Bench AF Amplifier. Schematic Diagram.
The circuit… This circuit consists of just a few discrete components and one common IC amplifier – the LM380N. It’s simple, cheap, quick to build and works well. I built mine in a steel,...
Category: Schematic
Hi-Z Microphone Preamplifier. Schematic Diagram.
This preamplifier for a high impedance microphone was built into a Harris limiter/compressor which needed a line-level input. Its response is essentially flat from 20Hz-30KHz. The 10uF capacitors are 25v Tantalums, the .01uF capacitors...
Power Supply 12.6V 25A from old Microwave Oven Transformer
Dig out that old microwave oven transformer you’ve been saving and take a look in your junk box. It’s time to build that battery eliminator you need for the mobile rigs. Although the transformer...
Simple 10m CW Transmitter. Circuit Diagram.
The original circuit by the late Doug DeMaw W1FB, differs slightly from the one shown here. Two immediate differences are: A regulated DC supply for better frequency stability and a 2-pole low-pass filter for...
Variable Power Supply Unit. DIY.
This little circuit is a copy of a design which was built around twenty years ago. The heart of the unit is based around a 723 regulator chip. It has variable voltage and current...
6m to 10m converter
This circuit is based around mixer/oscillator IC2. A 50mHz signal is fed to pin1 input of IC2 and mixed with the local oscillator injected at pin7. The resultant output is the antenna frequency minus...
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