I'm trying to connect a timer output wirelessly to another circuit. These are on two separate power lines (different phases, circuit, long distance), so I thought of connecting them wirelessly, I'll use a standard low cost remote controlled switch which have separate on and off push switches.

Now I need to detect the power output from the timer, when there's power, a single signal should be sent to trigger the "on" switch, when the power drops off, another signal to trigger the "off" switch. The signal should be short, low voltage, like 0.5seconds only and meant for a transistor.

Ultimately, the power change should be detected directly from the timer's output which is 240v AC.

The output signal can be either separate wires for on and off signals, or a single wire with positive and negative trigger for on/off.

See the diagram below for better explanation.

enter image description here

  • 6
    \$\begingroup\$ What’s your question? \$\endgroup\$ – Blair Fonville Feb 17 '19 at 12:25
  • \$\begingroup\$ Rectifier (or peak detector) + schmitt trigger + two timers (one shots). \$\endgroup\$ – Artur Feb 17 '19 at 18:36

You can use a current transformer around one of the mains wires to sense if current is flowing in it. Here is an example of one that clips on...


Whenever there is AC current flowing the mains wire (timer is on) then an AC voltage will appear across the output of the transformer. Depending on what you are trying to do, you can connect this output to a rectifier + cap and then to a transistor gate if the voltage is high enough, or to an op amp if you want adjustable turn on current threshold. You can also add, say a 555 timer in one shot mode if you just want something to happen only when the timer turns on (or if the timer is controlling an inductive load like a motor, just set the threshold high enough that the transistor only turns on when the motor first starts).

| improve this answer | |

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.