Simple FM transmitter (CB8728E)

Found in 90s Radio Electronics, this small transmitter has a good range. L1 is formed by 3 + 3 turns of wire 24 around a pencil as a reference.

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Dual Temperature Control (CB15791E)
This circuit controls two relays from a single temperature sensor. The first fires when the...
TDA2020 Amplifier (CB4357E)
This integrated amplifier was found in an English magazine that no longer exists, from 1975. The...
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In the figure we have the way of obtaining 220 V from two equal 110 V transformers or 230 V from...