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.
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.
what is the formula for calculating the resistor i need for an led based on 120 volt half rectified mains given 'x' for led voltage and 'y' for led current draw? thank you!
Using a capacitor as a dropper dissipates less power and is a better idea, if you dont want 2 leds use a 1n4001 in place of one of the leds.
Be carefull with any circuit connected to the mains - dangerous.
As DP says, the cap is a better route. A current-limiting resistor for 120vac can be big and radiate as much power as a small incandescent lamp, making the LED pointless if you used the lamp instead!
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