Another decade resistor box - Page 1
Forum section: electronics / projects

author: nuno
author_rank: Frequent Contributor
timestamp: October 04, 2014, 12:18:46 pm
content: Just another resistor box, with big clunky buttons. I did this "recently" just because it's one of those must-do traditional projects for whom likes electronics and as a kid I didn't do one.Since the rotary switches have more than the needed 10 positions, I added a "1Meg" position to all decades so it can do some >1M resistor values. Also added an "open" position (oo resistance).Used 1% 0.6W resistors except for the 0.1K, 1K and 10K where I used 0.1% as I find more precision on those decades to be more useful for the things I do.I used "make-before-break" rotary switches, so there's no infinte resistance moment when changing the value. This is not mentioned on all box projects I've seen.One "funny" thing I didn't know about these rotary switches (never had used one before) is that one only had 9 positions. So I almost sent it back as defective until I found another with only 8 positions and started exploring them, finding out they have a kind of a washer you can use to choose how many useful positions the switch should have. Never seen that mentioned nowhere, not even in the switch's datasheet.Cheers!

author: ivan747
author_rank: Super Contributor
timestamp: October 04, 2014, 01:43:36 pm
content: The open position seems very helpful for some analog circuits. It'snice that you did something with the extra positions. Cheers!

author: ivan747
author_rank: Super Contributor
timestamp: October 05, 2014, 01:31:22 am
content: How and where did you print the labeling on the case?

author: zapta
author_rank: Super Contributor
timestamp: October 07, 2014, 03:09:51 pm
content: Quote from: nuno on October 04, 2014, 12:18:46 pmIt's never too late to have a happy childhood ;-)It looks professional.

author: nuno
author_rank: Frequent Contributor
timestamp: October 07, 2014, 10:22:48 pm
content: Thanks guysI made the labelling in InkScape, then printed on a normal laser printer (B&W) and glued it on the box's top, then put a layer of transparent plastic sheet with glue (kind of a glueing tape, but in "sheet" and bit thicker, I don't know the name in English, maybe "transparent sticker sheet"). InkScape file in attach.

author: SArepairman
author_rank: Frequent Contributor
timestamp: October 08, 2014, 01:56:20 am
content: the one happy thread on 10 page (as far as I am willing to check)no one else is happy, the ppms are not good enough.you are the one person on the forum without crippling OCD. congratulations. everyone else here would be panicing about how their box would stand up against a 8.5 digit meter.thats right, one day you are gonna save the world with a decade resistance box, you will need to calibrate the guidance system of a nuclear missile in deep space in order to blow up an asteroid. tempco will be the deciding factor for the fate of the earthwell, at least we are not on some gun forum, praying that one day the 50000 rounds of ammunition we spent our retirement money on is going to come in handy.

author: nuno
author_rank: Frequent Contributor
timestamp: October 08, 2014, 09:12:18 am
content: I have no 8.5 digit meter so I'm happyIgnorance can be blessing sometimes

author: lapoltba
author_rank: Contributor
timestamp: October 08, 2014, 11:10:08 am
content: Very nice work! The front panel with those knobs is very clean.I should make myself one of these for the same reasons you did. How about a few pictures of the guts, or are you hiding something behind that pretty panel?

author: robrenz
author_rank: Super Contributor
timestamp: October 08, 2014, 11:58:24 am
content: Very nice professional looking job!

author: nuno
author_rank: Frequent Contributor
timestamp: October 08, 2014, 09:29:08 pm
content: Thanks again guys. I have a photo taken while building it, it's pretty straightforward, I think it's not worth opening the thing to take another, so I'll leave the "mid-build" one.