I want n 12V 1A supply for a project. I want a transformer-less topology.
I was reading and experimenting with readily available traic based dimmers. They use phase control to cut the input voltage to a load. So I thought it might be used to provide a stepped down voltage.
Here's what I have done so far:
- Connected a simple dimmer to the phase line, set it to minimum (which is about 20% I guess), rectified it and connected a filtering capacitor to the positive and negative terminals of the bridge. The output voltage was still 220v.
- Next, I connected a 10k resistor to the between the positive and negative terminals. The voltage dropped significantly.
Now, the the output voltage was dependant on two things.
- The output voltage increased as I increased the phase from the dimmer which was as expected.
- The output voltage also depended in the load resistor. If I increase the load resistor, the output voltage increased. Now, this was something that I think will cause problems depending on the type of load I connect in the future.
The scope of the project is not just limited to the 12W requirement. Ih I can convert 220vac to 30vdc, then I can connect a buck-converter to this and use it as a variable power supply.
Please help me complete this.