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555 based SMPS (February 22, 2008)
One of my tasks involved a 105V supply voltage, and therefore a 105V power supply. This simple 555 based switch mode power supply performs nicely around 100 to 300 volts (depending on load) from a 9 to 12 volt supply.
The soul of the supply is a plain 555 driving an N channel MOSFET chopping the current through an inductor. Additionally, the 555's operating frequency (and the output voltage) is regulated by a transistor fed by a voltage-divider on the output section while an R,R,C pole sets the 555 base frequency. A fast schottky diode and a cap complete the output section. In total, the circuit uses 13 components.
From start-up, the supply achieves it's target voltage in about 40ms and quickly stabilizes with some ripple (2-4% at 100mA).
The opening picture shows the power-supply pcb being test-fit as a new kit.
555 (1)
HV (1)
Kit (11)
OnPaper (2)
SingleSided (3)
SMPS (1)
Posted by spiffed at February 22, 2008 4:08 PM