Hey ! We have those two buttons type.
It only last 3 months though.

 

It seems US toilets are rather different to UK ones. Mine has two buttons on the top - one gives a full flush and one gives a reduced flush.

Many new US toilets have dual flush ( I have one).
The old ones have a flapper valve with a chain/strap to the handle.

 

Hey ! We have those two buttons type.
It only last 3 months though.

Mine's been going 11 years and counting.

 

Mine's been going 11 years and counting.

It's the outstanding quality of our water

 

I use something like this in an apartment I own (link).


They are a little pricey, but being all plastic they do not have corrosion issues like the metal chains do. I was replacing metal chain flappers every 6 to 9 months.

I get maybe 5 years out of this. Failure has been the external handle. No rust issues.

 

I use something like this in an apartment I own (link).


They are a little pricey, but being all plastic they do not have corrosion issues like the metal chains do. I was replacing metal chain flappers every 6 to 9 months.

I get maybe 5 years out of this. Failure has been the external handle. No rust issues.

The problem in my area is calcium build up on the flush passage. Then the flapper gets a slow leak.

 

My initial idea was an acoustic sensor. Stuck on the tank, it would hear water running much more loudly than other room noises. Then I thought water running in the sink might confuse it, so I went to a conduction sensor.

This is the first pass at a circuit. It covers everything in my initial post, but by the time all of the details are covered it seemed overly complex for the task at hand, and it still might need a true power-on reset addition.

ak

 

Second pass. I don't like giant R-C timers, but there already was a giant R and I wanted a noise filter on the input, so things changed. This whole circuit can be done with only one NAND gate. The two extra inverters work to put a low voltage on the oscillator capacitor in the non-operating state, to reduce leakage current.

I didn't like wasting the oscillator current, and need a very asymmetrical output anyway, so the oscillator capacitor is charged through the beeper to get double-duty from that energy.

All values are approximate. X1 is a self-oscillating piezo beeper. The idea is to pick C2 for the length of beep time, then pick R2 for the inter-beep time. R1 sets the standby current, then C1 sets the turn-on delay.

ak

 

Have you tried probes in the cistern to see if there might be issues with condensation on them or bridging them?

 

Have you tried probes in the cistern to see if there might be issues with condensation on them or bridging them?

And the current will corrode one of them away unless an AC feed is used.

 

Have you tried probes in the cistern to see if there might be issues with condensation on them or bridging them?

And the current will corrode one of them away unless an AC feed is used.
Though you could use carbon rods to avoid that problem.

 

Just stopping by to say the clothes washer fill switch is a good idea. They are dead easy to use and mechanically strong.

 

If your still looking for other ways of doing this, here is a suggestion for eliminating any probes.