Sunday, June 25, 2023

Simple ESR meter

 Almost a copy from here.


Only added provision for self "TEST", that is; the switch disconnects the terminals and connect internally to know resistor values via rotary switch (minimum 2 Ohm since had nothing smaller at the time). Also add zeroing via a pot on R24 place.

Diagram from the original site:




and during testing:

Works nice, handy for testing old caps.

Have a nice day!

Saturday, April 29, 2023

Simple Capacitance Meter

 As title says; a simple capacitance meter.

One youtube video by VK3YE was enough to get me started building, after all, the meter that I was using before was not behaving correctly (latter found the problem).

The outcome was this:

(scale on the left switch is wrongly printed, where is x2 should be x0.5/divide by 2)

During build:

Making the scale:
The scale on the meter was changed from the original 0-50 to 0-100, the easiest way was to scan the original face-place and then edit on a image editor.

To calibrate I used a 68pF and 27pF capacitor, the idea was not to have highest precision possible only to be in a position of having certain about unmarked capacitors.

Some description/schematic from here and here:

I used different Ge diodes and the 10K pot was changed for 2 of 5K in series to give better adjustment range. The Zener was changed to 6.8v.
Ranges like this:

E: 100pF
D: 1nF
C: 10nF
B: 100nF
A: 1uF


Have a nice day!

Saturday, April 01, 2023

Clock for a clock - 32.768Khz oscillator

 Not planing to build any electronic clock but who knows. Just found one of those round clock crystals and decided to give it a go.

The diagram and assembly

  The output, ideally it will be 32.768Khz so that diving for the same number will tick at 1s:

As low as it was possible to adjust, it will be less than 1s faster per day... time flies!

Have a nice day!

Sunday, March 05, 2023

Interdigital Bandpass Filter for 1.2Ghz / 23cm

 Part of a project on 1.2Ghz that will include this band-pass filter.

Main dimensions got online via the tool here:

Some details of similar construction for different frequency range (ADS-B) here:


My construction:


Used FR4 double sided PCB for the sides and brass for elements, bottom and top


Online results example for dimensions:

 And the outcome:


Regarding results; not the best optimization for attenuation but not bad either considering the dimensions and construction not to the greatest dimensional andards:

Have a nice day!