PURPOSE: To improve the efficiency of an inverter circuit by oscillating the bases of two push-pull connected transistors by positively feeding back currents to the bases through two parallel CR circuits having suitable electric-discharge time constants from the collector coils of the transistors facing each other by alternately driving a transformer with the transistors.
CONSTITUTION: A push-pull type inverter circuit is constituted of transistors Tr1 and Tr2 and collector coils 9 and 10 of a transformer 8. The inverter circuit is provided with bias resistors 3 and 4 and bias capacitors 5 and 6 and the capacitors 5 and 6 are respectively connected in parallel with resistors 3 and 4. The two parallel circuits are connected between the bases and collectors of the transistors Tr1 and Tr2 in a crossing state and make a positive feedback current to flow to the bases of the transistors Tr1 and Tr2 to excite the bases. When the CR time constants of the two parallel circuits are adjusted, the phase and conducting waveform of a base bias current are adjusted and the waveform becomes a sine wave. Therefore, a simple inverter circuit which is less in power loss and suitable for a capacitive fluorescent lamp load, etc., can be obtained.
YAMADA KAZUO
YAMAZAKI HIROSHI
