A bit out of my comfort zone. I have a Fotek SSR with 3-vdc - 48-vdc control input.
To test the current required I used a 12-vdc supply and the SSR showed 15.6-mA.
I then rigged up a 12-vdc-buck with the output set to 5-vdc and the SSR showed 11.5-mA.
15.6-mA x 12-v = 0.1872 Watts
11.5-mA x 5-v = 0.0575 Watts.
I don't understand (limited electronics knowledge here) why the Wattages are so different as I thought that the Wattage needed would be a constant and at 5-vdc would require 38-mA.
But, given the measured mA at 5-vdc is well within the rating of a Data Pin (40-mA max), I am thinking of using direct control of the SSR by D6 (or whatever).
I checked the current drain with two different meters so pretty confident it is within 0.1-mA accuracy. I am only using Nanos so no big deal if I break one while testing but I am wondering if it is OK for long term.
The SSR input is an LED with a resistor (both inside the unit).
The current will vary with the supply voltage (more "V_in", more current).
OK connected direct to an I/O pin.
Many fake products out there ... I've found that you may need at least 12VDC before the output reliably triggers on. I'm guessing that the specifications for the relay you've received is crippled.
@Runaway Pancake:
Thanks for the explanation. I have connected it direct and as you suggest, it is working fine.
@Dlloyd:
This one looks like the one with the red "Fotek" in that link. It is a 20A version and I am only using it to switch a 100W 120vac motor, so it's doing fine. I need to pulse the motor and it is currently doing just that with 0.5-second on and 2-seconds off.
Just for fun, I tried using three-AA NiCad batteries and it was switching and holding fine too at 3.6vdc. Guess I got a good one. I did panic for a few seconds when the LED came on, but the motor didn't move, then realized I had not plugged the motor into the Mains.
Can you test this by measuring the current? An SSR basically has an optocoupler inside. If the LED is reasonably on, this should be visible in the current.
ElCaron:
Can you test this by measuring the current?
Sorry, I do not understand. The two measurements in OP above were measured using a DMM and the SSR was working fine as it did at 3.6vdc. I didn't measure current with the NiCads, but the LED was on and the motor ran just fine.
I have now connected the SSR directly to the D6 pin and all good and working fine for 10-hours non-stop, pulsing motor on and off, 0.5-sec on, 1.5-sec off.
Thanks to all, the help and explanations are very much appreciated.
