Timed switch for a pump

[Meaty]

Ok, I'm a newbie to both this forum and electronics fabrication so please forgive me. I recently retired from the Army and was a mechanic for 20 years so this isnt my cup of tea. I am going to school now and am working toward a BS in Mechatronics. Anyway, I'm trying to make something to control a pump that will turn the pump on for 3-4 seconds, wait 45 seconds and then pump again for 3-4 seconds. Ideally I would like to have a switch that you press as many times as you would like it to spray and the controller count them and spray the appropriate amount of times. It has to run off of 12-14 VDC and be as small as possible.

 

[Okada]

This can be easily done. Provide datasheet of your pump. A Timer Interrupt has to be used with toggles the Timer Interrupt between between ON time (3-4 seconds) and OFF time of (45 seconds). A counter has to be used for counting the delays inside the timer isr. When state is ON state then pump should be turned ON and delay counter counted for 3-4 seconds and when counter expires the pump has to be turned OFF and counter has to be cleared and state has to be toggled to OFF state and counting has to be done for 45 seconds. This has to be a cycle till pump ON/OFF button is in ON state.

Another three buttons can be used one for SET/RUN and two for INC and DEC. Using this you can set the number of times the ON/OFF cycle has to repeat. This way you can set any number of repeat cycles for the pump.

I can help you with the coding.

 

[betwixt]

Okada proposes one solution.

On/off control alone can be done easily with simple timer circuits, as can counting but by the time the tasks are combined and presumably some indication of the number of cycles is added, a part hardware and part software solution is easiest. You also have to consider factors like switch debouncing, although pressing a switch once may be one physical operation, in an electrical sense, the switch contacts never simply close and open, the elasticity of the switch materials and the brief "partially connected" point where the contacts make and break usually produces many pulses which you obviously want to ignore. Also consider you probably want a display to show how many times you set the spray to operate and maybe how many of those remain to be executed. The display could be LED, LCD or even OLED but each has a different way of being driven.

So please give more information:
1. the pump ratings so we can advise on how to control it's power feed.
2. does it need a display and if so, what type do you want. (LCD = easiest but physically bigger, low power consumption / LED = smaller but uses more power and support circuits)
3. are you able to program a simple microcontroller? (not difficult but steep learning curve!)

Brian.

 

[c_mitra]

, I'm trying to make something to control a pump that will turn the pump on for 3-4 seconds, wait 45 seconds and then pump again for 3-4 seconds...

Pumps are driven by electrical motors. It will be good to know the power rating of the electric motor driving the pump.

It is not a good idea to start-stop electrical motors, particularly big motors. Motors have inertia and they take time to start and time to stop. When they start, they take a surge of current.

It is of course possible to overcome the stress on the motor by using a oversize motor. But seriously speaking, I would suggest you use an electrical clutch.

To keep a count and spray as many times please consider using a simple microprocessor.

 

[zsolt1]

hi,
if you can get this type of timers you can probably easy solve this

I was surprised how many periods can be set for weeks . It does not reset if disconnected