#114 No contact mains detector for Arduino & Pi 🥧(just 10 components)

Safer Mains (Home Electricity) Detection
How to detect the presence of mains electricity (in your home) using a RasPi or Arduino

So I really want a SAFE way to detect mains in my workshop so can check whether I have left the lights, or more importantly, the heater on.

This method is a NO CONTACT method using just a handful of discrete components and costing a couple of pounds (or dollars), if that much!

It's easy to build on stripboard and runs from 3.3 volts to 5-volts. Actually, you can power this with 9v if you want, it will still work.

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PLEASE NOTE THE CIRCUIT DIAGRAM STATES 2N2904 TRANSISTOR. THIS SHOULD BE 2N3904 TRANSISTOR (or any NPN general purpose equivalent, eg 2N2222).

Everything here is in my GitHub:
https://github.com/RalphBacon/Safer-Mains-Detection

This is what gave me the inspiration:
How to build your own non-contact voltage detector article (with video) by Kiran Daware
https://www.jameco.com/Jameco/workshop/JamecoFavorites/non-contact-AC-voltage-detector.html

1PCS 5A Over current Protection Sensor Module AC Current Detection 12V Relay Module
https://www.aliexpress.com/item/1PCS-5A-Overcurrent-Protection-Sensor-Module-AC-Current-Detection-12V-Relay-Module/32858449954.html

An assortment of transistors like the ones I use here (2pence or US 3c each!)
https://www.aliexpress.com/item/BC337-BC327-2N2222-2N2907-2N3904-2N3906-S8050-S8550-A1015-C1815-Transistor-Assortment-Kit-10value-200PCS-Transistors/32687065196.html
Just watch as you open the lid so they don't all get mixed up (don't ask, no, really, don't)

The sketch I used is simplicity itself but does demonstrate the use of a boolean variable to keep track of the last state.
It's in the GitHub:
https://github.com/RalphBacon/Safer-Mains-Detection

If you like this video please give it a thumbs up, share it and if you're not already subscribed please consider doing so :)

My channel and blog are here:
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https://www.youtube.com/RalphBacon
https://ralphbacon.blog
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