Music Logic Test Pen ---- Logic Test Circuits

Keywords: logic test circuit diagram, HY88 The circuit is shown in the figure. Composed of a pair of complementary signal detection control tubes VT1, VT2, and a 8 acoustic music integrated circuit HY-88, using a micro speaker vocal, determined by different music, determined to be measured. Circuit Principle: Circuit. HY-88 is an 8-effective music integrated circuit with PCB (printed circuit board soft package), which has S1 ~ S8 total 8 trigger control terminals, and the low level trigger is valid, corresponding to internal ROM (read-only memory) The 8 kinds of animals stored were called, named, cricket, frog, cuckling, cat, dog, cattle and horseshoes. Adjusting the oscillation resistor R4 can change the sound transfer, the audio signal is enlarged by VT3, and the speaker BL is driven. VD1, VD2 is a step-down diode to make it VDD, and the working voltage between VSS meets 2.5V to 4.5V. The detection state of the logic pen is: (1) When the probe T does not contact the circuit or detects "floating", the VT1 and VT2 are cut off, and the triggers S1, S2 of the IC are respectively pulled to "1" by R3, R2, respectively. , IC does not work, BL silent; (2) When the probe T detects "O", the VT1 is closed, and the VT2 is turned on, S2 is "1", S1 is triggered by "0", BL is emitted; (3) When the probe T detects "1", the VT1 is turned on, the VT2 is cut off, and S1 is "1", S2 is triggered by "0", and the BL is emitted; (4) When the probe T detects "CP" When the pulse is pulsed, VT1, VT2 is turned on, S1, S2 are alternately triggered, and BL produces two kinds of 呜 呜 和 和. Author: Shen Zhi

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