Tools and measuring circuit diagrams

Two Simple Crystal Test Circuits

Two simple test circuits to check operation of quartz crystals.

Quick on-board Junction Tester

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

Electromagnetic Field Detector

This circuit is sensitive to low frequency electromagnetic radiation and will detect for example hidden wiring or the field that encompasses a transformer.

Milligaus Meter

The circuit provides an easy yet reliable way to detect the intensity of a.c. (or e.l.f.) fields around the home or workplace.