I also have a bad experience with Aliexpress.
Ordered 5 motors 12 watt BLDC geared motors at topbrand via Aliexpress (95$ a piece exclusive postage). They were advertised as standard out of stock motors.
Quality of the product
Got only 4 (they keep the money for my next buy ) because they only made 5 and killed one.
You have 2 wires for power 24 V, 1 wire for speed (PWM 5V) and 1 wire to connect to ground to change the direction (but not 5V resistant)
on one of the motors the PWM and direction are switched => 5V on direction => another motor dead.
So 5 motors mode only 3 survived the first run.
About quality of service:
I send the money on the 16 th of januari (no paypal or visa)
They confirmed receive of the money on 9 feb (due to chineese new year )
They send the motors on the 4th of april (that is about 2 months to ship the products)
The motors arrived the 14th of april.
So 3 months to send 3 working motors of an order of 5 where I need 4 of them. 600$ down the drain
About service after delivery:
Normally they are very responsive but since I reported the dead motor (with picture of the internals to prove the bad connection): Not a single word.
I have plenty of good experiences with chineese companies but this is way over the top.
My most recent purchase (literally just hours ago) was a bunch of components for a new PC workstation (case, psu, mobo, cpu, ram, hdd, ssd - I already have the video card); my current machine is showing its age (a core2duo w/ 4 gig; running Ubuntu 10.04 LTS) - it was an upgrade in 2009, so I think I got my money out of it. The new machine should be much nicer (and I am moving to crunchbang - lean and mean).
Prior to that was my last "real" purchase:
A guy posted on the r/robotics forum (reddit) that he got a deal on a bunch of old robot arms; among them was an old Rhino Robotics XR arm that needs some TLC:
I got the arm and controller on Friday; waiting to receive the teach pendent (he forgot to send it along, should be here by Wednesday).
It's missing the lower base timing cog wheel and belt; I've got an email in to Rhino to see if they can give me anything to go on in order to replace it. If not, I'll have to fabricate something I guess.
The arm is quite heavy and robust (so is the controller/power-supply). It needs some cleaning and such as well, but overall is in great shape. One of the quadrature encoder brackets was bent during shipping (easy enough to repair). The controller may or may not work properly - the guy who sold it to me said that the pendent didn't seem to power up when he connected it, but that the controller seemed to be controlling the motors in some fashion when he applied power.
Some of what he said didn't make sense, though, as the motors are brushed DC gear motors (Pittman - very high quality there) with quad encoders - and he said he couldn't turn them when the power was on (not sure how they could "hold station" with only quad-encoders).
Anyhow, worst case is that I'll have to build my own controller in some fashion (I might do that anyhow, but I want to try to get the original controller running first). My plan is restoration of the robot as part of my "vintage computer and robotics" collection.
If anyone has any good information on the robot (looking for actual manuals if possible), I'm all eyes. I've found the common internet stuff - not much out there, unfortunately...
Jantje:
I also have a bad experience with Aliexpress.
Ordered 5 motors 12 watt BLDC geared motors at topbrand via Aliexpress (95$ a piece exclusive postage). They were advertised as standard out of stock motors.
Quality of the product
Got only 4 (they keep the money for my next buy ) because they only made 5 and killed one.
You have 2 wires for power 24 V, 1 wire for speed (PWM 5V) and 1 wire to connect to ground to change the direction (but not 5V resistant)
on one of the motors the PWM and direction are switched => 5V on direction => another motor dead.
So 5 motors mode only 3 survived the first run.
About quality of service:
I send the money on the 16 th of januari (no paypal or visa)
They confirmed receive of the money on 9 feb (due to chineese new year )
They send the motors on the 4th of april (that is about 2 months to ship the products)
The motors arrived the 14th of april.
So 3 months to send 3 working motors of an order of 5 where I need 4 of them. 600$ down the drain
About service after delivery:
Normally they are very responsive but since I reported the dead motor (with picture of the internals to prove the bad connection): Not a single word.
I have plenty of good experiences with chineese companies but this is way over the top.
Jantje
It even got worse.
I attached the 2 motors to my robot and .... nothing happened.
I tested the torque and the torque is 0.5NM where the spec of the motor states 2NM.
I had to make a movie to show that the motor simply can not lift more than 0.7KG with a wheel of 0.2m wheel.
The response op topband is even more baffling than anything else I heard from them. I quote:
controller engineer told me that this motor is without hall sensor, which means if the motor works with higher loading, it will work bad.
usually, the non- hall sensor brushless motor is loaded with a fan or blower which is not big.
you can't always complain our motor, I think you also should consider other possibilities.
So I give them my specs for a driver motor.
Technical specs:
Voltage up to 29V (battery fluctuates between 29V and 22V)
Driver can be any voltage. Already available are regulated 5V 12V
Stall torque at the wheels should be minimum 8.9NM
rated torque at the wheels should be minimum 1.5NM
rpm at the wheels should be minimum 61
The output watt at the wheels should be substantial above 15
They propose this motor and now it is all my fault ......
So this 95 USdollar motor has a torque of 0.5NM at a RPM of 61. I seriously got ripped off.
Jantje:
So this 95 USdollar motor is not as advertised.
FIFY. Contact your credit card company and dispute the transaction as not as advertised.
I have been really stupid on this site.no paypal no visa. Direct bank transfer.
Another 30 euro costs.
....
I know .... hard lesson, won't do it again.
The Arduino Zero announcement got me all excited, but the SAM D21s aren't available yet, so I thought this would be a start (Atmel SAM D20 Xplained Pro).
Also some interesting Hall-effect sensors from Honeywell. Digital push-pull output, omnipolar operation (senses N or S pole), interesting high-sensitivity, low power design.
Jantje:
I have been really stupid on this site.no paypal no visa. Direct bank transfer.
Another 30 euro costs.
....
I know .... hard lesson, won't do it again.
Jantje
I'm a bit confused by this. Aliexpress certainly offer payment via Visa or Mastercard, among other options. (No Paypal though.) I've always used a Mastercard for payment.
Sounds like you weren't actually buying through Aliexpress, but rather directly from the company (Topband)?
Either that, or perhaps you were going through Alibaba rather than Aliexpress (which is more wholesale/b2b oriented, rather than Aliexpress, which is more ebay-like and retail oriented. Prices and "minimum buy" quantities generally reflect that, too.)
(Sorry, I had a quick look through the datasheet and didn't actually spot anything particularly stand-out that caught my attention, but perhaps I missed something.)
For M0-class devices I'm quite impressed with the NXP "switch matrix" for IO pin function configuration.Just such a cool and clever (and even useful!) feature. I've been playing with some LPC810 8-pin DIPs, looking at them as alternative to ATtiny85s for some applications.
Unfortunately, NXP only offer one other LPC in a DIP package, the LPC1114, which is nice, but only offers 32KB flash and 4KB ram, so apart from being faster (50MHz), doesn't offer much more than a 328-class device, really. Otherwise I'd be all over it.
The free LPCXpresso programming environment is decent enough, too, although a bit too "Eclipsy" for my taste (which is not surprising since the code base is derived from Eclipse, apparently.)
Moving up the ARM foodchain a bit I'm really impressed with what Paul Stoffregen has done with his latest Teensy 3.1 offering. Even 5V tolerant digital IO pins! Just too much bang for buck. It almost hurts to read the datasheet.
Got my Official PJRC Teensy 3.1 through OSH Park, they're still on sale for $17 ea. Shipping ran me less than $3.
One minor PITA was having to get cables to fit, I got a multi-pack of cellphone cables, the USB plug is tiny.
pico:
I'm a bit confused by this. Aliexpress certainly offer payment via Visa or Mastercard, among other options. (No Paypal though.) I've always used a Mastercard for payment.
Sounds like you weren't actually buying through Aliexpress, but rather directly from the company (Topband)?
Either that, or perhaps you were going through Alibaba rather than Aliexpress (which is more wholesale/b2b oriented, rather than Aliexpress, which is more ebay-like and retail oriented. Prices and "minimum buy" quantities generally reflect that, too.)
Sorry my bad.
I went through Alibaba and then via mail directly. Therefore Alibaba doesn't even know about this deal. As a result I can't even complain or give negative feedback on Alibaba.
I know
[quote author=Jack Christensen link=topic=91399.msg1754425#msg1754425 date=1402024959]
Thought the SAM D20/D21 MCUs were pretty interesting.
What aspect(s) in particular?
[/quote]
The SAM Ds also have a switch matrix feature which I thought was cool. As are the multiple SERCOM modules, each of which can be configured as SPI, I2C, serial, etc. Bang-for-the-buck is fairly amazing, the top end SAM D20 is under $5 in single quantities, has 256kB flash and 32kB SRAM, and the smaller versions go for half that. I thought the AVRs were pretty reasonably priced, but a 32-bit 48MHz ARM with more and better peripherals makes them seem relatively expensive!
I've looked at the LPC812 as well, and it is also pretty impressive. I was hoping that with the Atmel MCUs, there might be less of a learning curve given that I was pretty comfortable with the AVRs. Not too sure about that now, I should know better than to believe the marketing hype. I'm just starting to explore the ASF doc, lots to digest there, basically a whole layer of APIs to interface to the hardware. It's either that or digest the entire datasheet, which is formidable, then program down to the bare metal. Of course I didn't learn AVRs in a day either. But the SAM chip is more complex in every way. I was looking at the ports last night, instead of three registers that the AVRs use to control the ports, there are no less than thirteen per port.
So we shall see. I'd be interested to hear what you've done with the LPCs and especially interested in how you got up to speed with them. I see that NXP has LPCOpen which I think might correspond to ASF, at least roughly. I think I've got everything I need for the SAM D20 now, took just a bit to find all the parts and there's a lot of learning ahead still of course. Google has not been my friend, there just does not seem to be a lot of learning resources out there for the SAM Ds.
The SAM Ds also have a switch matrix feature which I thought was cool.
[/quote]
There you go, I missed that (and I was actually looking for it.)
I'm actually a bit surprised at what Atmel are doing in their ARM line, and perhaps this prejudices me somewhat. To me, they seem to be a bit left-footed somehow in producing a line of chips which synergize well with their AVR line. For example, everyone seems to offer 5V tolerant IO pins on the ARM uCs-- except Atmel! That strikes me as downright odd.
It's been my feeling since the Due that the only reason to choose the ATmel ARM chips for the next generation Arduinos is because of the business relationship Arduino has with Atmel, rather than the technical merits of their ARM chips.I like AVR and I like ARM -- I'm just not been in love with Atmel ARM (so far, anyway.)
I think that's true across the industry for the ARM uCs, just amazing bang for buck, which is why I think they are becoming so dominant.
Yeah, I think ARM is ARM to a certain extent; you learn the architecture, not the manufacturer so much. I think what varies from manufacturer to manufacturer is the quality of the tools, though. Speaking of which, Atmel have recently released a new very affordable range of debuggers (the "-ICE" range) that cover both AVR and ARM targets. If I was going to get into Atmel ARM, I'd definitely spring for one.
Yup, which is why I suspect that the old 8-bitters will never die away completely. Sometimes that relative simplicity is a definite plus. Paradoxically though, they may get more and more expensive, relatively speaking!
I'm still at the beginner stage myself with the LPCs, but I've been quite pleased with what I've seen so far. My feeling is that everything has been made as simple as possible by NXP with the tools and online documentation they offer, and so it comes down to just putting the time in. Graynomad (Rob) has put much more time into the LPC stuff I think, and he seems to making good progress with it.
I think you are right that LPCOpen is roughly equivalent to ASF, but I haven't really got into that as yet. I should really decide to do a proper project with one of these things. Learning seems to accelerate quickly when things start to get "real".
Definitely check out those new -ICE debuggers if you haven't already. The only thing I prefer about my AVR Dragon is that it can also do HVP, which the new debuggers can't (they can only do serial and JTAG programming, I think.)
Your choice of such a term to signify a negative action might be offensive of those of us that are left-foot and hand dominate, but I'll forgive you just this one time.
Your choice of such a term to signify a negative action might be offensive of those of us that are left-foot and hand dominate, but I'll forgive you just this one time.
Not for nothing is the Latin for "left", "sinister".....
Your choice of such a term to signify a negative action might be offensive of those of us that are left-foot and hand dominate, but I'll forgive you just this one time.
Not for nothing is the Latin for "left", "sinister".....
Not for nothing is Latin said to be a dead language.
retrolefty:
those of us that are left-foot and hand dominate
I hope you meant "dominant", but in case you really did mean "dominate", it just reinforces my strong suspicions that the lefties among us really need to be kept under the strictest surveillance and control.
Otherwise, things might get "out of hand" quickly, so to speak.
) because they only made 5 and killed one.
