Hi,
Can someone help me understand how this circuit works? It is for a night light which plugs into a wall outlet and is supposed to come on in the dark, and it’s not working.
I believe I have traced it accurately and have checked 3 times, but it just seems wrong! I can attach pictures of the actual circuit board (both sides) if it would help.
I would expect that after the bridge rectifier I should have 120x1.414 = 170V DC. This then goes straight to the lamp, which seems crazy high, plus then what is the purpose of the rest of the circuit? And I am measuring only 105V DC at the lamp. The lamp itself is burnt out and I suspect that it is a low voltage (and of course low wattage) lamp that got zapped by high voltage.
Here are a few questions:
Thanks, I would really appreciate any insights.
Can someone help me understand how this circuit works? It is for a night light which plugs into a wall outlet and is supposed to come on in the dark, and it’s not working.
I believe I have traced it accurately and have checked 3 times, but it just seems wrong! I can attach pictures of the actual circuit board (both sides) if it would help.
I would expect that after the bridge rectifier I should have 120x1.414 = 170V DC. This then goes straight to the lamp, which seems crazy high, plus then what is the purpose of the rest of the circuit? And I am measuring only 105V DC at the lamp. The lamp itself is burnt out and I suspect that it is a low voltage (and of course low wattage) lamp that got zapped by high voltage.
Here are a few questions:
- What is the purpose of R1 and C1?
- R4 is burnt (open) and the markings are also burnt. I assume the circuit failure is because R4 has burnt out. What would be the appropriate value here, assuming that the output to the lamp should probably be 12 volts DC max, and most likely lower, maybe 3 to 6 volts. There are no markings visible on the lamp to help determine its rating.
- How does this circuit control (step down) the voltage to the lamp, the way it is drawn? Or, if I have drawn it incorrectly what is the more likely way it should be drawn?
Thanks, I would really appreciate any insights.