andrew2022
New Member
i need an LED to display wether the mains power (230V) is on or off. whats the best way to do this without a transformer? can it be connected to a rectifier directly to the mains (obviously with a resistor in series)
Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature may not be available in some browsers.
panic mode said:...and if you do use caspacitor to knock down voltage, please do yourself
a big favour and put a resistor IN PARALLEL with C1 capacitor
(something like 100k 1W for example).
circuit as shown above would work but when you unplug it,
there is nothing to drain down the capacitor charge. (are you ready
for some nasty zapps?)
Although wouldnt the LED drain the cap after switching off?
TheOne said:If we do some sums, the peak -ve or +ve voltage over this cap will be about 169v. Looking at the energy stored in the cap, will be about 7mJ
JimB said:TheOne said:If we do some sums, the peak -ve or +ve voltage over this cap will be about 169v. Looking at the energy stored in the cap, will be about 7mJ
That is true for a 120 volt supply, the original post stated 230 volts, so the peak will be 325 volts and the energy will be about 24 mJ.
JimB
panic mode said:Although wouldnt the LED drain the cap after switching off?
how?
if you turn the circuit off with a switch (inserter in series with the circuit)
or if you simply unplug the circuit from the receptacle, C1 would be
part of open circuit.
mstechca said:Why not use a lightbulb?
or if you really want to use an LED, make or buy a DC adapter rated 9V or less. connect a 60 (or more) ohm resistor in series with the LED and hook it up to 9V.