I have a automatic liquid drip project, which works based on timing.

Basically there are three manual switches and each switches will select different delays such as 2 min., 3 min. and 4 min.

When first switch is pressed, the 3v motor controlled dropper will ON only after 2 min. delay and also it OFF after 2 sec ON. Then, the same thing should happen for every 2 min. delay.

The other two switches will select to set the delay into 3 min. and 4 min. respectively for the same above operation.

Now, my question is that, how I can build such circuit using ICs. The only thing is that the circuit should not take more current during its OFF state (no dripping time duration) and also works at about 4.5V. Is there any possibilities ?

  • \$\begingroup\$ Yes plenty of possibilities. But we don't "design on demand" here, you can present your ideas (not what it should do but how to make it) and then we might comment. The simplest solutions is probably a microcontroller, have you looked at what an Arduino can do? Go on instructibles.com to see how others do this. \$\endgroup\$ Feb 14, 2021 at 12:11
  • \$\begingroup\$ There are many solutions like this using binary and Johnson counter with some gates. that are simple but if you learn how to use a uC but more useful in long run, it may be hard at first then simple . ti.com/lit/ds/symlink/… You need a 1 minute counter and a 2 second counter or One-shot and a FET switch. 2 to 15V counters are no problem, otherwise uC < 5V too \$\endgroup\$ Feb 14, 2021 at 13:39

1 Answer 1


This very clearly calls for about any microcontroller:
It's a discrete-input discrete-time (that's the definition of digital!) control problem.

The power consumption of microcontrollers is negligible.

Programming a microcontroller is way easier than implementing something analog that allows for such large time delays with a reasonable degree of repeatability.

So, get yourself some microcontroller board - an arduino, a clone thereof, some ST Nucleo board... the choices are endless.

  • \$\begingroup\$ If you are worried about power consumption there are some MCU like the PIC XLP or the whole MSP430 line which have standby current in the µA range (even less in some cases) \$\endgroup\$ Feb 14, 2021 at 13:19

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