SSR trouble when using an additional driver board

[rkhanso]

Hello,
I wanted to bump up the signal voltage from the 3.3v of the Raspberry Pi to something a little higher to give some fudge-factor over the SSR minimum input voltage.

I'm using one of the cheap motor-driver boards off ebay, which works perfectly with my 2-channel mechanical relay board. No trouble there.

But when I connect the SSR to the same driver board, it doesn't work. As soon as I connect the SSR to the driver board, the LED on the driver board lights up. When I activate the GPIO in CraftbeerPi, the LED on the driver board gets a tiny bit brighter, but the output of the SSR does not change. Neither does the LED on the SSR come on.

Do I need to connect this SSR differently than the mechanical relay board? I have 5V and GND coming from the Raspberry Pi to both the driver board and the relay board. I have the - terminal of the SSR connected to GND on the Raspberry Pi. The GPIO of the Raspberry Pi is connected to input of channel 3 on the driver board. The + terminal on the SSR connected to channel 3 output on the driver board.

 

[day_trippr]

Good chance that driver module expects 5V signalling - hence the Arduino affinity.
What happens if you connect the driver module input corresponding to your SSR control directly to 5V or GND instead of the 'PI gpio? Does the SSR switch appropriately?

Cheers!

 

[rkhanso]

The driver board works fine with the RaspberryPi 3.3v GPIO outputs when I use the mechanical relay board after it. So it appears to be taking the lower 3.3 DC voltage just fine on those channels. It's only the SSR that has the problem with the driver board.

I was also able to run the stepper motor that came with the board using the RaspberryPi.

Just to verify, I just tried connecting 5V from the Pi output to the input of the driver board and it still did not work.



RaspbPi------Driver Board-------MechRelay------works OK.
......................... |
......................... |
......................... SSR
......................... |
......................... |
No output change (and LED on driver board is always lit)



or: