Published:2011/7/4 23:57:00 Author:Zoey | Keyword: 555 Linear Voltage, Frequency Converter, circuit | From:SeekIC
As shown in the picture5-37, IC1, R1, C1 and D1 constitute an integrator, 555, R2 and C2 constitute a monostable trigger, if input voltage Vi ranges from 0 to 10V, VFC circuit will have a conversion factor of 1kHz/V,which can be converted to frequency of 0~10kHz.
When signal voltage Vin is available, IC1 output will decline, andas soon asit declines to trigger level of IC2(<1/3VDD), 555 will set, VT2 will conduct,D2 and D3 will cease to work, D1 will conduct, VT1 will offer constant current to discharge to C1(If>Iin),output voltage on IC1 output terminal will rise. Then, monostable time capacitor C2 charges, when capacitance reaches to 2/3 VDD threshold level, 555 will reset, VT2 will cease to work, D2 and D3 will conduct, and D1 will cease to work. Therefore, move in cycles, voltage input is converted to oscillation that has various frequencies.
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