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hobby electronics circuits

hobby electronics circuits

2-transistor circuit RadioShack "learning laboratory" - I would like more information.?

Ive been going through the book included in a pastime of the RadioShack electronics, kit, and the kit does not do a good job of explaining how the circuit really works. Ive received an image circuit http://www.grandpizzaarmy.com/flash/circuit.jpg This circuit makes the sound of cicadas (on and off several times) at an interval that is modulated potentiometer. I handled this circuit on my breadboard, and it works, but I'm terribly confused about what exactly happens with the capacitor label C1. My specific questions are: How and when (T1 + T2 state) charges C1? In what way (s) C1 not download? When Q1 and Q2 are off, C1 is connected to the opposite, an explosion C1 why not? In addition, any response to a report by explaining how the State does the circuit would be greatly appreciated

Because the emitter of Q1 goes directly to 9V. supply, extreme left of C1 can not go below 8.4V, so the capacitor voltage does not reverse, or not much. When power is applied, Q1 is turned on, which turns on Q2. This positions C1 through the base-emitter of Q1 and R3. When the capacitor is charged, the current begins to decrease, thus increasing voltage on the collector of Q2. This is transferred to the base of Q1 and sets off a chain reaction in the other direction, that turns off both transistors. Now the end of C1 + is about 18V., Y begins to download, for 1M and 100K resistors. In fact, you can pay part of what saves time by the 1K resistor and the BE junction, most transistors have a reverse breakdown under 10V. The resistance of 1K to avoid damaging transistor. When the capacitor voltage rises to near zero (9V to + end), Q1 begins to conduct again and the cycle begins again. The cycle time is probably a little less than one time constant (R * C = 47 to 5.17 seconds).

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