Many Inverter Circuits have already been posted in many other website. The inverter circuit “Crystal Controlled Inverter“ presented here provides a stable output frequency even when there is change in the DC voltage applied to the inverter. This stable output of Crystal control Inverter is obtained from the 3.2786 MHZ crystal (XTAL1).
Circuit Description of Crystal Controlled Inverter.
The Inverter circuit “Crystal Controlled Inverter“ is build around popular flip flop IC MM 5369 (IC1) followed by few other active and passive components. IC1 (MM 5369) contains 16 cascade flip flop, which divide the input frequency 3.2786 MHZ by factor of 216. Thus we get an output frequency i.e. 3,276,800 Hz/216=50 Hz.
The frequency of 50 Hz is available in the pin 1 i.e. at output of IC1 (MM 5369). The timer capacitor is used to adjust resonant frequency of the crystal. The CMOS chip (MM 5369) cannot deliver or sink more than 10 mA, therefore a current amplifier is necessary to drive the driver or pre-driver stage of the Crystal Control Inverter.
The fundamental mode of crystal is 3.2768 MHZ, and operates in this mode. The small changing in the frequency of oscillation of crystal in Crystal Controlled Inverter is caused by trimmer C2. The trimmer C2 is also used to adjustment of damping in the network. C1 is also used to balance the network as trimmer C2 do. Resistors R1 is used as load and R2 is used to limit the current flowing through the chip. In the event of reversal of polarity at the battery terminal diode D1 serves as protector of the IC1 (MM 5396).
Resistors R3, R4, and R5 is used as current splitter to share current in base of transistor drive from the chip. For total inversion of 3600 and 00 transistor T1 and T2 is used as inverter. Transistor T3 is also connected as an inverter and the output at the collector of T3 is at a phase difference of 1800 with respect to the signal at the collector of transistor T2. Transistor T4 & T6, T7 & T8 and T5 & T9, T10 & T11 are connected as Darlington pair configuration as shown in circuit diagram of Crystal Controlled Inverter. The advantage of this type of configuration in Inverter Circuits is, it provide enough base drive for the power stage flows through the transformer which is connected of T4 and T5. This also increases efficiency of the Inverter, because in this configuration, additional current flows through the transformer rather than through resistor and dissipated as heat in them. The excessive PIV generated in the transformer due to the switching action of the power transistor is protected by diodes D2 and D3.