Specificaly for the chip that is used in this circuit data are like this: Oscilator runs at freq 200kHz, output noise is below 1% (worst case), max current is 4A at 20V. Voltage can be regulated from 0,0 V (true zero), to 40 V. Voltage and current limit, can be adjusted. You should take special care when purchasing choke. Its ferrite material should be build for frequencies up to 300kHz. Input to the regulator can be DC or AC voltage – becouse the input is rectifier bridge.
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