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Silicon
Controlled Rectifier (SCR) Circuits
MINIATURE ISOLATED AC/DC POWER SUPPLY
(3) (acdc1)
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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LOW POWER 12,000-VOLT POWER SUPPLY (55) (12kv)
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. |
CIRCUIT PROTECTS FROM BATTERY POLARITY REVERSAL
(114) (revbat)
This simple circuit can protect a sensitive
electronic circuit from an accidental connection of
a battery with a reversed polarity. The N-channel
FET connects the electronic device to the battery
only when the polarity is correct. The circuit
shown was designed for a device powered from a
single 1.5 volts button cell battery. However, the
circuit will operate with higher voltages as well.
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