I switched some electronic candles to be powered by a power adapter instead of batteries but when I power them up I noticed they all now "flicker" (which is a feature) at the same rate probably because they all use the same circuit. With batteries this isn't a problem because you'd turn them on/off at different times but now they all turn on at the exact same time when I plug it in. Is there a cheap way to delay these at different rates, possible with simple passive components?
This is impossible to do well with only passive components. It would require that your candles switch on/off at a precise voltage threshold, plus an RC circuit which is able to source any sensible amount of current with a delay of several seconds will have ridiculous component values.
Instead, you could implement one of the NE555 timer delay circuits, which can be easily found online. Or you could design a circuit yourself. You will need:
- an RC divider to create ramping up voltage
- a comparator to transform that voltage into a digital signal
- a voltage divider to generate the threshold value for the comparator
- an active switch (BJT, MOSFET) which would switch the candle on based on the digital signal
Maybe something like that is good? Put higher C values for higher delays. You will have ~1s delay for each 50uF added. Take a ~1V voltage drop on Q into account. Use the link "simulate this circuit" then in "Run" menu "Time domain simulation" to see the results. Use lower resistors and higher capacitors if your candles ar drawing more than 10mA.