Simple logarithmic amplifier circuit

Filtered-sample-and-hold

Itis often required that a signal be filtered prior to sampling. This can be accomplished with only one device. Use any of the inverting and noninverting filters that can be built with op amps.

AC-static SPDT switch

An SPDT solid state relay is shown. When voltage is applied Ql will turn on, activating load #1, because the full line voltage appears across Q2, supplying gate current through Rl. When SI is closed.

Current Loop

This 5-V circuit utilizes a servo-controlled dc/dc converter to generate the compliance voltage necessary for loop-

Analog Tachometer Readout

The analog display consists of a frequency/voltage converter (IC12) and bar-graph segment drivers IC10 and IC11.

Audio Compressor Circuit

This compressor will compress a 25-mV p-p to 20-V p-p audio output to input levels remaining between 1.5 V p-p to 3.5 V p-p, and has a frequency response of 7 Hz to 67 kHz.

Twang-twang circuit

Twang is a guitar sound that more or less approximates a banjo or mandolin. The circuit produces unusual sounds from an ordinary electric guitar by cutting the bass, severely distorting the midband and highs, and then amplifying the distortion.

Tv-transmitter

This transmitter is capable of two levels of rf power. For low-power wireless video, like in a house or office, where simultaneous monitoring of program material is desirable without cumbersome hookups, 1-30 mW is available. For longer ranges up to several miles, as in amateur (ham) TV,...

Optical communication system

The circuit will modulate the light from the LED using a crystal microphone or a loudspeaker output. To obtain the maximum range, the optical system must be efficient (see example). Either a convex lens or a concave mirror can be used to convert the LED output into a parallel beam. The received...