signal injector/tracer

signal injector - tracer be one of the A signal injector must certainly cheapest and most useful pieces of test equipment in the hobby workshop. The design described here doubles as a signal tracer and features an audio output enabling both eyes to be kept on the work in hand. very simple and consists of three The circuit is parts; a signal generator (IC3); a pre-amp mai2n); and a main amplifier. The signal generator, (IC IC3, is a 555 connected as a 1 kHz oscillator. With S2 in position b, this acts as a simple continuity 1 amplify it. In order to detect changes in amplitude, it is im- 9V 100n 6 4 8157 4 LS 1W 10 mV 1N4148 1C1 = LM 386 1C2= CA 3140 1C3 = 171666 DP tester. Since the test points DP are in series with the oscillator"s RC network, the circuit will only oscillate when there is continuity between these points. Two test probes connected to the DP points can therefore be used to establish continuity between two points in the circuit under test. The output of the oscillat...