Mike's Project Tracker

Multimeters can give false voltage readings if they have a low battery even without the low battery warning. I mounted the components for the voltage regulator for the MOSFET Driver Board in order to test the regulator by itself.  The regulator drops the voltage from the 48V solenoid power supply to between 1.2V to 30V.  The 30V upper limit was set because the D223 optocouplers cannot handle more than 30V so it is pretty important that this works. MOSFET Driver Board with Linear Regulator Mounted The regulator pot was used to set the voltage output to 12V but the 12V started to drift high, just tenths of a volt at a time.  I thought that my regulator just needed to come to steady state as my set resistors were heating up and thereby causing the voltage to drift.  Also, the 48V power supply is one of those cheap ones off eBay or Amazon so I did not trust it very much.  After a few minutes, the voltage was still going up and I tested the voltage supply ...

Optocouplers can be used on the high side without issue. Optocouplers let us isolate two separate power systems.  In the case of my pinball project, I am using a computer PSU to power the logic, lights, and lower voltage items like motors etc; and I am using a somewhat suspect 48V power supply for the solenoids.  To keep these systems separated, I used optocouplers on my mosfet driver board. When designing the board, I was concerned that my transistor like optocouplers would not perform on the high side of the mosfet gate.  You cannot easily use a NPN transitor on the high side (Emitter Load).  You would normally use a PNP transistor.  The test circuit in the data sheet also showed the optocoupler in a low-side (Collector Load) configuration.  Why did I not use a high-side configuration?  Well, say if something went wrong with my optocoupler, I want my mosfets to default to the off position, ie. ground the gate.  With a high-side configurat...