made these illustrations in Adobe Illustrator. I set up a perfboard grid and make little models of the components I'm using at-size. Then I can more manually design my circuits. I'm a graphic designer, so I'm more comfortable with that program and might be a bit more obsessed with the final aesthetics of the circuit boards.

The only hitch is that most etching services don't accept pdfs (as the file type) for each side of board to be etched. I found a place in England called P+M Services that accepts pdfs & they did an amazing job for me. I just manually put little dots to indicate where I needed holes and they were able to accommodate that: