This is slightly off topic, but I want to be able to run an LED from the mains without any transformer.
There used to be a circuit in the Dick Smith catalog, but this is long gone.
Can someone enlighten me?
I want to be able to connect the mains to an optocoupler, and use it's output as a "Mains-failed" alert on a system.
The mains drives the LED in the opto - if the mains fails, the opto drops out and the PICAXE circuit picks up on this.
An opto with the right isolation figures should be happy enough with this idea, but how to drive the LED?
I currently do this with a industrial relay with 230v coil, but they get quite hot when energized all the time, which I am uneasy about.
I am dubious of the single resistor idea at mains potential...
There used to be a circuit in the Dick Smith catalog, but this is long gone.
Can someone enlighten me?
I want to be able to connect the mains to an optocoupler, and use it's output as a "Mains-failed" alert on a system.
The mains drives the LED in the opto - if the mains fails, the opto drops out and the PICAXE circuit picks up on this.
An opto with the right isolation figures should be happy enough with this idea, but how to drive the LED?
I currently do this with a industrial relay with 230v coil, but they get quite hot when energized all the time, which I am uneasy about.
I am dubious of the single resistor idea at mains potential...