Hello ! English is not my first language so sorry if i make mistakes. I was wondering about the kind of clock inside washing machines when you set a program for later, mine allows me to chose between a delay of 3h, 6h and 9h by pushing a switch and there’s no screen. What’s the most efficient way to build it ?
In: Engineering
Modern machines have a microcontroller inside, a tiny CPU (computer) with some basic additional functions all on the same silicon chip. A very common function is a simple real-time clock, basically a circuit that generates pulses at a constant rate attached to a counter. The CPU can read the counter to see how many pulses have happened since the counter was turned on or otherwise set back to zero.
If the timer survives the machine being turned off for a while then that probably indicates there’s a clock with battery backup running all the time. Silicon chips that do this all in a single device, just add a tiny button cell for power, are very common and cheap.
The rest is just programming the microcontroller to use the clock features to create a timer-delay. The old days of building special electronics or mechanical devices to implement complex functions like this are over.
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