I'm trying to simulate an evening lamp using a NE555 timer and a relay.
To do so, I'm stepping down the 230V AC household voltage to 16V by an RC circuit as shown.
Now, when I take a stand-alone circuit of the rectifier, I get this output. (Output voltage being nearly 170V)
What maybe the reason for this to happen?
Best Answer
First off: No. Stepping down 230VAC using your RC / diode networks there leads to a deadly situation, where, if anything fails, it's likely that you'll have 230V on various parts of the system where the user does not expect it.
In any country of whose regulations I'm aware, such power supplies are forbidden in devices that user might be able to touch any parts of, for good reasons.
A basically unloaded divider can't divide.
What you've built is but a (bit of a strange) bridge rectifier with some smoothing and no regulation, and you load it very lightly. That's not sufficiently close to a constant voltage source. If you loaded it heavily, it would run at a lower voltage, but it would also be very hot, and if your load resistor failed (which would be likely to be the hottest, and thus most likely to fail, component), you'd be back at full 230 V. So, that approach really doesn't work.
You need a proper power supply, and it's really easy to get a safe one these days: You can probably get one for free from someone else's trash bin that gives you e.g. 12 V or 9 V DC, or you can buy (or find) a USB power supply. 5V and a few milliampere would be enough, if you didn't use the ancient NE555. Any CMOS 555 instead of the archaic bipolar NE555 would work with much lower voltages and use much less power!