Electronics > Projects, Designs, and Technical Stuff
Yet another resistance decade box
PeterZ:
Meanwhile, i've built one decade R box using the PCBs i have and set of 1% resistors (1M, 100k, 10k, 1k, 100R, 10R):
The total resistance when all switches are set to 0 is about 370mOhm.
--- Quote from: Dave on May 16, 2016, 05:06:06 pm ---You could remove those direction selection jumpers on the bottom and reduce the size of the board slightly. It doesn't matter which way the current flows through a resistor.
--- End quote ---
I used these jumpers only to make the wiring easier, like this:
Removed them in the final version. The PCB size is 46.5x46mm (filled up the remaining space with an SOP/SOIC adapter, adapters are always handy).
Dave:
You can still wire them the exact same way even without those jumpers. Again, they are resistors, it makes no difference which direction the current flows through them.
Fortran:
Nice! :-+
If you're making both BBM and MBB it might be a good idea to put that somewhere on the silkscreen so you don't have to take it apart to know which type it is.
For a group buy, it would be more economical to arrange them 1x6 or 2x6.
The 50x50 format is great for those who want to order themselves though.
linux-works:
even more, to differentiate, put ribbed edge or something on one but different style on the other. something physical that you can use as a cue. I always like seeing stuff like that.
(OT: pet peeve of mine: when you have a thruhole electrolytic and your silk symbol has the index (plus or dot or whatever) INSIDE the inscribe circle, so that once the cap is installed, you can't visually tell, easily, if its in right or reversed. just another plus symbol added outside the cap circle would do wonders to allow desk checking.)
PeterZ:
Okay, the github repo is updated with multiple versions of the board:
LINK
including:
* single boards - if you'd panelize them yourself
* about 50x50mm format - 4xMBB, 4xBMM and mixed 2xMBB+2xBMM versions and an SOP/SOIC to breadboard adapter to fill up the space
* 1x6 MBB
* 2x6 MBBI made only the MBB version of the last 1x6 and 2x6 formats. I think this one will be better suited for R decade boxes.
The MBB version is not 100% verified yet. I am going to order a small set of ENIG ones and build another, more precise box with 0.1% tolerance resistors.
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