On/Off swtich that simulates a button push

[lz300]

I wish to connect a humidistat to a remote-control switch for powering on a humidifier. The humidistat has an open circuit until the desired humidity is reached, then it closes the circuit. To tie in with the remote control switch, I need to be able to simulate the pressing of a button in both scenarios: when the humidity reaches the desired level, and when it drops below that level.

Someone suggested a one-shot timer, but if I understand correctly, it is triggered by a pulse, which is the opposite of what I'd like to do.

Is there anything out there that will trigger a pulse when the input is closed, and trigger another pulse when the input is opened again?

 

[eblc1388]

Someone suggested a one-shot timer, but if I understand correctly, it is triggered by a pulse, which is the opposite of what I'd like to do.

That is partly true.

What he doesn't also tell you is that one can select either the rising edge or the falling edge of the input signal to trigger a one-shot.

A common CMOS IC 4538 comes with two monstables built-in and allow user to select either triggering options on each of its monostable input. So one can select falling edge trigger on mono#1 and rising edge trigger on mono#2.

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You now just combine the output of these two monostables and get what you wanted. Please note that the component values are not correct for your application as I have to trim them so the simulation goes faster. It is just to prove the idea actually works.

 

[BaCaRdi]

Perfect advise

Also I would state, a PIC will do that plus a WHOLE LOT more.

I would say try the PIC, learning the PIC microprocessor will allow you to use very discrete components instead of needed a truck load.

Now don't get me wrong they are still needed in circuits but this will allow very flexible use in your studies.

Most PIC's have allot more hardware modules built-in so you can use what is needed for the project at hand.

Best of luck, came to the proper place for this task, there are many excellent people here, and willing to help.

I would suggest going to a member's site :

blueroomelectronics
**broken link removed**

He is a proud member here and he takes support very seriously.

I wouldn't be recommending him if I didn't trust his products and services %200

Most here know PIC's enough to find the issue no matter what.

Again we love questions


Smile it's fun!
-Marc

That is partly true.

What he doesn't also tell you is that one can select either the rising edge or the falling edge of the input signal to trigger a one-shot.

A common CMOS IC 4538 comes with two monstables built-in and allow user to select either triggering options on each of its monostable input. So one can select falling edge trigger on mono#1 and rising edge trigger on mono#2.

You now just combine the output of these two monostables and get what you wanted.