To generate regulated ± 5-V supplies from a pair of dry batteries, the circuit of Fig. 1 is commonly used. In order to give protection from inadvertent reverse connection of a battery, a diode in series with each battery would produce an unacceptable voltage drop. The more effective approach is to fit diodes Dl and D2 as shown in Fig. 2, in parallel with each battery. When the supply is switched off, there is the risk of a reverse bias being applied across the.....
This field strength meter consists of a tuned crystal detector producing a dc output voltage from a transmitted signal. The dc voltage is used to shift the frequency of a transmitter of 100-mW power operating at 1650 kHz. The frequency shift is proportional to the received field strength...
Precise, adjustable control of beats per minute from a largo of 18 to a frenzied, high presto of 500, These beats are produced acoustically through a speaker. A light flashes at the same rate. When SW1 is closed, CI begins to charge through Rl and R2. Cl will eventually reach a voltage at which the emitter of unijunction transistor is switched on, "dumping" the energy stored in Cl into an 8 ohm speaker. To produce a distinct "plop", brief pulses across T2 secondary drive.....
This unit is easily tunable and stable, consumes little power, and costs less than other types of oscillators tlmt operate at the same frequencies. This unusual combination of features is made possible by a design concept that includes operation of the transistor well beyond the 3 dB frequency of its currentversus- frequency curve. The concept takes advantage of newly available crystals that resonate at frequencies up to about 1 GHz. ..
The simple diode network can stabilize the voltage supplied to CMOS circuitry from a battery. D1 and D2 must have a c..
A phase-controlled dimmer delays the triac turn-on to a selected point in each successive ac half cycle. Use this circuit only for incandescent lamps, heaters, soldering irons,..
This low-power video transmitter is useful for R/C applications, surveillance, or amateur radio applications. Seven transistors are used in a crystal oscillator-multiplier RF power amplifier chain, and a high-level video modulator. A 9- to 14-Vdc supply is required. ..
The rectifier input is tied to the input. This makes gain inversely proportional to input level so that a 20-dB drop in input level will produce a 20-dB increase in gain. The output will remain fixed at a constant level. The circuit will maintain an output level of 1 dB for an input range of +14 to -43 dB at 1 kHz...
Used for digital control of musical instruments, this transmitter converts the digital data signals to equivalent optical signals for fiberoptic cable interface. Optocoupler IC1 provides isolation, and drives IC2-a and -b and Tl,..
In this circuit, audio fed to the control channel is amplified and rectified by Dl and D2. This dc level activates LED D3 via Q2. The light from D3 causes R9, a light-dependent resistor to decrease resistance. As Rll (audio gain) is set higher, more audio is present at the output of Ql. Audio fed into J2 is shunted to ground via R9 and less of this audio appears at J3...
The circuit consists of two basic circuits, the oscillator and the detector. The oscillator uses an FET in a Colpitts configuration. The energy circulating in the oscillator tank is coupled through C4 to the detector circuit, where a small diode (D2) rectifies it, feeding a dc voltage to the Darlington pair (Q2, A3) controlled by the sensitivity control (R3). Any small variations in the bias of the amplifier will cause large variations of current through the LED indicator.....
At this circuit the SSM2044 IC is used, a 4 pole voltage controlled filter designed for electronic music applications. On-chip voltage control of resonance allows direct and easy interfacing with programmers and controllers. The IC features extended control range, low noise, and high control rejection. The filter can also be used as a low distortion sinewave oscillator...
Ql and Q2 constitute a simple, high-speed FET input buffer. Ql functions as a source follower, with the Q2 current source load setting the drain-source channel current. The LT1010 buffer provides output drive capability for cables or whatever load is required. Normally, this open-loop configuration would be quite drifty because there is no de feedback. The LTC1052 contributes this function to stabilize the circuit. It does this by comparing the filtered circuit output.....
The circuit is built around a 741 general-purpose op amp that is configured as a voltage follower; with the components shown, the op amp has a voltage gain of one. The output of the 741 is used to drive a 50- meter movement. Potentiometer R7 is used to zero the meter and R6 sets the meter`s full-scale reading, Calibrating the meter is a snap. With no input applied to the circuit, set R6 to mid-position and adjust R7 to zero the meter. Once that is done, apply a positive.....
This circuit has read the RIAA equalization, tone controls, and adequate gain to drive most power amplifiers conunercial by using CA3410 op amp BiMOS. Total harmonic distortion, pushed to provide an output of 6-V, is less than 0.035% in audio-frequency range from 150 Hz to 40 kHz. ..
The logic input is applied to opto-isolators Ul and U2 with, respectively, npn and pnp emitter follower outputs. Dc balance is adjusted by potentiometer R2. The emitter followers drive the gates of Ql and Q2, the complementary TMOS pairs. With a ±12 V supply, the swing at the common source output point is about 12 V peak-to-peak. By adding a ± 18-V boost circuit, as shown, the output swing can approach the rail swing. ..
The positive and negative peak amplitude is controllable to an accuracy of about ± 0.01 V by a dc input. Also, the output frequency and symmetry are easily adjustable. The oscillator consists of an integrator and two comparators—one comparator sets the positive peak and the other the negative peak of the triangle wave. If R1 is replaced by a potentiometer, the frequency can be varied over at least a 10 to 1 range without affecting amplitude. Symmetry is also.....
This circuit monitors the power-line (ac) voltage. When a power failure occurs, on restoration of power, the circuit a..
This electronic music maker uses an astable oscillator circuit that is controlled by a photocell. The light falling ..
A gas sensor (TGS823 from Allegro Electronics, Cornwall Bridge, CT 06754) conducts in the presence of explosive gases. U5 is a voltage-to- frequency converter that produces a frequency proportional to the sensor conductance. The output frequency ranges from 100 IIz in clean air to 8 kHz in a contaminated atmosphere. The dc voltage from the sensor also drives bar graph LED U7 and comparators U4-b and U4-c to sense present caution and danger levels. ..
Operational Amplifiers
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