My wife gifted me this super cute mini miffy diorama from a gachapon. It uses two 1,5V cells and has a tiny led in it. I would really love to to add a 24h timer. ( it should stay on for 4 hours after turning it on then go to “standby” for 20h before turning back on) Do you guys think an attiny85 is the right thing for the job? Sorry of the question is dumb in any way. I am absolutely not an electronics guy.
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ATTiny would definitely work. Ive use them for really really long timer systems with some trial and error.
You should maybe just look at a bigger battery depending on what lifetime you would expect? They are not exactly super low power(at least the ones I have used)
Is there a more low power alternative?
You could go with an DS1339 which is an RTC with two programmable time of day alarms. If you only need timing you might as well do that. But if electronics isn’t really your thing then just add a bigger battery for the attiny85, make sure to run it at it’s lowest clock speed.
If it doesn’t matter if it’s a few seconds too late or too soon an ATtiny 85 is good. If you need more accuracy you probably need an additional RTC.
You could also use a crystal for the ATtiny and get the same accuracy as the RTC. It should be accurate to about 20-30 seconds per month with a good crystal.
The internal oscillator only has an accuracy of around 1% after you calibrate it. It would be off by over 7 hours after a month. It’s also quite sensitive to voltage and temperature changes.