Cheap MAX7219s from China - Page 1
Forum section: electronics / general

author: robertbaruch
author_rank: Regular Contributor
timestamp: December 17, 2016, 12:06:37 am
content: I know intellectually that you can get cheap stuff from China. Buthere's an exampleof a board with a MAX7219 and two 4-digit 7-segment displays, for US$2.29 delivered. Note that in the US, you can get aMAX7219for US$5.48 each in quantity 1000.I understand this intellectually. I'm having a hard time getting a grip on it, though. Aside from the slow boat, if you want a MAX7219, you may as well get one from ebay and get two free LED displays along with it.

author: robertbaruch
author_rank: Regular Contributor
timestamp: December 17, 2016, 12:11:01 am
content: Ah, it turns out this wascovered years agofairly thoroughly.Archived linkto one of the articles in that thread. Basically, feel bad if you go for the cheap stuff, and don't be surprised when they don't work.

author: wraper
author_rank: Unknown
timestamp: December 17, 2016, 12:19:13 am
content: http://forum.arduino.cc/index.php?topic=233109.0They are fakes with much smaller die.

author: ebclr
author_rank: Super Contributor
timestamp: January 01, 2017, 08:26:29 pm
content: In Fact that is a extremelly expensive solution, Tm 1638 do the same and keyboard handle for 1/10 of price 0.14 USDhttps://world.taobao.com/item/20108207939.htm?spm=a312a.7700714.0.0.LSOYa9#detailhttp://www.ebay.com/itm/1PCS-8-Bit-Digital-LED-Tube-8-Bit-TM1638-8-Key-Display-Module-For-AVR-Arduino-/222207109725?hash=item33bc936a5d:g:PoEAAOSwdzVXnx2w

author: Yansi
author_rank: Super Contributor
timestamp: January 01, 2017, 08:41:45 pm
content: The MAX7219 are very old expensive chips. I got a shitload of them with a truckload of some old garbage PCBs, where two of these on each board were driving loads of 7seg displays.I have done a few projects with these 7219s, but I don't like these chips. Very low driving current and due to the 1/8 multiplexing ratio combined with the usual low brightness LED displays equals almost useless product.

author: VK3DRB
author_rank: Super Contributor
timestamp: January 02, 2017, 01:19:02 am
content: Quote from: ebclr on January 01, 2017, 08:26:29 pmThe eBay PCBs are rated at 9500 RPM.Minimum wind pressure : 0.. 120 Pa.Noise index : 41.9 dB (A)The seller clearly has no idea what he is selling. Still it is cheap and the PCB layout looks OK, except '+' marking for the anode of a diode is unorthodox. If the parts were bought from Digikey, you'd be up for roughly $30 not including the raw card, plus $30 shipping to Australia. RS/Element 14, probably $40 all up (Just guesstimating).The Australian version ($2.79 including FREE shipping). That's less than a cup of coffee.http://www.ebay.com.au/itm/1PCS-8-Bit-Digital-LED-Tube-8-Bit-TM1638-8-Key-Display-Module-For-AVR-Arduino/222207109725?_trksid=p2045573.c100033.m2042&_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D39923%26meid%3D0fa8bb0b938643efae05515f388f8ac8%26pid%3D100033%26rk%3D1%26rkt%3D1%26sd%3D222207109725We clearly cannot compete with cheap Chinese labour, even if they have no idea what they are selling. Trumps 45% tax election lie still won't dent the cheap imports from China into the US.

author: rrinker
author_rank: Super Contributor
timestamp: January 02, 2017, 01:31:41 am
content: That's the problem with those cheap versions - you can't spin the too fast or all the electrons fly out. Ditto too much wind speed, it just blows the electrons away.

author: klunkerbus
author_rank: Unknown
timestamp: January 02, 2017, 01:51:06 am
content: For the record, AMS offers the AS1106 and AS1107 that are pin compatible with the Maxim MAX7219 and MAX7221 parts. You'll find they are cheaper than the Maxim parts. Not as cheap as the counterfeit Maxim parts, but still a few USD less per part than real Maxim parts.I built a project earlier this year with 24 of the AS1107 parts driving 8x8 LED matrices. I've also experimented with a few of the unrealistically cheap MAX7219 boards and haven't noticed any issues with them, although I admit I've had no reason to test them at the max LED current specified by Maxim.