The circuit can be used to give a visible or an audible warning that the headlights are on. It uses a 2N1305 ..

The microprocessor-controlled oscillator has a 8159 to 1 frequency range covering 2 Hz to 20 kHz. An exponential, current output IC DAC functioning as a programmable current source alternately charges and discharges a capacitor between precisely-controlled....

You can turn any ordinary household bulb into one that shimmers or blinks. This circuit works on any incandescent light up to 200 W, arid runs on standard 120 Vac. The circuit uses an SCR to cause an ordinary lamp to sliimmer. Note that one side of the lamp....

This alternator regulator uses a 3-transistor dc amplifier, and is designed for a pulled up field system, where one side of the alternate field returns to the +12-Vsupply, and the other end is pulled toward ground...

The resistor capacitor network R1-R2-C1 provides a ramp-type reference voltage superimposed on top of a dc voltage adjustable with the speed-setting potentiometer R2. This reference voltage appearing at the wiper of R2 is balanced against the residual....

The LM39X4 acts as a LED-driving vol-tometer that has its basic maximum and minimum readings determined by the values of R2 and RV2. When correctly adjusted, the unit actually covers the 2 volt to 3 volt range, but it is made to read a supply voltage span of....

The input voltage, V1, causes C1 to charge and produce a ramp voltage at the output of the 741 op amp. Diodes D1 and D2 are four-layer devices. When the voltage across C1 reaches the breakover voltage of either diode, the diode conducts to discharge C1....

When long ranges must be worked with IR light sources, and when high system reliability is required, pulsed-mode operation of the IRis required. Additional reliability of operation is attained by synchronously detecting the photodetector current, as this....

An audio signal applied to VI is passed through the operational amplifier 741, U2. After being amplified, the output signal V2 is sampled and applied to a negative voltage doubler / rectifier circuit composed of diodes CRI and CR2, with the capacitor C1. The....

This circuit provides interferenced rejection for the CW operator. The 567 phase-locked loop is configured to respond to tones from 500 to 1100 Hz. The Schmitt trigger reduces the weighting effect caused by the output of the PLL remaining low after removal....

A high-frequency audio signal (15 to 25 kHz) generated by Ul is fed to buffer Ql and SPKR1. A portion is f..

The circuit provides a windshield wiper delay, dynamic braking and windshield wipers when they reach the rest position. This prevents the blades passing, which could lead them to stop at a point where they interfere with the vision of drivers. With the....

The low Rds and high peak current capability ofthe DG419 makes it ideal for discharging an·integrator capacitor. A high logic input pulse disconnects the integrator from the analog input and discharges the capacitor. ..

A clever charger circuit that safely can charge any Ni-Cd battery. Offers charge current sellection, polarization detection and protection and the ability to connect many batterys in siries. Ni-Cd bateries can be recharged more than 1000 times before become....

An LM556 dual oscillator/timer, U1, configured as a two-tone oscillator drives U2, a dual4-watt amplifier. One of the oscillators, pins 1 to 6, contained in U1 produces the upper frequency signal of about 200 Hz, while the second oscillator, pins 8 to 13,....

Temperature control is achieved using the REF-02 +5 V Reference/Thermometer and a CMP-02 Precision Low Input Current Comparator. The CMP-02 turns on a heating element driver (Ql) whenever the present temperature drops below a setpoint temperature determined....

This circuit has a 100 mV hysteresis which can be used in applications where very fast transition times are required at the output even though the signal is very slow. The hysteresis loop also reduces false triggering due to noise on the input..

This self-starting fixed-frequency oscillator circuit gives excellent frequency stability. R1 and C 1 comprise the frequency-determining network, while R2 provides the regenerative feedback. Diode D 1 enhances the stability by compensating for the....

The NE564 is used as an FM demodulator. The connections for operation at 5 V and 12 V are shown in Figures 21-4A and 21-4B. The input signal is ac coupled with the output signal being extracted at Pin 14. Loop filtering is provided by the capacitors at Pins....

This circuit is meant to be driven by a 1-MHz standard signal of a few volts amplitude. Ul through U5 are 7490 decade counter/divider and produce a division ratio of 100,000:1. Successive divisions of 10 can be tapped off, if desired, between stages. ..

In this application, the timer is connected in the monostable mode. The circuit is triggered with a continuous pulse train and the threshold voltage is modulated by the signal applied to the control voltage terminal at pin 5. This has the effect of....

This 2-band compressor splits the audio into high and low frequencies and allows independent adjustmen..

To obtain a 1000:1 Sweep Range, the voltage across external resistors Ra and Rb must decrease to nearly zero. This requires that the highest voltage on control pin 8 exceed the voltage at the top of Ra and Rb by a few hundred millivolts. The circuit achieves....

This circuit is for low voltage applications requiring high power outputs. Output power levels of LO W into 4 ohm from 6 V and 3 V into 8 ohm from 12 V are typical. Coupling capacitors are not necessary since the output dc levels will-be within a few tenths....

This circuit offers 10- to 15-dB gain from 400 to 850 MHz and is therefore eminently suitable for situations where th..

An op-amp comparator is used to compare the converter output with a dc threshold voltage. The circuit flashes the LED when the input frequency exceeds 100 Hz. Increases in frequency raise the average current out of terminal 3 so that frequencies above 100 Hz....

The solar cell is connected across the input of the FET (field-effect transistor), Ql, so that it will produce positive dc voltage to the gate when activated by light shining through the open shutter, decreasing the negative gate-source bias already....

The circuit will operate reliably from below 1 MHz to above 400 MHz. With Vcc = 5 V the output of the second inverter essentially attains a full swing from 0 V to 5 V. Such large logic output levels and broad frequency range capabilities make this oscillator....

This de adapter provides a regulated 9-V source for operating a Kenwood TR-2500 hand-held transceiver in the car. The LM317T"s mounting tab is electrically connected to its output pin, so take this into account as you construct your version of the adapter. ..

Most circuits that provide an electrical stimulus for research subjects are constant-voltage designs; this circuit is a constant-current design. Stimulator circuits must be isolated for two reasons: to ensure safety and to minimize interference. Isolated....

The modified power-factor controller, developed at the Marshall Space Flight Center, employs a phase detector for each of the three phase windings of a delta-connected induction motor. The phase-difference sum is the basis for control. ..

This simple circuit generates both white and pin noise. Transistor Q1 is used as a zener diode. The normal base-emitter junction is reverse-biased and goes into zener breakdown at about 7 to 8 volts. The zener noise current from Q G flows into the base of Q2....