Author Topic: What did you buy today? Post your latest purchase!  (Read 1321210 times)

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Online blueskull

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Re: What did you buy today? Post your latest purchase!
« Reply #5075 on: December 15, 2017, 10:11:53 am »
Since those powerful chips are so damn cheap, maybe I can practice BGA routing and soldering with them? Maybe I can get a board made for about $50, and if it works, I can create my own BSP. I know for a fact that NXP mainlined the drivers for this chip, so it is very likely I can get stock Ubuntu or Debian armhf running on it.

1. You can, but not with $50 PCB. You need at least 4-mil process for 4-layer, or preferably 6-layer, unless you want to use plugged micro vias.
2. Routing dual 16-bit DDR is gonna be a great fun. When you bifurcate any high speed signal, things get rather nasty rather quickly.
3. Don't use mainline kernel and u-boot. Use NXP's own one. They have an official BSP if you just want to boot the chip, and a community one if you want to customize it. You will need basics on Yocto.
4. Prepare at least 16GB of RAM. Yocto for iMX6 fails to compile with 8GB if you don't have swap. It's one of the small things that have wasted me 2 days.
5. Yocto is not very popular in China, expect to ask no one and read a lot of materials in English. Prepare to buy books from abroad. Packt has a few books, one of them is specifically written for fsl-community-bsp (the BSP you will be using), the book is called "Embedded Linux Projects Using Yocto Project Cookbooks".
 

Offline technix

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Re: What did you buy today? Post your latest purchase!
« Reply #5076 on: December 15, 2017, 11:59:18 am »
Since those powerful chips are so damn cheap, maybe I can practice BGA routing and soldering with them? Maybe I can get a board made for about $50, and if it works, I can create my own BSP. I know for a fact that NXP mainlined the drivers for this chip, so it is very likely I can get stock Ubuntu or Debian armhf running on it.

1. You can, but not with $50 PCB. You need at least 4-mil process for 4-layer, or preferably 6-layer, unless you want to use plugged micro vias.
It would be much cheaper than buying the 4 chips alone anyway. So still worth it.
2. Routing dual 16-bit DDR is gonna be a great fun. When you bifurcate any high speed signal, things get rather nasty rather quickly.
Or can I just stick a laptop memory module onto it? That would be plain point to point connection from the chip to the RAM slot connector.
3. Don't use mainline kernel and u-boot. Use NXP's own one. They have an official BSP if you just want to boot the chip, and a community one if you want to customize it. You will need basics on Yocto.
I don't plan to use Yocto at all. Maybe I will need the kernel if it is the latest version, but I definitely plan to spend zero time on compiling the userland at all and just grab Debian or Ubuntu armhf. In fact the whole point of preferring mainline kernel over NXP's is because of Debian.
4. Prepare at least 16GB of RAM. Yocto for iMX6 fails to compile with 8GB if you don't have swap. It's one of the small things that have wasted me 2 days.
I have an idling server with 128GB RAM and 32 processor threads. Compiling the kernel should be a breeze.
5. Yocto is not very popular in China, expect to ask no one and read a lot of materials in English. Prepare to buy books from abroad. Packt has a few books, one of them is specifically written for fsl-community-bsp (the BSP you will be using), the book is called "Embedded Linux Projects Using Yocto Project Cookbooks".
First off, I am not planning on using Yocto in the first place. Second, I would rather not read Chinese documentations anyway since a lot of the writers of those provide no insight on what is going on anyway.

In fact, for the software, instead of u-boot directly launching Linux kernel, I might place a TiernoCore based UEFI in there so it can launch Linux, Darwin (the underlying UNIX part of macOS and iOS) and Windows.
« Last Edit: December 15, 2017, 12:41:36 pm by technix »
 

Offline Specmaster

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Re: What did you buy today? Post your latest purchase!
« Reply #5077 on: December 15, 2017, 03:35:19 pm »
I liked the first one so much I went and got :-+ yet another

Who let Murphy in?
 

Online Mr. Scram

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Re: What did you buy today? Post your latest purchase!
« Reply #5078 on: December 15, 2017, 03:37:18 pm »
I liked the first one so much I went and got :-+ yet another


How much did you pay this time?
 

Offline Specmaster

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Re: What did you buy today? Post your latest purchase!
« Reply #5079 on: December 15, 2017, 03:39:53 pm »
How much did you pay?
Who let Murphy in?
 

Offline ChrisLX200

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Re: What did you buy today? Post your latest purchase!
« Reply #5080 on: December 15, 2017, 05:03:01 pm »
I liked the first one so much I went and got :-+ yet another


Nice catch :)  What oscillators do these have in them?
 

Offline mtdoc

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Re: What did you buy today? Post your latest purchase!
« Reply #5081 on: December 16, 2017, 10:41:14 pm »
Took advantage of the 25% off coupon and picked up a Harbor Freight Mini Mill.  Lots of info about these online and they get decent reviews. Hard to go wrong for under $600 delivered.  Now accumulating the necessary tooling from HF and LittleMachineShop.com.  I'm a machinist newbie but have ordered some books and am looking forward to playing around with this.

 
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Offline bitseeker

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Re: What did you buy today? Post your latest purchase!
« Reply #5082 on: December 17, 2017, 12:57:59 am »
Ooh, that looks like fun, mtdoc!
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Offline mtdoc

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Re: What did you buy today? Post your latest purchase!
« Reply #5083 on: December 17, 2017, 01:56:57 am »
Ooh, that looks like fun, mtdoc!

Ha! we'll see.  I'm quickly realizing that there's a whole new rabbit whole to fall into with these mini mills......
 
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Offline tablatronix

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Re: What did you buy today? Post your latest purchase!
« Reply #5084 on: December 17, 2017, 02:25:59 am »
Took advantage of the 25% off coupon and picked up a Harbor Freight Mini Mill.  Lots of info about these online and they get decent reviews. Hard to go wrong for under $600 delivered.  Now accumulating the necessary tooling from HF and LittleMachineShop.com.  I'm a machinist newbie but have ordered some books and am looking forward to playing around with this.


Please document in a thread! Are you using an off the shelf servo kit? I know this stuff is covered plenty on cnc boards, but that is a whole new as you say rabbit hole to have to dive into also.
 

Offline chriswebb

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Re: What did you buy today? Post your latest purchase!
« Reply #5085 on: December 17, 2017, 02:54:30 am »
Picked up another Keithley 2015 off of ebay for a decent price to add to the one I got for 250 and hedge my bet since I am so unsure of that other one.
Always learning. The greatest part of life is that there will always be more to learn.
 

Offline bitseeker

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Re: What did you buy today? Post your latest purchase!
« Reply #5086 on: December 17, 2017, 04:29:14 am »
Ooh, that looks like fun, mtdoc!

Ha! we'll see.  I'm quickly realizing that there's a whole new rabbit whole to fall into with these mini mills......

Yes, it seems just about everything becomes a whole new rabbit hole. Enjoy your new Wonderland!
I TEA.
 

Offline Inverted18650

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Re: What did you buy today? Post your latest purchase!
« Reply #5087 on: December 17, 2017, 04:45:20 am »
Arrived today. Power Designs Model 5005R. 20VDC up to 500mA. A quick test was very promising for eBay score, for just $23 shipped.
« Last Edit: December 17, 2017, 05:25:59 pm by Inverted18650 »
 

Offline Inverted18650

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Re: What did you buy today? Post your latest purchase!
« Reply #5088 on: December 17, 2017, 04:49:03 am »
Picked up another Keithley 2015 off of ebay for a decent price to add to the one I got for 250 and hedge my bet since I am so unsure of that other one.

I have seen several lately, what seller are you visiting for the 2015 or are you shopping around? Ive a couple vendors with more than one in stock right now, sold "as-is" and "unable to test."

Offline chriswebb

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Re: What did you buy today? Post your latest purchase!
« Reply #5089 on: December 17, 2017, 05:11:23 am »
Picked up another Keithley 2015 off of ebay for a decent price to add to the one I got for 250 and hedge my bet since I am so unsure of that other one.

I have seen several lately, what seller are you visiting for the 2015 or are you shopping around? Ive a couple vendors with more than one in stock right now, sold "as-is" and "unable to test."

It was from a seller with a single unit sold as used with a few other items (not a reseller or anything.) Found them while I was searching for 11730A cable. 100% feedback and enough responses for me to trust them.  I have received one of those $250 USD (with that sweet $50 shipping surcharge) ones that was sold as-is, and it seems to work on my cursory inspection (readings are ball park, but I haven't had anytime to really examine it deeply). This one was not much more, and I am able to return it since it was sold as used.  Going to use this new unit to compare with the other, and possibly use the cheaper one as parts for the newer one if I find it's not performing properly. 
Always learning. The greatest part of life is that there will always be more to learn.
 
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Offline bitseeker

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Re: What did you buy today? Post your latest purchase!
« Reply #5090 on: December 17, 2017, 05:17:01 am »
Arrived today. Power Designs Model 5005. 20VDC up to 500mA. A quick test was very promising for eBay score, for just $23 shipped.

Wow, nice score for $23.
I TEA.
 
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Offline Cubdriver

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Re: What did you buy today? Post your latest purchase!
« Reply #5091 on: December 17, 2017, 05:47:59 am »
I ordered an HP 3444A DC Multifunction unit to put in one of my 3440As that presently has only an autoranging DC plug in.  I'll happily trade DC-V autoranging for the addition of DC current and resistance measurement capability.

This is the one I presently have:


And this is what the new one will go in place of:


-Pat
If it jams, force it.  If it breaks, you needed a new one anyway...
 

Offline julianhigginson

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Re: What did you buy today? Post your latest purchase!
« Reply #5092 on: December 17, 2017, 09:36:56 am »
Picked up another Keithley 2015 off of ebay for a decent price to add to the one I got for 250 and hedge my bet since I am so unsure of that other one.
But if they disagree, how will you know which is most correct? Sorry, but get back on eBay... you're going to need a third! :scared:
« Last Edit: December 17, 2017, 06:59:40 pm by julianhigginson »
 

Offline Decoman

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Re: What did you buy today? Post your latest purchase!
« Reply #5093 on: December 17, 2017, 10:20:38 am »
So.. on Friday I placed an order on eBay for a $19 black sheep leather jacket with free shipping (free shipping from USA of all places), and so.. now eBay today sent me a message claiming that the sellers account had been abused by some unauthorized access or something like that, and that the listing was in error. Paypal have my money listed as "pending transaction" but there is NO WAY to stop it. I have now had to send Paypal a written message, in the hopes of them canceling my pending payment. I was given an email address to try contact the seller, and so I did use that option, but I can't help but wonder if maybe the seller's email address itself is compromised. I wonder if perhaps the seller just typed in the wrong details in his sales ad. Though, looking at the sellers activity, there had been no activity for his sales in months, until just recently.

Moral of the story: If it is too good to be true, it probably is. :|

Damnit, it was a really nice looking leather jacket. :| And apparently some 300 other ppl as well also thought that.
« Last Edit: December 17, 2017, 01:08:21 pm by Decoman »
 

Offline Specmaster

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Re: What did you buy today? Post your latest purchase!
« Reply #5094 on: December 17, 2017, 10:28:58 am »
Picked up another Keithley 2015 off of ebay for a decent price to add to the one I got for 250 and hedge my bet since I am so unsure of that other one.
But if they disagree, hire will you know which is most correct? Sorry, but get back on eBay... you're going to need a third! :scared:
No way, you're going to need at least 4 and then take the average if the readings and for accuracy, get more meters, it's simple. [emoji28]
Who let Murphy in?
 
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Offline TX-RX

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Re: What did you buy today? Post your latest purchase!
« Reply #5095 on: December 17, 2017, 01:29:39 pm »
Scored an old school Eastern European P4085 resistor standard (1 GOhm, 10 GOhm, 100 GOhm and 1000 GOhm) on ebay. Actually, it's a resistor "imitator", as from 10 GOhm onwards the measurement reading on the meter is generated through a voltage divider. Given that it was built in 1982 it still seems to be pretty accurate.

 

Offline edgelog

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Re: What did you buy today? Post your latest purchase!
« Reply #5096 on: December 17, 2017, 02:01:06 pm »
1 Tohm at 200 V ought to give 200 pA, but I see 20 pA on the Keithley. How come?
 

Offline Twoflower

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Re: What did you buy today? Post your latest purchase!
« Reply #5097 on: December 17, 2017, 02:05:49 pm »
I think looking at the display: "R > LIMIT" gives a hint ;-) Also "Limit: 999.9GOhm" another.

Also The measurement has been finished. So the Megohmmetre does not apply the 200V any more.

And another edit: Be careful. The nominal voltage is 100V not 200V.
« Last Edit: December 17, 2017, 02:09:55 pm by Twoflower »
 

Offline TX-RX

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Re: What did you buy today? Post your latest purchase!
« Reply #5098 on: December 17, 2017, 02:09:43 pm »
The Keithley 487 is just used as an external voltage source for the megaohm meter. Otherwise there is no input connected so it's just showing some random reading that can be disregarded.

Moreover, the limit 999.9 GOhm does not have any effect on the reading. It is just an arbitrary threshold value in order to categorize resistors as "good" or "bad".
 

Offline kalel

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Re: What did you buy today? Post your latest purchase!
« Reply #5099 on: December 17, 2017, 03:20:26 pm »
Arrived today. Power Designs Model 5005. 20VDC up to 500mA. A quick test was very promising for eBay score, for just $23 shipped.

Looks great.
 
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