Help using a solid state Crydom IA5 Relay

Thread Starter


Joined Jan 13, 2018
I am working on a Raspberry Pi Magic Mirror project, and need my Raspberry Pi to cost effectively detect a Z-Wave signal. I have a $16 Z-wave wall module that switches 120VAC on/off. I intend to wire that module to a relay using 120VAC as the control signal to toggle a low voltage signal. This low level signal will be detected by my Raspberry Pi.

I am experimenting with that relay now. Is is a Crydom IAC5 (spec sheet attached). I have wired as follows (picture attached):
  • 120VAC wired to pins 1 and 2
  • 5 VDC power supply wired to pin 3 (+5 VDC) and pin 5 (ground)
  • Voltmeter wired to pins 4 and 5
However the voltmeter on pins 4 and 5 not show any DC voltage. Same result if I turn off the 120VAC.

Have I wired this incorrectly, or is it possible I have a defective unit?

Thank you,



Joined Jul 18, 2013
The Opto modules as shown in your jpg schematic of the module is a AC input module and detects a AC input voltage, the output is a open collector output, you need to supply a collector load and voltage.
The boards made by Opto etc have all the interfacing needed.


Joined Mar 14, 2008
As Les noted, the output is a switch.
You need to add a resistor from the 5V supply to pin 4 as shown below from the relay data sheet:


Joined Jul 18, 2013
You can obtain the Opto22 interface boards on ebay etc, these have a status indicator, fuse and I/O terminals etc.
Pin 4 needs the pull up resistor to 5v.
I have quite a few, Cheap if needed!;)