Scope calibrator

Off-line flyback regulator

This circuit uses a low-cost feedback scheme in which the dc voltage developed from the primary-side control winding is sensed by the UC1842 error amplifier. Load regulation is therefore dependent on the jcoupling between secondary and control windings, and on transformer leakage inductance.

Optical-sensor-to-ttl-interface

This circuit is designed to detect a low light level at the sensor, amplify the signal, and provide a TTLlevet output. When the optical sensor detects low-levellight, on condition, its output is small and must be amplified. An amp with very low input bias current and high input resistance must...

Stabilized-amplifier

This amplifier functions over a wide range of gains, typically 1-10. It combines the LT1010 and a fast discrete stage with an LT1008 based de stabilizing loop. Q1 and Q2 form a differential stage which single-ends into the LT1010. The circuit delivers 1 V pk-pk into a typical 75-0 video load. At...

Window-detector

This circuit de-energizes a normally energized relay if the input voltage goes above or below two individually set voltages. The transistor driving the relay is normally turned on by R4, so the relay is normally energized. Ifthe cathode of Dl or D2 is taken negative, Ql will turn off and the...

Metal Detector

An NE602 acts as a heterodyne detector and Ql as a sense oscillator. When Ll is brought near metal, it causes a charge in lo

Simple Ring Detector

This circuit detects the 20-Hz approximately 86-Vrms ring signal on telephone lines and initiates action in an electri

Simple Coil-less AM receiver

This AM receiver is working perfectly without the need of coils or even a variable capacitor. The LF356 is the basic component. P1 and P2 are the frequency selectors. Use a small telescopic antenna. The stations selectivity is not perfect but is acceptable.

Delayed headlights circuit

This circuit keeps an automobile's headlights on temporarily. It also will turn the lights off, even if you forget to flip the light switch. The circuit's shut-off delay is actuated only after both the ignition and light switches have been on, and only if the ignition switch is turned off first....