Rasberry Pi GPIO pins not switching

General
21

This relays don't work with RPI, because the gpio output is too weak to drive the inputs of relays. For 1-3 pins works, but if you connect more, the output driver of RPI is out of valid range.
The solution is to use a very cheap driver IC. If you want, I can share the wiring diagram here.

22

I think the issue is that the sainsmart 12volt relay requires its own 12 power rail.
No dirver chips are needed as this is included on the relay board.

23

If you look at sainsmart website:

SPECIFICATION:
  • 12V 16-Channel Relay interface board, and each one needs 15-20mA Driver Current

How is this possible with max. 16mA on each pin and max. 50mA rail current on 3.3V?
16x15mA=240mA
:nauseated_face: -> Raspberry Pi

24

I'm sure it would help!

25

12Volt power doesn't come from Rpi - only logic level to trigger the relays via transitors onboard.