Portable TV black and white striped generator ----- TV Signal Generator

Portable TV black and white stripe generator, TV Signal Generator Keywords: TV black and white striped generator Television black and white stripe generator Here is a television black and white stripe generator composed of digital integrated circuit CD40106 and triode BC547, and audio signals. The generator has two outputs, one is a video black and white stripe, and its second is a sound output. When using, simply use the video output of the generator with the video input of the television through the video cable connection; the audio signal is connected to the television connected to the TV. If the TV is working properly, you can see the black and white stripes on the TV screen and issue an audio sound, so the generator can be used to calibrate the time-strike (time base) circuit of the fault TV, field (vertical) ) Synchronous circuits and sound circuits. Circuit Working Principle: Circuit See Figure CD40106 is a 6 Schmitt Trigger, wherein the door inverter A1 consists of the peripheral circuit D1, D2, VR1, VR2, and C1, a horizontal synchronous pulse oscillator, adjusting VR1. The synchronous pulse width (high) is close to 60 μs; adjusting VR2, so that the low level time of the synchronous pulse is 4.71 μs, that is, the row synchronous pulse period is 641 μs (PAL system). The door inverter A2 in the drawing forms a synchronous pulse and the post-stage buffer, the door inverter A3-A5, and the peripheral circuit completes the following functions of the video signal: adjust the potentiometer VR3, which can control the vertical of the television black and white stripes. Start position; adjust VR4, can control the end position of black and white stripes; adjust VR5, control the width and number of vertical lines. Once the generator is calibrated by the above-described method, it is possible to detect the partial fault (traveling field) of other televisions. If the reader does not signal the synchronous pulse waveform during the above debugging, VR1 and VR2 can be used to obtain a fixed resistor 150kΩ and 22kΩ, or the A1 oscillator can result in the desired synchronous pulse line frequency 15625Hz. Now there is a digital multimeter displayed in the electronic market, which can directly test the frequency (up to 10MHz) and duty ratio of the pulse, which can directly test the frequency and duty cycle of the A1 oscillator to correct adjustment. The resistance of the above fixed resistance. The triode V in the circuit constitutes a video signal of the emitter outputter as a video output signal of the generator. The middle door inverters A6 and R5, C5 constitute an audio oscillator (FO ≈ 800 Hz), reappearing the coupling output by R6 and C6, and is used to detect whether the sound channel of the television is normal:

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