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Author Topic: Your latest purchase  (Read 112020 times)
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nr Bundaberg, Australia
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That's one of the key (and under-appreciated) features of that chip, it's an XMOS one way around but can easily be made into a SOWX simply by turning it 180 degrees. As to the difference in functionality, that's not documented very well though.

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Rob
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Rob Gray aka the GRAYnomad www.robgray.com

field road, jupiter creek
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You got me wondering if it'll execute code in reverse

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Grand Blanc, MI, USA
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You got me wondering if it'll execute code in reverse

It should be the bomb running a disassembler.
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MCP79411/12 RTC ... "One Million Ohms" ATtiny kit ... available at http://www.tindie.com/stores/JChristensen/

field road, jupiter creek
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yep, calculating reverse offsets for relative branches will be tricky

but at least "stack collision with heap" will be harder to make happen

Although the idea of negative address space is hard to get your head around
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Pittsburgh, PA, USA
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Just swap power and ground?
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I find it harder to express logic in English than in Code.
Sometimes an example says more than many times as many words.

field road, jupiter creek
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So that's where your handle comes from!
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Pittsburgh, PA, USA
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Learning hardware from a couple of EE's, when they got marginal boards there was the practice of burning hairline traces while chanting "Go for smoke! Go for smoke!". It's kind of a geek rite.
Later when I was involved it was a phrase to let me know I was doing something wrong, but phrased as a question. I guess they got tired of "Nooooo!" and "That was stupid".
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I find it harder to express logic in English than in Code.
Sometimes an example says more than many times as many words.

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Bought 20 LM2940 5V TO220 regulators on Aliexpress and got burned... Tried out 2 and they are crap. If I try to draw more then 200mA from them the output voltage drops to 2-3V. The input voltage doesn't seem to matter, tried feeding them 6 to 12V. With currents less then 200mA they seem be fine.
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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  smiley-eek) 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  smiley-eek)
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  smiley-eek

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



 
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Pittsburgh, PA, USA
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Maybe Aliexpress should have a picture of an old style Chinese ship as their logo? You know the type, a Junk.
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I find it harder to express logic in English than in Code.
Sometimes an example says more than many times as many words.

Phoenix, Arizona USA
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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:

http://www.embeddedrelated.com/showarticle/591.php  (pictures of the arm near the bottom of the post)

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...
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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  smiley-eek) 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  smiley-eek)
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  smiley-eek

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:
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.
Quote
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 ...... smiley-eek

So this 95 USdollar motor has a torque of 0.5NM at a RPM of 61. I seriously got ripped off.

My conclusion: stay away from topband.

Frustratedly yours
Jantje
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Danger Boy
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So this 95 USdollar motor is not as advertised.

FIFY.  Contact your credit card company and dispute the transaction as not as advertised.
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I have only come here seeking knowledge. Things they would not teach me of in college.

Belgium
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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.

Jantje
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Grand Blanc, MI, USA
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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.


* SAMD20_Xplained_PRO_overview.jpg (273.96 KB, 709x836 - viewed 24 times.)
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MCP79411/12 RTC ... "One Million Ohms" ATtiny kit ... available at http://www.tindie.com/stores/JChristensen/

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