No need to draw a new one Al, thanks anyway
I know about the ground symbol but what I mean is to clarify just the vertical lines on your schematic. So starting from the left we have the 120VAC line coming in, then the 2nd vertical line I guess represents the return line to load to complete the on/off switch function.
Then the 3rd and 4th vertical lines must be the connection to the switch
Is this correct?
Hi,
The dark 'arrowhead' looking symbols are diodes. The lead with the short thick line is the cathode, the side with the back of the arrowhead is the anode. There are two diodes in this circuit and they have to be rated for 400v or better (because of the line reversal and the cap voltage when it is charged up.)
THe "120vac" round circle with the squiggle in the center is the AC line voltage drawn as a source.
The line comes out of the top and then turns right, and then goes to a 'vertical line' and that is the left side of the capacitor. The lead connects to one leg of the capacitor. Then the right side of the capacitor is another short vertical line, and the lead coming out of that side connects to the resistor R1 on the left. R1 on the right then connects to a point (node) that connects both to the upper diode anode and the lower diode cathode. The lower diode anode goes to ground. The upper diode cathode goes to both the LED and to C2 the other cap if you use that other cap. It goes to the LED anode and the LED cathode goes to ground. The upper diode cathode also goes to the top of C2 which is a narrow horizontal line, and the other narrow horizontal line is the other plate of the capacitor and that connects to ground via it's other lead.
All the ground connections (there are a total of four of them, one being the white AC line) go to the 120vac white wire.
Just to recap the capacitor is a 0.5 microfarad capacitor and it must have a rating that is rated for AC line voltage operation. This means in the data sheet it will say "rated for constant AC line voltage" or something like that. It might not even have a DC rating like many caps do.
I think people also use ceramic caps for this purpose.
Just to note again, the resistor R1 should not get hot because it only has to dissipate on average about 110 milliwatts, which is less than half it's power rating.
You might also want to note that the connection for the 'other' diode (lower diode here) is not the same as when using a resistor alone because it has to conduct when the incoming line voltage goes negative. In a resistor only circuit that diode goes on the other side of the upper diode and conducts only when there is a surge of a relatively small current though the upper diode capacitance. No need to worry too much about that here as long as the circuit is wired as is.
As another small note, when the circuit is unplugged there is a chance that the cap C1 can stay charged up to 170v or so, so some people connect a 1 megohm resistor across that cap so that it discharges faster. You can do that too if you like but probably dont need it in this app because the circuit is probably not going to be unplugged.