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Help: hacking fog machine with timer relay Answered

Hello, everyone. I need a little help! I'm not very skilled in circuits, but I have already did something similar with a different device (following some tutorials from instructables); this time the same approach seems not working.

I have a sensor which triggers a timer relay; when the relay is triggered on i would like to switch on my fog machine (which is already turned on and heated) and spread the fog until relay reset.

From the relay I have a COM and the NO(/NC) output.

I need to connect those outputs to my fog machine cable controller (which i cannot unmount completely). I attach here some photos of my circuit.

The first image shows a red area (short circuit!), and two green areas (fires fog): if i connect the relay output there (COM or NO or NC) circuits reacts even if the relay is off.

I have tried connecting the relay out to blue/white wires but nothing happens.

What can i do? I'm starting to think to connect only NO (or NC) to both blue and white wires.

Any help is appreciated.

Thank you so much.

- - - - - EDIT - - - - -

Thanks for the first 2 replies: connecting COM and NO to blue and white cable was the first thing i did, but with no success. I tried again (maybe i was doing wrong), but again no success.

I add 4 new pics of the circuit from above (i have dismounted it). Hope it is much clearer now.

Thanks again for your support.


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1 year ago

I assume the three wires go to whatever makes something in the machine and are not going to the plug.
From your relay COM goes onto the white cable or solder pad, NO goes onto the blue cable/pad.
Like that the fog should activate every time the relay energises.

Jack A Lopez
Jack A Lopez

1 year ago

There is a mental picture you should have in mind, regarding these relay terminals with the funny names: {COM, NO, NC} I have attached a picture which shows the internal wiring of a typical {COM, NO, NC} relay.

By the way, the funny names are actually abbreviations. COM stands for "common." NO stands for "normally open." NC stands for "normally closed"

When the relay coil is off, terminals COM and NC are connected together, and the NO terminal is floating, not connected to anything.

When the relay coil is on, terminals COM and NO are connected together, and the NC terminal is floating, not connected to anything.

The final piece of the puzzle, as far as language is concerned, is to realize the word, "normally" means, "when the relay coil is off." It is kind of some funny language to call the condition when the relay coil is off, the "normal" condition. This kind of implies the condition when the relay coil is on, is the "abnormal" condition.

Regarding the "fires fog" button on your machine there, I am guessing all that button does is connect the blue and white wires together, when pressed.

Thus the way I expect your relay should be connected is to use the COM and NO terminals. Connect COM to blue wire, and NO to white wire. Or connect COM to white wire, and NO to blue wire. Either way, when the relay coil is turned on, COM and NO get connected together. The rest of the time, when the relay coil is off, COM and NO are not connected; i.e. "normally open"