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Circuits Designed by Dave Johnson, P.E. : |
- 18v AC to DC Power Supply
This is a classic linear power supply which produces a regulated 18v, rated at about 1 amp. (added 7/06)
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- 240VAC TO 5VDC POWER SUPPLY
This is simple way to power some 5v logic from a 240vac source. If a 120vac power adapter is used, the circuit will also work for 120vac power lines.
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- CAPS PROVIDE VOLTAGE BOOST TO SERIES REGULATOR
This circuit adds some capacitors and diodes to a traditional transformer type series regulator circuit to extend the normal operating range. It can insure regulation during low line voltage conditions or it can squeeze a few more watts out of a plug-in-the-wall power
adapter power supply.
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- LOW POWER 12,000 VOLT POWER SUPPLY
If you need about 12,000 volts DC for an ion generator this circuit might be the ticket. It draws power from the 120vac power line but it uses a small 6KV camera flash trigger coil. The output signal is isolated from the power line. Although the circuit can only deliver
about 5uA of current it can produce dangerous shocks, so be careful.
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- MINIATURE ISOLATED AC/DC POWER SUPPLY
This circuit uses a novel approach to produce a fully isolated and regulated 5 volts @30ma from the 120vac power line. It uses two tiny SCRs that alternately discharge two capacitors through a miniature high frequency transformer. The voltage spikes produced through the
transformer are rectified, filtered and regulated. A very common 8 ohm audio impedance matching transformer can be used for the transformer. Published in EDN, Feb. 17, 1992
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