Author: Huang Bo
Quartz crystal oscillator referred to as "crystal", which is widely used in electronic clock, walkie-talkie, single chip microcomputer, color TV color-visual oscillation frequency division circuit and all infrared remote controls. For the determination of crystal and bad, it is generally only determined whether or not the electricity, short circuit, or the two-legged capacitance values of its two-legged, and the rough estimate of it is very bad, and the frequency offset it has fallen, and the default is not measured. The instrument of the test crystal frequency is high, difficult to buy, and low utilization rate. In fact, you can do it homemade, the cost of material is only 10 yuan (with a color TV remote control, another small circuit board), the material is ready for half an hour, and it can be accurate with the digital frequency meter. Measure the remote control crystal crystal frequency and determination the remote control. The modification method is as follows: Disassemble the rear cover of the remote control, 455 kHz crystal on the board. Take a test clip with a double-column 8 foot IC, only single colony, 1 ~ 2, 3 ~ 4 foot is welded to the board to do a crystal detection clip, and the purpose is to facilitate the plug of different sizes. The frequency meter test is welded with the crystal test clamping with the crystal test. The test clamp is welded to the remote controller, and the 3V power supply on the remote control is used to another circuit. The board is powered, and the additional small piece circuit board is connected to the 5 line (2 power 2 test) to the remote control, the other line is output by the R2 remote control IC (ie the NPN triode B pole on the remote control), The crystalline exclusion is inserted on the test clip socket, press the remote control button, and the LED is shining. If the digital frequency meter can accurately measure the remote control crystal crystal frequency.
Other remote controls the infrared photosensitive diode button, the light emitting diode will shine, indicating that the remote control is good. The color TV remote control IC model is Mitsubishi M50560-001P. The crystallized vibration is 2 100PF capacitance, and the frequency is measured by Victory VC920 pocket digital multimeter, and the frequency range is 0 ~ 20MHz. Experiments have proven: the trap, the three-shot oscillator can increase, 1MHz or less crystal can be accurately measured using the multimeter measurement function, and the multimeter measuring table measured by a crystal vibration of the large-end 1MHz. The crystal is inserted into the remote control, and D2 in the figure below will still be emitted. The color TV remote control is similar, like working principle, as long as the crystal frequency is less than 7.15 MHz. Other models of color TV remote control can also be made such as a method. The circuit is shown below. The circuit is very simple, 2 NPN triode composition composite tube is used to enlarge the detected remote control infrared optical signal, D1 with a flat infrared light-emitting diode, D2 red circular light emitting diode, R1 is D2 current limiting resistance, R2 is remote control On the IC output current limiting resistor, the R3 and DL constitute a voltage dividing circuit object is to vent the reverse penetration current of the DL. If there is no R3, D2 will be bright. Resistors can be used 1 / 8W.
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