I am looking for the proper piece of hardware to do what I'm looking for on my current prototype machine build.

I want a timer to begin counting upwards in seconds when a switch is activated, and reset back to zero when the switch is deactivated.

I know I can probably make some kind of Arduino based set up for this, and I know for a fact how to do this with a PLC/HMI, but I am having a hard time finding a cost effective, easily solution for this as its only a prototype at this stage. Everything I search keeps pointing me towards what looks like timer relays, but I'm not sure if that's what I need. I don't need to throw any outputs at any set points, basically just a cycle time readout for the operator.

EDIT: I suppose I could also use a 1 second pulse generator wired to the input on a basic counter, but lets see if we can find the right stuff..


  • $\begingroup$ Supply voltage, maximum elapsed time, resolution, ...? I presume you won't consider a water clock with a scale on a float and a pair of solenoid valves to fill at a controlled rate and drain it rapidly? $\endgroup$
    – Transistor
    Commented Jun 7, 2021 at 14:37
  • $\begingroup$ 120vac or 24vdc, max time would be 999 seconds, resolution should be seconds. Water clock sounds awesome, but a little to involved for this prototype. $\endgroup$
    – Corey
    Commented Jun 7, 2021 at 14:39
  • 2
    $\begingroup$ Look for "resettable timer" or this image search. $\endgroup$
    – Transistor
    Commented Jun 7, 2021 at 14:46

1 Answer 1


Omron makes a wide variety of industrial timer modules which can count down a preset number of tenths of a second all the way to hundreds of hours and then close or open a set of switch contacts and reset themselves. A new one from one of the on-line industrial supply houses might cost about 150 dollars new, or 20 to 40 dollars for a used one at an industrial surplus house.

They can be configured to actuate a switch when power is first applied, count down for a preprogrammed time, and then reverse the switch action when the internal clock counts down to zero.

They contain multiple sets of switch contacts and can be connected up to perform a number of useful tasks, and it sounds like one of these would be what you want.


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