Hi. Please take a look at this circuit here:
This is from a toy/ornament that connects to one node of a xmas light string and shows 4 mini lamps through some colored plastic lenses.
It measures about 11.2V AC at its inputs when connected. Furthermore, each of the 4 mini lamps seem to have a 2.35V DC drop across them. I just want to understand what those Zener Diodes do exactly? I don't have the codes of which type they are (maybe IN4148 switching diodes?). Can I assume that they are just there to lower the voltage that the lamps see by 1V or so? Finally, with a multi-meter how can I measure the current that this circuit is drawing?
Also, if I apply a 12V DC source to those AC labelled inputs, it seems that it is too much since the Zener diodes get really hot and I start smelling a slight bit of smoke smell. Why is that?
And finally, I want to do the following. I want to take say a 20V DC source and attach to this to make it work (without burning the lamps prematurely). Hence, I guess I should first get rid of the 4 bottom diode/bridge (IN4005 I believe). Then, can put a resistor in series (1/4 W or 1/2 W and where in this circuit) so that I can bring the 20V DC down to about say 8V DC to run this? I imagine that if I had how many AMPS the circuit draws, I can then use OHMs lamp to calculate the R value needed to lower the voltage for this.
Thanks for any input/education you more advanced electronic guys can provide to me.