Cheap Chinese modules that are available - Page 1
Forum section: electronics / general

author: bills
author_rank: Frequent Contributor
timestamp: November 04, 2015, 05:26:13 am
content: I have been amazed at all the things that are available Power supplies to audio amps and test equipment most are less than the cost of shipping. What have you bought and what is your opinion of these toys? (please include links)bill

author: bills
author_rank: Frequent Contributor
timestamp: November 04, 2015, 05:33:24 am
content: Ok I will start I bought and assembled this kit and it works well not perfect but ok.http://www.banggood.com/86-Plastic-Shell-DIY-Meter-Tester-Kit-For-Capacitance-ESR-Inductance-p-956240.html

author: eas
author_rank: Frequent Contributor
timestamp: November 04, 2015, 06:23:36 am
content: I built thegraphical version of that AVR Transistor tester kit, as have a few others in the forum thread. I did a case mod, and I'm quite happy with it.I also build a minimalistclock kit with a nice big ~1" high 7-segment LED display.There are also those 5-digit 7-segment voltmeters and ammeters people weretalking about earlier this year.

author: tooki
author_rank: Super Contributor
timestamp: November 04, 2015, 05:31:10 pm
content: Quote from: eas on November 04, 2015, 06:23:36 amHow's the timekeeping on your clock been? I have the version without temperature sensing, and it runs substantially fast, gaining something like a minute or two a week.

author: Augustus
author_rank: Regular Contributor
timestamp: November 07, 2015, 02:00:17 pm
content: Haha, that's funny, I build the samebombclock a week ago, they seem to be quite popular here on the EEVBlog forums...Mine gains between 1...2 seconds a day, so the timekeeping is not that great... Don't know why, maybe they use shitty (supercheap) crystals... The external load capacitors supplied with my kit were rated 22pF each, increasing their value may be worth a try, according to a DS1302 application note:

author: tooki
author_rank: Super Contributor
timestamp: November 07, 2015, 08:05:52 pm
content: Quote from: Augustus on November 07, 2015, 02:00:17 pmYes, but the DS1302 datasheets (as well as "Application Note 58: Crystal Considerations for Dallas Real-Time Clocks" you're quoting) both say that the DS1302 has internal capacitors and actually shouldn't have any external ones at all. And indeed, when I built mine, with the two capacitors it came with, it wouldn't oscillate at all. I found references online to DS1302 circuits erroneously including load caps, so I snipped them off. Then it worked fine, except for that it's a smidge fast.I wonder if the crystal they used is the wrong kind -- the datasheet says it must be 6pF, but maybe they chose whatever Shenzhen special they found. (A different Chinese clock kit I built was running at nearly 3x realtime. Turns out the 12MHz crystal was mislabeled and was in fact a 32MHz! Swapping in a real 12MHz fixed that.)

author: Augustus
author_rank: Regular Contributor
timestamp: November 08, 2015, 11:42:35 am
content: Quote from: tooki on November 07, 2015, 08:05:52 pmYes, you're probably right, but on the other hand they knew it wouldn't be the correct one they are going to use, because they designed the circuit with external load caps... My DS1302 runs fine with them, just a tad fast... Or maybe the crystal is fine but they use faked 1302s, who knows...On my next order from Reichelt I will toss this watch crystal into my cart, it's a SMD part but it shouldn't be to much of a problem to bodge it onto the pcb. The manufacturer is part of the Swatch Group, Switzerland, so it should definitely be an improvementhttp://www.reichelt.de/32-768-MS1V-6/3/index.html?&ACTION=3&LA=446&ARTICLE=85043&artnr=32%2C768+MS1V-6&SEARCH=32%2C768+MS1V-6