Diagram of Precise Timer composed by LM567 and MP1826

Published:2011/8/9 18:00:00 Author:Vicky | Keyword: Precise Timer | From:SeekIC

LM567 is a frequency demodulating circuit. The circuit uses it as a two-frequency oscillator to generate the low-frequency pulse required by MP1826. The frequency of the central oscillating ƒ0 is determined by C1, R2 and R3. ƒ0 is output by 3 pin of LM567, and 2 ƒ0 output by 8 pin can change the time constant of the circuit. ƒ0 varies between 0.01Hz to 500kHz. In this circuit, ƒ0 is 4Hz. When the circuit is on, MP1826 firstly reset, and meanwhile D1 go out after twinkling several times. In the low-frequency pulse input MP1826, pin 10 changes to high level after T time, and pin 11 changes to high level while pin 10 changes to low level after another T2 time; pins from 12 to 17 work in the same manner. When the pin 8 is grounding, pin 24 changes to high level after a period of time of 105×T2. Then the timing of the circuit ends. If the parameters of the components remain unchanged, there are 18 grades of timing of the circuit.



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