The 4W tape recorder, shown in Fig 16.1, uses silicon transistors in the first three stages to obtain high sensitivity. The output stage uses a complementary matched pair, transistor AD 161npn and AD 162 pnp which are also used for the oscillator during recording. Equalisation is provided for tape speeds of 7½ ips (19.1 cm/s), 3 ¾ ips (9.5 cm/s), 1⅞ ips (4.75 cm/s), and 15/16 ips (2.4 cm/s), which conforms to CCIR Standards where appropriate.

Playback: The BC 109 has been chosen for the input stage because it is particularly suitable for use in audio input stages where low noise is essential. Its collector is directly connected to the base of Q2; its emitter is connected via an RC network to the collector of Q2.. This RC network ...

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