Chinese decade resistance box teardown photos - Page 1
Forum section: electronics / general

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: April 30, 2013, 06:08:59 pm
content: Having watched Dave's recent teardown video of his auction scored metrology grade decade resistance box, I thought it might be a good idea to get one of these boxes. I don't have thousands of dollars to spend on one so I look north of border to ChinaThis thing claims 0.1% accuracy on most of the ranges and does seem to be within spec according to my second hand HP3457A (which I have no idea when it was last calibrated). It actually isn't exactly very cheap by Chinese standard, costing me over $150, but for a 8-decade box I thought it wasn't too bad. If nothing else it'd at least be slightly interesting to see what it is like inside

author: Lightages
author_rank: Unknown
timestamp: April 30, 2013, 06:53:50 pm
content: That actually looks pretty good. If it is less than $200 and is as accurate as it claims it is serious competition to the other more famous brands. Of course how it stands up over time is yet to be seen. Are you thinking of selling these?

author: ddavidebor
author_rank: Super Contributor
timestamp: April 30, 2013, 07:50:14 pm
content: how much cost this decade box?i've seen some of this unit on goodluckbuy.com, but they was without price.

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: May 01, 2013, 12:41:25 am
content: The manufacturer of this box actually specializes in making this sort of stuff. There's a more complete list of their decade resistance boxes here (in Chinese):http://www.zychina.com/product/Product_list.asp?CateID=12&CateName=%D6%B1%C1%F7%B5%E7%D7%E8%CF%E4I picked this particular one (ZA99-IIA) because it has the widest range (8 decades). They do have some higher end (but fewer decades) ones that offer up to 0.01% accuracy, but those cost a fair bit more. I reckon for hobbyist use a wider range is more useful and 0.1% is more than I will ever need.The main downside of their boxes is the power rating. They are mostly rated at nominal 0.1W and 0.2W max, so you can't really send a lot of current through it.I didn't really plan on selling them but if anyone's interest I can help source one and maybe charge a 10-15% fee for the service, plus shipping. For this particular model I pictured shipping should be no more than $30 for most countries, so including my fee it should come just under $200.

author: bilko
author_rank: Frequent Contributor
timestamp: May 01, 2013, 07:42:02 pm
content: What's it like as a decade Inductance box ?Lots of coils everywhere in there

author: JackOfVA
author_rank: Unknown
timestamp: May 01, 2013, 08:06:21 pm
content: I might well be interested in one at those prices and terms.Construction quality looks more than decent, particularly considering the price.I assume the resistors are wound in an inductance cancelling configuration, but it would be helpful to verify that.

author: bilko
author_rank: Frequent Contributor
timestamp: May 01, 2013, 10:10:51 pm
content: Quote from: JackOfVA on May 01, 2013, 08:06:21 pmIt is possible to 'minimise' inductance with the winding, note the coils for the low resistance range, 2nd photo are wound part contrary half way to minimise inductance, however long leads everywhere, OK for DC and LF AC

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: May 02, 2013, 01:01:19 am
content: Quote from: JackOfVA on May 01, 2013, 08:06:21 pmThe front panel of the box actually says “DC resistance box” in Chinese, so I suppose it's not designed for AC applications. Perhaps I can try to measure the inductance with my LCR meter later when I am back in the lab.

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: May 02, 2013, 04:08:02 pm
content: I've just noticed that the same manufacturer actually makes a few AC/DC resistance boxes too:http://www.zychina.com/product/Product_list.asp?CateID=1&CateName=%BD%BB%D6%B1%C1%F7%B5%E7%D7%E8%CF%E4