Its been close to 15 years since I took a logic design class. I've had some free time lately and have been messing around with easyeda and 123d circuits.
I've recently come across a real world problem I want to design a circuit for but I've been stumped on how to implement it.
Basically I want a circuit that can detect a mains power drop, 5V DC, and turn on a LED that will be powered from a charged capacitor(s). Basically a notification that main power has failed.
I've got the capacitor part down and in my simulations can power the LED for the time I require, only a min or two. Problem is the LED is always powered, even when main power is on. I only wanted the LED to come on when main drops to 0V.
I figured a simple transistor circuit could do it, I've created a couple of simulations but can't seem to accomplish what I want. Any ideas?
Thanks!
I've recently come across a real world problem I want to design a circuit for but I've been stumped on how to implement it.
Basically I want a circuit that can detect a mains power drop, 5V DC, and turn on a LED that will be powered from a charged capacitor(s). Basically a notification that main power has failed.
I've got the capacitor part down and in my simulations can power the LED for the time I require, only a min or two. Problem is the LED is always powered, even when main power is on. I only wanted the LED to come on when main drops to 0V.
I figured a simple transistor circuit could do it, I've created a couple of simulations but can't seem to accomplish what I want. Any ideas?
Thanks!