Milliohm meter

This is a simple but accurate milliohm meter with a range of 0 – 2000 milliohm (= 2 Ohm). It has a typical accuracy of 2%-3%. Unlike other designs this circuits doesn’t use large currents to measure these small resistances. So there is no risk to damage components. A small alternating current is used […]

JFET testing

For an upcoming RF amplifier project I needed a couple of JFETs. The spread in device characteristics is quit broad. For the BF256B Vp ranges from -0.5 to -8.0V ( a factor 16! ) and IDSS ranges from 6 mA to 13 mA. Since, I bought a small stock of them, I decided to […]

Sweep control oscillator

The purpose of this device is to help you sweep an audio or rf filter. It outputs a 0..10V sawtooth that can be used to control a sinus/ function generator or an rf generator. Together with a CRO oscilloscope, a millivolt meter and or power meter this can be used to accurately characterize a […]

PM5324 oscillator

A recent question in a CircuitsOnline thread (link here), raised my interest in the oscillator section of this RF sweep generator. The oscillator section is around the (ECO) emitter coupled oscillator topology. This topology will oscillate at almost any frequency with almost any LC combination and is not critical with transistor types (of course […]

LCR bridge



The usage of inductors in RF circuits is often intrinsic to its operation. Unfortunately, the measurement of small values of inductance is often difficult without specialized equipment. If, you have the ability to measure frequency, either directly with a frequency counter or indirect with an oscilloscope, this burden can easily be overcome.


GDO circuits bonanza !

The Gate Dip Oscillator (GDO) is one of the most useful tools for the radio amateur. You can use it to tune LC circuits, as test RF source, check antennas, etc. This GDO circuits bonanza features many previously unpublished GDO circuits from (primarily) Dutch magazines and books.

Bouwen en luisteren – IAN R. SINCLAIR

This […]

Super Fine Tip test probes

These test probes wereld made several years ago and have proven to be very useful in many applications. The small tip allows you to probe even the tiniest SMT components. Because the tip is really, really sharp (don’t ask me how I know… ouch) it allows you to breach residue of solder flux or […]