Simple 12-14 Volt DC to 120 Volt AC Inverter
The inverter pictured above uses only four resistors and two transistors, and one transformer. While pictured using NPN transistors, PNP transistors could be used as long as one reverses the battery polarity. I have used both the 2N3055 and TIP41A with R1, R2 at 220 ohms. Make sure the transistors are heat sinked.
Note to use this circuit to create 300 volts for flashtubes use a 12-volt center-tapped transformer. See flashtubes.
The key to the voltage output and frequency is the transformer. To get 120 VAC the transformer will have to be 24-volt center-tapped. If using a 12-volt center-tapped transformer the voltage will be over 240 volts at 14 volts DC input.
This operates by the fact the two transistors won't be exactly alike so they switch each other on/off.
The frequency depends on the physical size of the transformer. Smaller transformers operate at a high frequency, large transformers at low frequency. One small transformer I used (9-volt center-tapped) produced over 300 volts at several thousand Hertz. This operated a four foot fluorescent lamp directly with no other parts. The same circuit with a larger (thus lower frequency output) failed to ionize the lamp.
The frequency will also change depending on the load. Be careful because one can really create some dangerous voltages if mishandled.
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