Relay to turn on low power AC circuit

Thread Starter

Dmm

Joined Apr 13, 2015
70
I am wanting to turn on and off EL wire, which is a small wire that glows visible light when AC is applied to it, with arduino or an ATTiny85. The EL wire comes with a transformer that runs on 2 AA batteries. It outputs 140v AC. I bought a solid state relay, but it does not work as expected. No controller, just me touching the wire to activate the relay. The relay will turn the AC side on, but when removing the control wire (connect to ground) the relay stays on on the AC side and the EL wire does not turn off. The EL controller has a flash function and if I activate that all this works, as I suspect the flashing from the controller resets the relay, or something like that.

After a lot of searching, it sounds like the current I want to run on the AC side might be too low. Doesn’t make much sense to a noob, but I think that’s what is happening. The SSR uses the G3MB-202P and the data sheet shows a load current of 0.1 to 2 A and I measured the EL wire only using 7mA. One site said to put a resistor in parallel with the load. I tried a 10k but it did not work (nothing lit up, including one EL wire connected directly to the controller and not the relay.) I’m not sure how to calculate what I would need either, and I didn’t want to spend too much time with doing so as I know my limitations and didn’t want to do something bad.

Is there a better way to control a low power AC circuit? I tried a coil type relay and it works. Was just trying to get away from the noise it makes. Would be nice to get the SSR working as I bought an 8 channel SSR relay for this project.
 

Thread Starter

Dmm

Joined Apr 13, 2015
70
Can you post a schematic or wiring diagram of the EL wire?
It’s a 2 wire JST connector that I put jumpers in to connect to the SSR. If you are asking about the AA battery pack thing, I don’t have that schematic, and I haven’t opened it up to look, and probably won’t. It just outputs an AC signal.
 

Thread Starter

Dmm

Joined Apr 13, 2015
70
I could draw something up a little later…but from the JST I put one wire to the SSR, then from SSR to EL wire. Then the other EL wire connection goes back to the JST which is the AA battery controller.
On the control side, I have a 9v battery going to a breadboard power supply to get 5v. Then 5v and ground to power inputs on SSR, and then I have another wire connected to 5v on breadboard, and I just touch that wire to the input/control pin on the SSR to control it. The SSR does have an LED indicating active which does work when connecting and disconnecting the control wire.
 

sghioto

Joined Dec 31, 2017
3,665
The relay will turn the AC side on, but when removing the control wire (connect to ground) the relay stays on on the AC side and the EL wire does not turn off.
Not sure but possible the internal snubber circuit in the SSR is causing the problem. Not enough leakage to turn on the EL wire when first connected but enough after the SSR is activated. Similar to how a coil relay works. Higher voltage to operate but much less voltage to hold the contacts closed.
 
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Thread Starter

Dmm

Joined Apr 13, 2015
70
Here are some pictures of my setup with the coil relay (works like I want it) and the SSR which does not work as I want it to work. The SSR will turn on the EL wire....but it won't turn it off.
 

Attachments

sghioto

Joined Dec 31, 2017
3,665
After reviewing your post I see how you wired it which should have worked. However I believe the problem is the SSR module.
Can you tell from the pc board how that green component is connected to the SSR? I'm assuming there are 8 of them, one for each channel.
 

djsfantasi

Joined Apr 11, 2010
8,652
From the Omron site regarding why an SSR may not turn off, I think sghioto may be onto something. From this article, they have several suggestions on fixing the problem. I think this one applies.
2F23FD70-B8F3-4DCB-A23E-86BA56088B06.jpeg
Their solution is to bypass the load with a resistor in the range of 5kΩ to 10kΩ. They recommend a 3W resistor, but I think the EL wire doesn’t draw that much power. A smaller rated resistor might work. Do you know the wattage rating of the wire or inverter?
3960DE86-F30C-407C-9664-90B1DE1EBB2E.jpeg
Experiment with this and see it it helps.
 

Thread Starter

Dmm

Joined Apr 13, 2015
70
After reviewing your post I see how you wired it which should have worked. However I believe the problem is the SSR module.
Can you tell from the pc board how that green component is connected to the SSR? I'm assuming there are 8 of them, one for each channel.
Yes there is one of those green parts next to each relay. And looks like it is connected to pin 2 and the left screw post.
 

Reloadron

Joined Jan 15, 2015
7,075
Since the relay approach works and the SSR doesn't my money is on using the SSR. SSRs have a leakage current which I have been bitten by before. Those EL wires draw a very low current. Unless the load on the SSR is high enough to exceed normal leakage current the EL may come on and stay on or simply always be on. When bitten by this I just used as posted above, a bleeder resistor in parallel with my load.. Using Omron as mentioned above as an example looking at this data sheet on page 5 note the mention of leakage current. I would do as suggested and add a resistance based on voltage and more current than leakage current to calculate the wattage.

Ron
 

djsfantasi

Joined Apr 11, 2010
8,652
Can you tell from the pc board how that green component is connected to the SSR? I'm assuming there are 8 of them, one for each channel.
sghioto, what do you think that is and what does it do? My guess is that it’s a bleeder resistor on the input. I’d try a bypass resistor across the EL wire on the output, per the article.
 

sghioto

Joined Dec 31, 2017
3,665
My guess is that it’s a bleeder resistor on the input.
Possible from what I read about from this article since the SSR is controlled by a transistor on the module.
1668391151888.png
However the location of it and since it appears to not have any identification makes me think it's actually connected across the output of the SSR, maybe some transient suppression. Dmm thinks it's connected to pin 2 of the SSR which is one of the output pins.
 

sghioto

Joined Dec 31, 2017
3,665
One experiment would be to remove that green component from an unused channel ( I think you only need 6 correct?) and try that.
Would only need to disconnect one end of it.
 

Thread Starter

Dmm

Joined Apr 13, 2015
70
From the Omron site regarding why an SSR may not turn off, I think sghioto may be onto something. From this article, they have several suggestions on fixing the problem. I think this one applies.
View attachment 280623
Their solution is to bypass the load with a resistor in the range of 5kΩ to 10kΩ. They recommend a 3W resistor, but I think the EL wire doesn’t draw that much power. A smaller rated resistor might work. Do you know the wattage rating of the wire or inverter?
View attachment 280624
Experiment with this and see it it helps.
The EL wire does not pull that much power at all. Only 7 mA.

If I add the 10k resistor only, the wire connected directly to inverter will turn on (expected) but goes very dim when activating the SSR, and the wire connected to the SSR does not come on at all when activating by applying the 5v to the SSR input. And, then when I remove the 5v activating the SSR the wire connected to inverter will stay dim, until I power cycle the inverter then it will go bright again.

If I add a 0.1 uF capacitor and the 10k resistor the wire connected to the inverter is very dim, and the wire connected to SSR does not come on, and when activating the SSR by the 5v the wire connected to the inverter will go off.

Then I replaced the resistor with a wire, 0.3 ohm, and the SSR activated the wire connected to it, but it will not go off. Then I thought from that article it says 100 ohm /1W…does that mean I should use … 140v x 0.007 A = 0.98 W…about 1W, so I tried a 100 ohm resistor and that did not work - the wire connected to inverter would turn off and on as I connected the SSR! Desired effect, wrong wire! The wire on the SSR would come on and stay on even after disconnecting the SSR. I also tried 82ohm & 15ohm, and get the same thing.
 

Thread Starter

Dmm

Joined Apr 13, 2015
70
Possible from what I read about from this article since the SSR is controlled by a transistor on the module.
View attachment 280625
However the location of it and since it appears to not have any identification makes me think it's actually connected across the output of the SSR, maybe some transient suppression. Dmm thinks it's connected to pin 2 of the SSR which is one of the output pins.
Yes, pretty sure it is on pin 2 at one end, and output screw terminal at the other. It has “2A” and a symbol I can’t quite make out on it. It looks like an L with an F next to it…or an IF that is underlined with the underline touching the Bottom of the letter I and F. Camera can’t quite focus in on it. The board is rated for 2A on output (at least that’s what the Amazon description says, I won’t run it near 2A at all.) Maybe some type of fuse?
 

Reloadron

Joined Jan 15, 2015
7,075
OK so you have a 7 mA load which is really not much of a load. Your SSR leakage current likely well exceeds the load current. That is why you are seeing the symptoms you are seeing. You add a resistance across your load which exceeds the leakage current. This is what has been pointed out and linked to. Do you have a data sheet link for your specific SSR? That will tell you the leakage current specifications. Look at post #11 and the drawing.

Ron
 

Thread Starter

Dmm

Joined Apr 13, 2015
70
Probably getting little past my knowledge on what to do now. But the links and sites I could find seem to say same thing that you need more current on the load side. I do have a longer EL wire I could try wiring up to try to get over the 0.1A that is stated in data sheet for load current, but that’s for another day.
 
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