Monday, 16 December 2019

capacitor - Understanding LED driver circuit AC to DC conversion


I am recently working on mains socket outlet type LEDs lights. They all have very similar AC to DC conversion circuit.


schematic


simulate this circuit – Schematic created using CircuitLab




  1. C1 is a X-2 type capacitor and I know it has Independence $$X_c= \frac{1}{2\pi fC} \approx 9.6 k\Omega$$ Thus, the AC current will be limited by this cap at 230/9.6k=23mA. But what the R1 does in the circuit?




  2. R2 is a big through hole resistor, does it act like a fuse or something?





  3. D1 is a Zener diode. I guess it is here to regulator the voltage to its breakdown voltage, like 5V or 12V. Am I right?




  4. This circuit doesn't have a transformer like 230V to 12v before the rectifier, would it be safe in practice?




Thanks a lot!




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