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Back from a YouTube ban! Faulty soap foam dispenser - with schematic

Published on Fri, Jun 21st 2024 Science & Technology Rectangular HD

If you wonder why there haven't been videos for a while, it's because I received what I believe to be a very unfair strike from YouTube for a harmless 18 second short where I singed the end of my beard with a lighter in a controlled manner.

I bought this unit a while ago for a long term test of different units. Many of the other units had annoying technical issues, including one that saw its own foam and kept squirting more out, thinking a hand was there. And another that would crash and turn off every time foam was dispensed (probably an undersized lithium cell).

These units do tend to wear out over time, and a very common issue is the foam enhancer blocking. I may force some water through the foam enhancer in reverse in this unit to try and clear any debris out of the very fine moussing mesh. It does sound slower than I recall, so it could have an issue with loss of lubricant on the pumps wobble plate, or is perhaps struggling to push the liquid through a clogged mesh.

Nice logical circuitry though, and the software seems to be pretty good too. The standby battery life is exceptional given that the hand sensor remains active 24/7.

The foam pumps in these units are a dedicated unit designed for the many hand-soap or sanitiser foaming dispensers in use. The use of foam instead of liquid soap means that a refill lasts ages, but still gives you the effect of a good portion of soap.

The sensor PCB was very nicely implemented, with it's little black foam surrounds to ensure low infrared leakage between the emitter and detector. A test of the detector showed a massive change in resistance between ambient light and pointing an infrared remote at it. Literally from 10's of megohms to tens of kilohms.


If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:- https://www.bigclive.com/coffee.htm
This also keeps the channel independent of YouTube's algorithm quirks, allowing it to be a bit more dangerous and naughty.


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