• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Low peak detector and alarm system

Not open for further replies.


I have a signal around 500Hz that is roughly sinusoidal and has a peak voltage of around 4v when all things are well. When things go wrong every 6th peak is low at about 2v. I am trying to detect this low peak and activate an LED (also if 2 peaks every 6 are low a second LED is lit).

One problem is the whole siganl can be down to half its value or anywhere in between, so a good peak may be 2v and a bad one 1v. So I have tried to extract the DC level of the rectified signal to use as a floating referance to compare the peaks to. If a peak falls below the DC threshold it should light a LED.

However I am able to detect the low peak yet.

Any ideas would be most welcomed.

The circuit at the moment is:-


Not open for further replies.

Latest threads

EE World Online Articles