Frequency logic pen ----- Logic Test Circuits

Keywords: CD4093, logic test circuit The circuit is shown in the figure. Composed of four two outputs with non-doors, one transistor, and vocalizing the piezoelectric ceramic buzzer, determined by the tone differently. Circuit Principle: The circuit is composed of "0" oscillator with non-door ICB, R3, C1, composed of non-door ICC, H4, C2, and the oscillator, oscillator, oscillator, oscillator The frequency is also different. The 7 feet of the ICB 5 feet and ICC are the control terminal, and the oscillator is operated when the level is "1", and the rectangular wave is output. The detection state of the logic pen is: (1) When the probe T does not detect or detect the "floating" state, the I-CA output "0" (generally when the logic gate input is opened, the input is "1"). At the same time, VT is closed, and the 7 foot of the ICC is pulled "0", "0" oscillator and "1" oscillator, and the buzzer HTD does not sound: (2) When the probe T is detected When "0", the VT is closed, the ICC's 7 foot is "0", "1 '' oscillator does not work. At the same time," 0 "signal is" 1 "," 1 "," 0 " "The oscillator has a rectangular wave oscillation signal that produces lower frequencies (preferably 200 Hz ~ 600 Hz), and the ICD drive HTD will issue a low frequency sound; (3) When the probe T detects" 1 "time, the ICA is reversed The 5th foot of the ICB is "0", "0" oscillator does not work, at this time, the VT is turned on, the 7 foot of the ICC is "1", "1" oscillator, oscillating with 1000 Hz-1500Hz. Signal, via ICD drive HTD to issue high-frequency sound: (4) When the probe T is detected, it is equivalent to "0", "1" alternate input, "0" oscillator and "1" oscillator turntable HTD produces high and low frequencies. Component selection: ICA-ICD uses two inputs with Schmitt trigger and non-door integrated circuit CD4093, which contains four two inputs and non-doors, so it can Satisfied. VT is used to select 3DG8D. Take β = 80 to 120, HTD uses a 27A-1 piezoelectric buzzer, + 5V, GND in the figure, and the power and ground of the circuitry circuit. Author: Shen Zhi

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