Newest circuit diagrams

UHF Preamplifier

This circuit is designed to work at UHF frequencies in the range 450-800MHz. It has a gain of around 10dB and is suitable for boosting weak TV signals.

MK484 Radio with Loudspeaker

A complete AM radio set based on the MK484 IC (formerly ZN414).

Programmable LED Flashers

Two simple, wide supply range operating circuits.

Stereo Line Driver

A stereo line driver for feeding long cables or buffering an audio source.

Audio Indicator

This circuit can be used to remotely monitor a loudspeaker, alarm, or audio source for presence of an audio waveform. It can also be directly connected across loudspeaker terminals used as a peak indicator.

Sine Wave Generator

A classic Wien Bridge oscillator using an Op-Amp covering a frequency range of 15 to 150kHz in four switched steps.

Quick on-board Junction Tester

Acoustic check of transistor and diode junctions. Also suitable as continuity tester.

2 Watt Amplifier

A 2 Watt audio amplifier made from discrete components.

Sound Effects Generator 2

This circuit uses the Holtek HT2884 IC to produce 8 different sound effects.

2 Watt Amplifier for 8 ohm load

An audio amplifier made from discrete components with 2 Watts audio power into an 8 ohm load. Carlos has used this amplifier on his AM radio for many years.