Could be the problem.
Put your DMM in DC AMPS mode, 10A range, use the DMM leads to connect the ARC wires together, this will tell you the current needed to flow when you connect them together.
Tom... 
My DMM seems to be faulty when i measure current so I placed a 10 ohm resistor b/w the two connections of electric arc and maximum voltage across resistor came out to be: 1.45 V, that means around 145 mA. The actual current should be around this.
That is average current not peak current.
note that average current was 85 mA. 145 mA is calculated by observing the highest voltage value that DMM gave.
I am really stuck now, optocoupler has not worked for me neither SSR. Resets still happen. Please guide me on this.
Hi,
Is BAT1 supplying current to power the electric arc or just the control to the electric arc?
If remove the BAT1, will the arc circuit still trigger and operate if you short the two connections together?
What is the electric arc circuit?
PLEASE post a link to specs/data of the arc circuit.
What SSR did you try?
Specs PLEASE.
There are higher current spec opto couplers, who is your electronics part supplier?
Thanks.. Tom..
PLEASE post some images of your project, especially the arc circuit.
You're asking a valid question and I just realized this few hours ago. BAT1 powers the electric arc/igniter circuit, and I was mistakenly placing a relay/optocoupler between them to control it through the Arduino. (directly cutting off the power supply through relay) However, after studying the igniter module more closely, I am now powering the igniter circuit by BAT1 all times. There's a control signal wire from the igniter module itself, which I can now use to enable or disable the igniter module.
I'll share the updated schematic, highlighting the internal connections of the igniter module.
Anyway, after changing the connections and trying to control the igniter circuit through the control wires using the Arduino, the Arduino still resets when the sparks occur. I was really excited, thinking I had solved the issue after discovering the control wires, but I'm back to square one. It still doesn’t make sense.
It’s a Chinese module without any specific documentation, but I found a similar one that looks almost identical, with the same number of wires. Here’s a link to it on AliExpress:
https://www.aliexpress.com/item/1005005701378826.html
Here's are some pictures of the module that I am using so you can verify the similarity:
These are the connections labelled as shown from aliexpress website:
Note: I can't seem to find the datasheet for this module or some official documentation.
I used this:
Important Observation:
When I remove the switch control connections from the relay and short them directly, the igniter module is enabled, and I can see the sparks, while the Arduino doesn’t reset. However, when I bring these shorted connections near the LCD, the display shows garbage.
But as soon as I reconnect the control switch wires to the relay (making a physical connection with the rest of the circuit), the Arduino starts resetting when the igniter circuit is enabled.
I’m not sure what’s going on. Is EMI traveling through the wires and disrupting the Arduino? It’s clear that EMI isn’t affecting it through the air—only when physical connections are made.
anyone who can help me ?
That is a SSR that only switches AC loads, it will not switch DC loads.
There are "so called" DC SSRs but all they are just a bunch of FETs in a convenient package.
The problem with your opto isolators not firing the arc might be due to rise time on the ignition circuit not being fast enough.
I finally solved the issue by using double isolation and a separate power supply for the relay. Here's how it works:
The Arduino sends a signal to an optocoupler, which activates its transistor. This sends a low signal to the relay, which is powered by a separate power supply. The relay then completes the circuit for the igniter's control. With this setup, the Arduino no longer resets, and the LCD doesn't show garbage.
Using just the optocoupler or just the relay didn’t fix the issue. I also tried powering the relay from the Arduino’s power supply, but that allowed interference through the ground wires. By isolating the system in two steps—first with the optocoupler, then with the relay—and using a separate power supply for the relay, the problem was resolved.
I’ve attached the schematic of the solution that worked for me. Problem solved, finally!
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Thanks for the update. All too often supplicants just vanish from the forum the minute they get their project working.
Nah that's a wrong practice, this might help someone in future.
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Glad you got it working, well done.
And I think this was because, as I said:-
Using a relay gave you that rapid rise time on the ignition circuit.
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