@▷ Voice logic probe by transistor BC557 | Diagram for Schematic

Voice logic probe by transistor BC557

The key is that the logic probe circuit, using a light emitting diode, or LED display is a state (high or low) point of the analysis, but on the other hand, it can display the state has the same voice.
The circuit is shown, it is the audio source, click the tiny speaker with a repetition rate (fast or slow) Is Low status and low costs, high.
The two-transistor circuit (No. BC548 and BC557), the Multi vibrator is a simple astable. One with a 100 kohm resistor and 10 uF capacitor determines the repetition rate, the speaker serves as a load transistor BC557, is in the collection of it Peter, the negative voltage.
BC547 transistor and a resistance of 10 kilo ohms in parallel with a resistor 100 kilo ohms, the Four home inspection when conditions appear to have Carlo Magic high state (high) BC547 will work, the repetition rate increases,.
Designed by Mr. G.. MCLEAN City Gore South Island. New Zealand.

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