The figure illustrates a reversible de motor drive application with adjustable speed control. The D inputs for these drivers are complementary and can be tied together and driven from the same logic control for bidirectional motor drive. The enables are....

A bridge circuit consisting of two SCRs and two silicon rectifiers furnishes full-wave power to the motor. Diodes, D3 and D5, supply dc to the trigger circuit through dropping resistors, Rl. Phase delay of SCR firing is obtained by charging C2 through....

A four thyristor controlled bridge is used for operation in two quadrants of the torque-speed characteristics. In the trigger circuits the usual pulse transformers were replaced by self biased circuits which minimize gate power consumption and increase noise....

ICl is connected in the astable mode, driving RLA, C3, Dl, and D2 prevent spikes from the relay coil and the wiper motor from triggering ICl. VR2 is adjusted to give the minimum delay time required. VR1 is the main delay control and pro vides a range of from....

Motorola MWA 110, 120, or 130 are wideband amplifier ICs. This wideband preamp circuit can be used in many applications. Keep the leads short when constructing the circuitry. PC board layout (shading represents copper) and parts layout. X is the feedthrough....

This circuit provides a means of detecting the presence of anything by the reflection of infra-red light and provides a direct digital output of object detection. By the use of modulation and high power bursts of infra-red at a very low duty cycle, a....

This is a nice 2 Watts FM transmitter. It has a Super-Sensitive pre-amplification with BC109 and BC177 with more than 100% signal modulation. The job finish the 2N2219 by Motorola. For the Coils you should use 1mm wire(enameled), L1= 3 turns - 10mm diameter,....

The circuit outputs power to the drive motor when one or no sheets are being fed, but interrupts motor power when two or more superimposed sheets pass through the optodetector slot. The optodetector can be either an H2aB darlington interruptor module or an....

A single op amp-one of four contained in the popular LM324-is operating in a variable pulsewidth, free-running squarewave oscillator circuit, with its timed output driving two transistors that control the on/ off cycle of the tape-drive motor. The....

The oscillator is a Motorola MC14410CP chip using a 1-MHz crystal. The chip generates both the high and low tones, feeding the energy to the amplifier through 1-K resistors and the 1-I"F capacitor. Values for the output resistors can vary from a few....

As the speed of an electric drill is decreased by loading, its torque also drops. A compensating speed control like this one puts the oomph back into the motor. When the drill slows down, a back voltage developed across the motor—in series with the SCR....

When the torque load on the motor increases, its current increases. This current increase is sensed across Rs, and positive feedback is applied to the noninverting terminal of the LH0101, thereby increasing the motor voltage to compensate for the increased....

Virtually any NPN small signal transistor may be used in place of the BC 108 shown. Likewise any suitable NPN power transistor can be used in place of the 2N3055. The output transistor must be mounted on a suitable heat-sink. Short circuit protection may be....

This circuit provides a very low cost method of controlling light levels. Circuit power is obtained from a relatively high source impedance transformer or motor windings, normally used to drive the low-voltage lamps used in these functions. It should be....

Connected in this manner, an LM317 1-A adjustable-voltage regulator can be used to control the speed of a miniature dc motor or vary the brilliance of a small lamp. The circuit does so by controlling the pulse width, and therefore the current, to the load....

A 4017 decade counter/divider driven from a low-frequency oscillator (Ul-a and Ul-b) is used to drive transistor switches to sequence the windings, as is needed. MOT1 is a 12-V stepper motor. R9 and RIO are selected for the motor`s current rating. A 3.3-Hz....

In this application, the ICM7249 is configured as an hours-in-use meter and shows how many whole hours of line voltage have been applied. The 20-MD resistor and high-pass filtering allow ac line activation of the SIS input. This configuration, which is....

A shortcoming of the above bi-directional proportional motor control circuit is that with the potentiometer in its center position the motor does not stop, but creeps due to the difficulty in setting the potentiometer for an exact 1:1 mark-space ratio from....

A shot of direct current will instantly stop any ac power tool motor. Switch Si is a center-off, one side spring return. With Si on, ac will be fed to the motor and the motor will run. To brake the motor, simply press Si down and a quick shot of dc will....

This new circuit uses four chips, with an option of using just three (the flip-flops and AND g..

A center-tapped 240-V transformer is used with two SCR devices to provide rectified ac (pulsating dc) to MOT1...

The proximity sensor works on the principle of transmitting a beam of modulated infra-red light from the emitter diode LED2, and receiving reflections from objects passing in front of the beam with a photodiode detector Dl..

The ^generator output is rectified then filtered and applied between the positive supply voltage and the base of the detector transistor. This provides a negative voltage which reduces the base-voltage when the speed increases. In normal operation, if the....

The circuit shown in Fig. 62-15A is designed to drive a 15-V, two-phase, bipolar stepping motor, providing a bidirectional single level voltage across each winding at currents of up to 9.6 A. The circuit consists of two identical transistor bridge stages....

Any dc voltage source in the 2- to 15-V range can be chopped into a unipolar square wave that has a peak amplitude nearly equal to the dc source voltage-with circuit (lightly loaded CMOS will swing within a few millivolts of each rail at low frequencies).....

The speed-control switch offers reasonably good control and stability to both ends of its operating range. This circuit uses two SCR devices in a full-wave configuration to control the dc power to a motor. ..

This frequency/voltage converter enables calibrations of cassette-deck speed. It records a steady 1-kHz ton..

Many countries have 115 volts mains supplies. This can be a problem if your electric shaver is designed for 220/240 volts only. This simple rectifier voltage doubler enables motor driven 240 volt shavers to be operated at full speed from a 115 volt supply.....

By varying either Rl or R2, the oscillator frequency can be adjusted over a narrow range. The R3/R4 ratio sets the second amplifier's gain to compensate for signal attenuation occurring in the phase shifters. The circuits can be driven from an external....

This circuit controls the level of a tank using a bang-bang controlled electrical pump. The actual level of liquid is measured by a capacitive level-meter. The first inverter performs as a capacitance to frequency converter. It is a Schmitt oscillator and....

Using a Motorola MC2833 one-chip FM transmitter, a few support components, and an MPF6660 FET RF amp, this transmitter delivers about 3 W into a 50- load...

The circuit shown here can be used to control the speed and direction of rotation of a series-wound dc motor. Silicon controlled rectifiers Q1-Q4, which are connected in a bridge arrangement, are triggered in diagonal pairs. Which pair is turned on is....