Any suggestions for me? I would like to make a bench power supply.
I have this transformer that transform 220V AC to about 10V AC. with rectifier bridge I make DC from it... I use a 2200 uF capacitor to get a steady voltage. the LED and resistor are just there to indicate it's on and to discharge the capacitor when it's off. I then feed it into a voltage regulator (LM317T) to be able to fine tune the voltage.
I am actually thinking of connecting a couple voltage regulators in parallel (connection to point A en B) to provide me with 1V, 3V, 6V and 9V. I also think I should build a current limiter in there. (maybe the easiest way would be a simple fuse)
What I am still struggling with is the value of the smoothing capacitor. 2200uF seems to work... but I am not sure if this is the best choice. I found a general formula for the value of a smoothing capacitor: C = I * t / dV (where t time and dV is the voltage drop to be compensated by the capacitor. In my case it is easy... mains come at 50Hz and the 10V AC as well, so the gap between the peaks is 0.01 second. Voltage drop seems to be around 12 V when I measure it... However, I have no clue what the current is. I tried to measure it using a crappy multimeter (used the 10A socket) and the meter read 19.5 ... I suppose the thing would fuse over 10A ... and it didnt.. so maybe it's 2A? Also not sure if i measured it correctly..basically shortened it with the meter.
anyway... any suggestions are welcome! :)
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