In FSK, two discrete frequencies are used to represent the binary digits 0 and 1. The heart of the circuit consists of two Wien-bridge oscillators built using a dual op amp LM 1458, for the two frequencies. The two frequencies are enabled corresponding to....

A low-noise LT1115 (Linear Technology, Inc.) op amp is coupled to a class-A buffer amplifier to produce a variable g..

This circuit uses a comparator as a Schmitt trigger (311H) and two active bandpass filters (LM318H). 3-kHz output ..

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....

Deep discharge can damage a rechargeable battery. By disconnecting the battery from its load, this circuit halts battery discharge at a predetermined level of declining terminal voltage. Transistor Ql acts as the switch...

This circuit has stable threshold characteristics from its dependence on the-photo diode current in the Ll4Cl to generate a base emitter voltage drop across the sensitivity setting resistor. The double phase shift network supplying voltage to the ST-4....

This circuit uses a type 741 op amp as a voltage comparator. One input of the 7.41 is connected to a reference voltage (a 12-V battery) through a resistor voltage divider. The potential at the noninverting input of the 741 is approximately 3 V. The....

This circuit provides a unique solution to a common system-level power distribution problem: When the su..

This circuit outputs a TTL-compatible - pulse whenever the signal falls within the limits set by potentiometers ..

This circuit may be used where a high current is required with a low ripple voltage (such as in a high powered class AB amplifier when high quality reproduction is necessary), Ql, Q2, and R2 may be regarded as a power darlington transistor. ZDl and Rl....

The pulser generates pulses at a user-selected frequency of 0.5 or 500 Hz, with a pulse width of about 5 ms. If the input to be pulsed is already being driven high or low by another output, the pulser automatically pulses the input to the opposite logic....

The circuit is economical in components, and will work with virtually any transistors and is reliably self-starting. The voltage Vb can be taken from a divider, as shown at the right. If taken from a fixed source, flashing becomes slower as battery voltage....

If R, the sensor matching resistor, is equal to the "dark" resistance of the cadmium sulfide cell, the amplifier output will range from 0 to "" 2 as the lightlevel ranges from "dark" to "bright." The circuit in Fig. B operates similarly, but use the....

This low-power inverter uses only 9 parts and turns 10 to 16 Vdc into 60-Hz, 115-V square-wave power to operate ac equipment up to 25 W. The first section of the 556 timer chip is wired as an astable oscillator with R2 and C1 setting the frequency. The....

In the 556 timer, the timing is a function of the charging rate of the external capacitor. For long time delays, expensive capacitors with extremely low leakage are required. The practicality of the components involved limits the time between pulses to....

This circuit uses a low-input-bias op amp to give a steady dc indication of light level. To reduce circuit sensitivity to light, Rl can be reduced, but should not be less than 100 K..

The amplifier operates from supplies ranging up to 12 volts, and operates (with reduced volume) from supply voltages as low as 1.8 volts without having distortion rise to unacceptable levels. (Its power requirements make it suitable for solar-cell....

The laser diode·pulser is a simple drive circuit capable of driving the laser diode with 10-A, 20-ns pulses. For a 0.1 % duty cycle, the repetition rate will be 50 kHz. A complementary emitter follower is used as a driver. Switching speed is determined by....

The sensor circuit is adaptable to different liquids and sensors. The constant-current source drives current through the sensing probe and a fixed resistor..

One preset resistor is used for all the ranges, simplifying the setting up. Diode clamping is included to prevent damage to the meter if the unknown resistor is higher than the range selected..

In this circuit. a negative output voltage de-de converter generates a -5 V output at pin A. In order to generate -5 Vat point A, the primary of the transformer must fly back to a diode drop more negative than -5 V. If the transformer has a tightly coupled....

The indicator flashes an LED when the battery voltage drops below a certain threshold. 2N4274 emitter-base junction serves as a zener which establishes about 6V on the L161"s positive input. As the battery drops, the L161 output goes high. This turns on the....

The circuit is composed of a relaxation oscillator formed by Q1 and an SCR flip-flop formed by Q2 and Q3. With the supply voltage applied to the circuit, the timing capacitor CI charges to the firing point of the PUT, 2 volts plus a diode drop. The output of....

The outputs from the comparators will swing, in sequence, from high to low as the input voltage rises above the reference voltage applied to each comparator. The output LEDs will then switch on in sequence as the voltage rises. The inverting inputs of the....

For multiplying frequencies in the 1-to 150-Hz range, this circuit uses a 4046B and a 100 prescaler. The VCO output..

Because power for the circuit is obtained from the car"s side lights, the circuit can"t oscillate unless the lights are o..

When used as a stand-alone device, ZN1034E from Ferranti can provide timed intervals ranging from 1 second to 19 days, although the rc time constant is only 220 seconds. The ZN1034E includes an internal voltage regulator, an oscillator, and a 12-stage....

The LED is the CSL310L which contains a red LED and a green LED connected back to back and mounted close together in a single moulding. The LED can emit red or^green light by controlling the polarity of the applied voltage and if the polarity is switched at....

CI in series with the crystal may be used to adjust the oscillator output frequency· Value may range between 20 pF and 0.01 µ¥, or may be a trimmer capacitor and will approximately equal the crystal load capacitance. X values are approximate and can vary....

The ratio of capacitors Cl and C2 determines division. With a positive pulse applied to the base of Ql, assume that Cl = C2 and that Cl and C2 are discharged. When {31 turns off, both Cl and C2 charge to 10 volts each through R3. On the next pulse to the....

Ll, Ql, L2, and L3 compose an RF amplifier stage that feeds Ml, a doubly balanced mixer. Q4 is a l..

This simple inexpensive audio amplifier can be constructed using a couple of T0-220 monolithic Darlington transistors for the push-pull output stage. Frequency response is fiat within 1 dB from 30 Hz to 200 kHz with typical harmonic distortion below 0%. The....