Fog Machine controller

Hello,

I'm looking to build an Arduino-controlled fog machine.
Now the problem is: this is my first time hacking a device/machine powered off 230V (Dutch mains standard).

The fog machine is a Martin Magnum 650 (2.66A/230V/620W). It has a (wired) remote with a rocker switch and a status indicator light. I plan on using a relay board (this one) with an Arduino Uno.

I want to replace the rocker switch with the relay board and connect it to the Arduino. This is already sufficient to make it work from an Arduino. Now what I really need help with is the status indicator. I want to be able to see if the fog machine is heated up or not. The status indicator is actually a bit complex. When the rocker switch is pressed, the indicator becomes brighter (doesn't matter if it's heated up or not). And when the fog machine is heated up, the light is really dim but not completely off.

Unfortunately I don't have a multimeter (actually I just ordered one off Ebay) so I cannot really measure the amount of current going through, neither can I measure the voltage. In order to be able to 'read' the status, I would connect the positive lead of the indicator wire to an Arduino pin. For obvious reasons, I would have to limit the current using a resistor. But the voltage should also drop to 5V, right?

Also, is the power going to the remote AC or DC? If it's DC, I can measure it safely using the multimeter I just ordered. The indicator lamp is rated for 10A (fog machine's input current is 2.66A).

Technical specs of the fog machine: http://www.martin.com/spec/compositespec.asp?pp=1&popspec=0&extratext=on&bullets=on&photo=on&region=US&lang=0&product=Magnum650
The rocker switch and indicator lamp/light: NINGBO HAISHU LIHE ELECTRONIC CO.,LTD.

Thanks in advance!

Greetings from the Netherlands,
Jeffrey

Stop and do not go any further until you have a voltmeter and can measure the electrical characteristics of the switch and lamp that you will be interfacing with. Trial and error will just damage equipment and possible injure somebody - measure first, so you know what you're dealing with.

Once you have the meter and are able to measure what's going on, if any part of this product is connected to the mains then assume that all electrical components are at mains voltage unless/until proven otherwise.

Welcome,
Please take PeterH's advice serious.

To measure the temperature you can use a watertight DS18B20 - use Dallas Temperature Control Library -
it goes from -55 up to 125C and is very reliable, accurate and precise.

You can already experiment with it without connecting to the device (just use a cup of tea/coffee)

Regards,
Rob

PeterH Thank you for your advice. I will wait for my multimeter to arrive.

robtillaart I don't think 125ºC max. temperature would be sufficient for a fog machine. I have a spare 100K thermistor laying around which I could use to measure the nozzle temperature. But interfacing with the status indicator would be the easiest way.

What temperatures are reaches in a fog machine? - Sorry, I am a noob on fog machines :slight_smile:

robtillaart:
What temperatures are reaches in a fog machine? - Sorry, I am a noob on fog machines :slight_smile:

The nozzle can reach up to 200ºC.

So no DS18B20

Okay I just got my multimeter (yay!).

There are four wires inside the remote, three come from the fog machine and one is used to connect the rocker switch to the indicator light:

  • Brown (2x)
  • Black/yellow (inside is yellow)
  • Blue

Here's an image of the wiring inside the remote.

My findings so far:

  • Blue is positive
  • The indicator light uses 7mA (10.1V) when heated, 47mA (118V) when heating.
  • Brown (light > rocker) is ground
  • Other brown (fog machine > rocker) is positive
  • 222V is going through the rocker switch

I'm not entirely certain if what I measured is AC or DC. Is there any way I could tell using my multimeter?

I can't figure out what that thing is doing...

It seems strange to have 118V in a 230V device.

It looks like the indicator light is in series with the switch. But, that would mean the light is completely off when the switch is off.

Is there something else in the box we can't see? I see some bare wire or solder in the middle of the blue wire. What's that connected to? Is there a bare wire connected to the bottom of the switch above where you labeled "rocker switch", or am I seeing metal inside of the box? Is that where brown is connected to ground?

I'm not entirely certain if what I measured is AC or DC. Is there any way I could tell using my multimeter?

With the meter in the DC mode, most meters will measure zero (or near zero) when connected to AC. Depending on the meter, it may also measure zero in the AC mode when connected to DC. If you are truly measuring DC, you should see a minus sign when the connections are reversed. Try measuring a battery (DC) to see how your meter responds in the AC mode, or when you reverse the connections.

I re-uploaded the image with the correct readings from my multimeter.

DVDdoug:
It seems strange to have 118V in a 230V device.

The device is rated for both 120V and 230V.

DVDdoug:
It looks like the indicator light is in series with the switch. But, that would mean the light is completely off when the switch is off.

It's not completely off. It's just dimmed. The ground wire from the switch is connected to the indicator light's ground, but the positive wire (blue) going to the indicator light is not connected to the switch.

DVDdoug:
Is there something else in the box we can't see? I see some bare wire or solder in the middle of the blue wire. What's that connected to?

I desoldered the blue wire so I could measure the current going through the indicator light.

DVDdoug:
Is there a bare wire connected to the bottom of the switch above where you labeled "rocker switch", or am I seeing metal inside of the box? Is that where brown is connected to ground?

The bottom wire (brown) on the rocker switch is actually positive. Not sure why they chose brown.

DVDdoug:
With the meter in the DC mode, most meters will measure zero (or near zero) when connected to AC. Depending on the meter, it may also measure zero in the AC mode when connected to DC. If you are truly measuring DC, you should see a minus sign when the connections are reversed. Try measuring a battery (DC) to see how your meter responds in the AC mode, or when you reverse the connections.

An AA battery in DC mode shows 1.54V and in AC mode 2.7V. When I try DC mode on the GND and VCC of the rocker switch, I get 67V when connected properly, and -67V when reversed. However the rocker switch is rated for 250VAC with no rating for DC. AC mode shows 129V (yes, 129V. It was 118V before I took the switch out). Reversing leads in AC mode shows 1.8V.

Okay so the manufacturer confirmed the power inside the remote is all AC.

That means the positive (brown) wire going to the rocker switch is (roughly) 130VAC and the blue wire going to the indicator light is (roughly) 230VAC.

I've already managed to successfully hook up the wires to a relay, but I was wondering if it's possible to add some sort of indicator status detection? I could use the existing indicator light and hook up an LDR to see how bright the light is, but is there an easier way to detect a large voltage drop (230V to 10V)?