How to troubleshoot nano clone resetting randomly

[bobloblob]

I used an Arduino Nano clone and uploaded fogduino to it last year for Halloween to control a fog machine, but had issues running it due to it resetting randomly.

The goal is to create nearly continuous fog as this allows the fogger to heat while also pumping fog -- something they do not do typically. The basics are the nano will average 10 readings from a Max6675 Module + K Type thermocouple and if in the right temp range, it will control the relays that pass 120v power to the heater and/or 120v to the liquid pump. Info on temps are displayed on an OLED screen and I'm powering the Nano from a 5v 700mA power supply. I reused 3 old momentary buttons for selecting modes/settings.

Here are the components I bought -- everything was from amazon:
Nano Clone: Amazon.com: 5pcs for Arduino Nano ATmega328P CH340 Microcontroller (5pcs) : Electronics
Thermocouple: ACEIRMC DC 3-5V MAX6675 Module + K Type Thermocouple Temperature Sensor Thermocouple Sensor Set M6 Screw Compatible with Raspberry Pi Arduino (6pcs): Amazon.com: Industrial & Scientific
Relays (x2): https://a.co/d/eNB2CC2
Power Supply: diymore 5 PCS AC DC Converter Module, Universal AC 110V 120V 220V 230V to DC 5V 700mA Isolated Switching Power Supply Board Step Down Buck Converter : Amazon.ca: Electronics

How do I troubleshoot why the unit restarts--aside from just start replacing components? Is there something obvious based on the components that I should not have used? I do know that this behavior continued after replacing the nano.

[MaximoEsfuerzo]

There are probably electrical noise problems.
Please attach a diagram of how you made the connections, including the power supply.

[bobloblob]

I'm a hack -- I don't have a diagram and barely know what I'm doing. This was soldered onto proto board based on a forum post and reading the code to confirm the pinouts. There is no filtering unless in was built into the components purchased (which I doubt, as I bought the cheapest possible things)

I don't have the unit beside me -- I'll try to take and annotate some pictures of the connections tomorrow. I believe the power supply is connected to the 120v coming into the fogger (same power later being switched by the relays) and I believe the 5v is directly connected to the nano Vin.

Would using the above linked relay cause more problems than an SSR like this: Artshu Solid 2 PCS State Relay Module SSR-10DA 250V 3-32V DC Input 24-380VAC Output: Amazon.com: Industrial & Scientific. The SSR was in the original build, but instead I used the others due to cost and not understanding the value the SSR might provide in this application compared to the other unit. I believe I added a snubber, but I'll double check.

[johnerrington]

@bobloblob

I don't have a diagram

Then look at your hardware and make at least a connection diagram

How to make a schematic you can post.

When you submit a question on the forum you will usually need to add a schematic (circuit diagram). The tutorial that follows will explain some ways to create a useful image; however lets start by explaining how to add the image to your post. Its easy. Having created the image all you need to do is : Save the image somewhere convenient - maybe your desktop Start your post, and place the cursor (insertion point) where you want the image to be shown; [upload image to forum] 3: click th…

[bobloblob]

Here's a rough sketch of the system. Not sure if it'll help -- If anything is totally weird, I've probably just screwed up the diagram as the system functions for a while before the nano glitches and reboots