60W inverter using transistors

Description.Here is thecircuit diagramof a fully transistorizedinverterthat can drive up to 60W loads. Transistors Q1 and Q2 forms a 50Hz astable multivibrator. The output from the collector of Q2 is connected to the input of the Darlington pair formed by Q3 and Q4.Similarly the output of Q1 is coupled to the input of the pair Q5 and Q6. The output from the Darlington pairs drive the final output transistors Q7 and Q8 which are wired in the push pull configuration to drive the output transformer.Circuitdiagram.

T1 can be a 230V primary to 9-0-9V, 6A secondary transformer. TransistorsQ4, Q6, Q7 and Q8 must be fitted withheat sinks. Use a 12V, 7Ahbatteryfor powering the inverter. Slight adjustments can be made on the value of R3 and R4 to get exact 50Hz

Inverter Design Tips.The maximum allowed output power of an inverter depends on two factors.The maximum current rating of the transformer primary and the current rating of the driving transistors.For example ,to get a 100 Watt output using 12 V car battery the primary current will be ~8A ,(100/12) because P=VxI.So the primary of transformer must be rated above 8A.Also here ,each final driver transistors must be rated above 4A. Here two will be conducting parallel in each half cycle, so I=8/2 = 4A .These are only rough calculations and enough for this circuit.