Electronics > Projects, Designs, and Technical Stuff
Yet another resistance decade box
PeterZ:
I got some of these cheap thumb wheel switches (smaller ones, ~18mm height) recently.
Unfortunately, the overall quality and the drilling precision, as you can see on the attached picture, may occasionally lead to increased contact resistance. Pretty significant increase ;)
Since it is a PCB, i decided i'll make a new one, 0.6mm thick, easy to cut and trim with scissors, already accommodating footprints for one decade of 1206 resistors.
The small jumpers near the terminals pads allow to configure them as input or output. Makes the wiring easier:
--- Code: --- 1R 10R 100R 1k
out---+ +---+ +--- ... +
| | | | |
+---+ +---+ +--- in
--- End code ---
The PCB with 6 such modules is smaller than 5x5cm. I designed it using SprintLayout6.
Design files (gerbers for 1206, 0805 version and the original SprintLayout project) are HERE (github repo).
Dave:
Pretty clever idea. :-+
What sort of resistance are you getting on zero setting?
PeterZ:
Thanks! :) Using 4 wire method on my 3456A the measured resistance on 0 setting is about 60 mOhm.
I didn't bother to order these PCBs with gold plated pads, it's just a standard lead free HASL.
Fortran:
Clever indeed. :-+
Do they still stack together despite the added height of 1206?
I might steal this idea and make a larger batch with ENIG.
matseng:
--- Quote from: Fortran on May 16, 2016, 12:27:12 pm ---I might steal this idea and make a larger batch with ENIG.
--- End quote ---
If you do and decide to sell some of the pcbs please sign me up for a dozen.... :-+
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