Basic infra-red transmitter

The transmitter is intended primarilyy for use with the receiver in the preceding article. lt works from two small 1.5 V dry batteries or one 3 V lithium battery. To make the unit compact and yet have reasonable frequency stability, the design uses a phase-shift oscillator, T1, which provides good frequency stability. To ensure that the transistor has sufficient amplification at the low supply voltage, It is a darlington.