LM2907 Motor Speed Control – Part 1

We can purchase DC motors with or without brushes with ac tachometer outputs already provided by the manufacturer. A very low cost speed control can be constructed with these motors in combination with the LM2907. The most simple version is illustrated in figure below where the tachometer drives the non inverting input of the comparator up towards the preset reference […]

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LM2907 Motor Speed Control – Part 2

The following figure show us an alternative approach which gives proportional control. The charge pump integrator is shown in a feedback connection around the operational amplifier. For zero speed, the output voltage is equal to the reference voltage set up on the potentiometer on the non inverting input. The charge pump puts charge into capacitor C2 and causes the output […]

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555 Infrared Transmitter-Receiver

Infrared transmitter and receiver circuit shown in the schematic diagram below can be used as remote control. The transmitter is basically an oscillator circuit, and the frequency can be adjusted using R1 potentiometer (or trimmer pot). This oscillation makes sure if the signal can be distinguished from other source by the receiver. The receiver is actually a bandpass filter which […]

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