I've reviewed many questions on the list, but still having difficulty driving my Fotek SSR-25 DA Solid State Relay (Spec Sheet - http://www.fotek.com.hk/solid/SSR-1.htm) from my Raspberry Pi.
Here's my circuit:
GPIO 26 -------1kR -----+ | +------------+ | | | -- + +--+ = Fan SSR | -- - ---+ = 120v | | | | +------------+ GND --------------------+
Here's what I know:
- Circuit works fine when input cycled from +5v to 0v with another controller (Labjack).
- Circuit causes fan motor to buzz when hooked up as shown (never turns on).
- Tested input switched between Pi's power rails +3.3v to 0v. Same behavior.
Here's what I suspect:
- +3.3v is not enough to drive my specific SSR (although specs would indicate it should), or,
- Pi not supplying enough current by GPIO26 to fully trip SSR.
- Any tests recommended?
- How do you adjust current output on a GPIO pin (I'm using Python and it's associated libraries)?
- Would reversing the logic provide better switching (e.g. Wire SSR+ to 3.3v and switching SSR- between 0.0v and 3.3v)?