Pulse Width (PWM) Controller Circuit

A LM3900 quad operational amplifier can be used to build a pulse width (PWM) controller. The LM3900 was chosen because it only need single supply voltage of 4 to 30 V. This circuit can give 100 percent pulse-width control.  A1 op-amp forms a 1 kHz oscillator, generating a square wave oscillator for the basic oscillation. A2 is a ramp generator […]

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Flash-Triggered Pulse Stretcher Using Classic Monostable Circuit

This is a flash triggered (photo-driven) circuit which produce a pulse with constant predetermined wide. This circuit can be used to control any device which is required to be synchronized with optical trigger/flash light.  The pulse can be used to drive relay (after proper power buffering,  to drive other circuit logic, or electronic switch.  We call it a pulse stretcher […]

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