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Hope more explaination, what they finally do? why D1?Look at devices 3 and 6. If the output of device 3 is high, it forces the input of device 6 high, and no oscillation can occur. If, however the output of device 3 is low, then theoretically, the output of device 6 is virtually "open" and the oscillator comprised of dev. 5 & 6 is allowed to operate. Now, that portion feeds devices 1 & 2 in an identical manner.
Yes I understand.The circuit posted by the original power beeps when it picks up a high pitched sound.
Yes I understand.The piezo transducer is used both as a microphone and a speaker.
I understand that Tr1 and Tr2 form an amplifier, but how they form a bandpass filter? Can you please explain it.Tr1 and Tr2 form an amplifier and bandpass filter to select the frequency of human whistling.
Is T for the Timer = 1.1 R7*C7 = 1.1* 2.2* 1= 2.4 sec.Gates 3 and 4 form a timer which enable the beeper when triggered by a whistle.
This oscillator freq = 1/(1.4 R8 C8) = 1/(1.4*1*0.001)= 714 HzGates 5 and 6 form a low frequency oscillator which disable the audio oscillator when the output is high.
I need the answer necessaryThank you guru, You already have solved the first problem superbly, I got the idea.
You have mentioned that "The two transistors have three low-value coupling capacitors which are a highpass filter and C6 is a lowpass filter" What are the values recommended by you for the caps to make the circuit better?
To Hero999
Thank you very much for your interest
But you did not answer my question about the diode D1.
I think the voltage at the collector of transistor T2 is a DC voltage + the amplified signal. Those enter the diode, Is the diode passind only the negative part of the amplified signal and blocking both the DC and the +ve part?
thank you