SSR low voltage on load side

After lots of searching last night, I’m pretty sure I found my issue being low voltage on load side of the SSR. But not 100% sure how to figure the right size resistor n exes to correct issue.

I’m working on a Lumilor project, and my test panel has four letters on it, TEST, that will all be individually controlled to light up, sequence, etc.

Now when I turn everything on the first letter will light up but stay on no matter the sequence. The other 3 letters will function as it’s supposed too.

I know from watching power supply that each letter when lit is using .030ma roughly. And my sainsmart SSR board says current needed .1-2a. The main project this is working towards will actually have each channel running 2 letters at same time on opposite sides of project. So it should come up to .060ma per channel on the final project.

How do I figure the resistor size needed? And will I need a resistor on every channel? I also read where it’s just wired in parallel on the load line out off SSR.

And in the picture I attached, I’m using a regular relay board current since it works with no issues to test coding.

Thank you for any help on the issue.

I am confused when you do not provide a link to a data sheet for your SSR. Most SSR are AC only. DC SSR use a MOSFET driven by a transistor to invert the logic. What do you use the "resistor" for?

8-Channel 5V Solid State Relay Module
Yes, for AC only: 75 to 264V AC (50/60Hz), Load current: 0.1 to 2 AMP AC

I could only add one picture in original post. Sho here it is!

So, you are switching AC. Still a schematic showing your resistors would be nice and helpful.

I don’t have any resistors. That’s what I’m asking what I need. To bring the load side voltage up high enough for the SSR to turn on and off correctly.

The load side turns off when you are switching AC!!!!!!!

Here is one of the articles I found last night. First topic and figure 1

[SSR Does Not Operate Normally under a Small Load Current]

A resistor for the relay?

I don't think you need one. Most (but not all) SSRs have an internal resistor for the LED.

There also seems to be some driver circuitry on the board. Or maybe that's just to drive the LED. Most SSRs don't need a driver either.

I'd guess that green thru-hole part is a fuse but it could be a minimum-load resistor for the relay. Most SSRs have some leakage and they won't turn completely off without a load (or with a low-current load). Well... It's still isn't completely off but the leakage current goes through the load resistor so almost no voltage appears across the load.

Just posted a link to one article I found last night. Maybe that helps deceive better my issue. First reply and figure 1

Hi,
How about you post a complete schematic (even freehand) of your project using SSR.

Here it is all hooked up and running. As you can see the letter “T” stays on and won’t go off. Then sometimes other letters act sporadicly.

Looks like you're using an inverter.

From this Omron SSR reference page C-344:

Solid State Relays Common Precautions: 8. Inverter Load: Do not use an inverter-controlled power supply as the load power supply for the SSR. Inverter-controlled waveforms become rectangular, so the dV/dt ratio is extremely large and the SSR may fail to release.

1 Like

Thank you!! But it still makes me wonder if not a way.

Somehow others are getting to work. It works perfect with regular relay board. Just don’t want the clicking

A pure sine wave inverter's output signal would be compatible with SSRs.

1 Like

The SSRs need some minimum load,
@johngtaxi needs a 'ballast resistor', a parasitic load,
since, apparently, his intended load is not pulling enough current.

So I need to research those items/ terms and see how the install on the load side?

Or is there a specific type of SSR that I can search for that works with inverter?

What's the rating of this 'inverter'?

Someone cited 100ma minimum for the SSRs. That would be a 12w each.
Can that inverter do 50w ?

With a segment pulling 60ma, another 40ma would be a 3kohm resistor (5w, 10w to be safe).

Most I know on the inverter is it puts out 160v ac with an input of up to 18v dc.

Then you will have to proceed without knowing - or stop here.