EEVblog #546 - Mailbag Monday - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: November 11, 2013, 12:01:28 am
content: TekBox Digital Solution Open Source Hardware Kit for an EMC conducted emissions compliance Line Impedance Stabilisation Network (LISN)http://www.tekbox.net/open-hardware/tboh01-5uh-impedance-stabilisation-network-lisnhttps://www.youtube.com/user/chrmoeBinary Epoch Clock Kit:http://maniacallabs.com/product/becv1/Learning to fly with Eagle V6 book:http://www.elektor.com/products/books/electronics/eagle-v6-getting-started-guide.2453009.lynkxPIC Microcontroller Programming: in 10 captivating lessons:http://amzn.to/1fuMlrwPIN Diode Radiation Counter kit:http://www.elektor-magazine.com/us/magazine-contents/article.html?tx_elektorarticle_list=3963&tx_elektorarticle_list=showPCB kit construction.!Private video

author: c4757p
author_rank: Super Contributor
timestamp: November 11, 2013, 12:10:31 am
content: That second phone (grey one) is really Australian? My grandmother used to have one that was identical (or very close) in her office here in the U.S.

author: nathanpc
author_rank: Unknown
timestamp: November 11, 2013, 12:44:24 am
content: Looking forward to the LISN test video.Hmm interesting... You've assembled a kit this time, is this going to become a common thing? I really liked the fact that you assembled it, in my opinion it adds more value to the mailbag videos.

author: EEVblog
author_rank: Unknown
timestamp: November 11, 2013, 01:41:38 am
content: Quote from: nathanpc on November 11, 2013, 12:44:24 amIt's already shot, and so is the phone teardown, so they are the next two videos.QuoteIf I have time. This one didn't take long, and I had some spare time this time around, but often I don't.

author: kizzap
author_rank: Unknown
timestamp: November 11, 2013, 01:56:23 am
content: Oh Lordy, that Telstra phone is a blast from my recent past. Unfortunately I used to work in a Telstra call centre (directory assistance only thankfully), and every work station had one of those at the workstation. However all the phones seemed to plug into the computers, and then we used another different box to connect our headsets to. Got to love the backwardivity of Telstra.Come to think about it, we were plugging straight into that phone when we were using the old software. This software would have easily been 30 years old (ms-dos based software) that would consistently crash without any indication that anything was going on, and we put it down to the fact that the newer PCs that were running the software weretoo fastfor the software, thus causing issues. However Telstra got rid of that old software roughly two years ago, and either outsourced parts of that service overseas, or completely automated the systems so that you would never get an operator (and believe me, some people needed the operator).-kizzap

author: Rufus
author_rank: Super Contributor
timestamp: November 11, 2013, 02:07:00 am
content: Quote from: EEVblog on November 11, 2013, 12:01:28 amMaybe someone more expert EMC wise will comment but the LISN stuff looks misleading to me.Single channel LISNs are 3 terminal devices, in, out, and ground with ground usually being the metal case of the LISN bolted/strapped to the ground plane.The unit and information implies you can just power the unit under test through it. You need to provide a defined impedance on the power return as well and it contributes to conducted emissions. Only when the unit power return is intended to be through the 'chassis' and is connected directly to the ground plane can you get away with a single channel LISN.For most equipment you would require two of these and if the power connection is considered to be a single cable a balun to get a common mode signal from the combined outputs.edit: some kind of transformer not a balun I think.

author: johnboxall
author_rank: Unknown
timestamp: November 11, 2013, 02:29:52 am
content: Quote from: c4757p on November 11, 2013, 12:10:31 amPretty sure it's a common Alcatel-designed system that was made locally under licence here for Telstra.The clock kit is fun:http://tronixstuff.com/2013/09/15/kit-review-maniacal-labs-epoch-clock/

author: Stonent
author_rank: Super Contributor
timestamp: November 11, 2013, 03:42:01 am
content: I've seen those phones in the US. They were popular in the late 90's early 2000's.As far as I know the Cisco phone is still current. And the odd module that you didn't know what it was for is a speed dial module that goes onto the side of a phone. Those seem to be common with receptionists/assistants/secretaries where they call a lot of the same people repeatedly throughout the day.

author: bktemp
author_rank: Super Contributor
timestamp: November 11, 2013, 06:26:27 am
content: The photodiode on the radiation counter must be shielded to avoid any light shining onto it. Otherwise the amplifier will either oscillate or get saturated.Tot get the best sensitivity it is also wise to electrically shield the sensor board.Just put the whole board together with the radioactive material in a closed metal case or wrap the sensor with aluminium foil.

author: Noah
author_rank: Newbie
timestamp: November 11, 2013, 03:16:23 pm
content: Wow it would be really great, if you do a video on EMI stuff! We have a dedicated EMI labratory in our company and if I new more about EMI i could play around with my circuitsThanks for your work!

author: gardner
author_rank: Regular Contributor
timestamp: November 11, 2013, 06:36:01 pm
content: Stand-offs:I keep a couple of metres of 5mm polythene tubing and a box of 3mm and number-6 nylon nuts and bolts on my bench. When I need stand-offs, I just chop lengths of tubing to suit. It's great for prototyping.

author: JackOfVA
author_rank: Unknown
timestamp: November 11, 2013, 09:52:49 pm
content: DMS switch -- is Nortel's acronym for "Digital Multiplex System" -- Nortel's digital telephone switches were given identifiers with a DMS prefix such as DMS 100 or DMS 500.Nortel's DMS switches were used in both telephone company central office applications and also as private branch exchange (PBX) switches. Nortel's smaller PBX offerings also had names, such as Meridian, although the Meridian was, as I understand it, based on scaled down DMS technology.Before Nortel went spectacularly bankrupt, it had a solid reputation in the PBX market, as well as for telephone central office and cellular radio switching (with the DMS platform). My clients bought hundreds of millions of dollars of Nortel's DMS 100 switches and radio equipment over the years and were pleased with the performance.As I understand it, Nortel's interface between the digital PBX and the telephone instruments is TDM, but it's proprietary, not the standard telephony 64 kb/s version, or even the 2B+D ISDN flavor of TDM, but I could well be mistaken here as all my dealings with Nortel were in the cellular radio switching and base station fields and I never had reason to dig into the PBX technology.

author: JOERGG
author_rank: Contributor
timestamp: November 12, 2013, 02:37:56 am
content: Cutting the leads after soldering is not wise, because the solder can crack. Beyond that you will want the solder to cover the cut surface in order to prevent corrosion.

author: steve1515
author_rank: Regular Contributor
timestamp: November 12, 2013, 02:39:33 am
content: Does anyone have any info on those nice electronic load banana jack cables?

author: Bored@Work
author_rank: Super Contributor
timestamp: November 12, 2013, 05:50:21 am
content: Quote from: JOERGG on November 12, 2013, 02:37:56 amYes - if you do high reliable stuff for space, aeronautics, militate or whatever. For amateur stuff like an Elektor kit it really doesn't matter. For decades amateurs and even pros cut leads after soldering because it usually doesn't matter.

author: Stonent
author_rank: Super Contributor
timestamp: November 12, 2013, 07:08:48 am
content: Quote from: Bored@Work on November 12, 2013, 05:50:21 amI had my Radio Shack (made by Metex) multimeter apart yesterday to see about replacing the small fuse and, there's a 40Pin DIP in there that has all the leads cut almost perfectly flat with the board.Sometimes if I have a particularly blobby solder spot that I caused, I'll go down a little into the solder with the cutters and then retouch the iron to it to get it down. Probably my real problem is I need some flux to use instead of just relying on the solder rosin.

author: k2teknik
author_rank: Regular Contributor
timestamp: November 12, 2013, 08:37:04 am
content: Quote from: Bored@Work on November 12, 2013, 05:50:21 amIt matters, but not "right here, right now" so to speak.It matter over time, some years, how many depend on many factors mostly material, temperature and environment.It is a bad habit to cut after soldering, better get it in you backbone not to work in that way.And if you are that much short on time that you simply do not have the time to do it right, well then you are most likely doing a shitty work anyway.When I was a trainee our supervisor/teacher was always nagging on us about this issue "Do not cut after soldering", and they did it for a reason "quality work".

author: peter.mitchell
author_rank: Super Contributor
timestamp: November 12, 2013, 10:45:41 am
content: How do you think they do it in commercial applications with through hole wave soldering? Cut every component to length before soldering? Not a snowflake's chance in hell. It goes through the wave soldering machine, then it goes throguh a trimmer like thiswhich is basically just a big spinning disc a predefined distance below the board which cuts off the leads.

author: k2teknik
author_rank: Regular Contributor
timestamp: November 12, 2013, 12:12:49 pm
content: Quote from: peter.mitchell on November 12, 2013, 10:45:41 amThen I had been working in hell, we did cut every component to length before soldering, and the reason was not to stress the solder joint and close the copper exposed when you cut a pin.QuoteI been working in a place where they did that too, expensive high end HiFi / TV gear, but they only did it in that way for some years until they got machinery that could blend the pins and cut in one process, It is not without problems to wave solder when the components has long legs.

author: creyc
author_rank: Regular Contributor
timestamp: November 12, 2013, 02:29:30 pm
content: Quote from: JOERGG on November 12, 2013, 02:37:56 amI can understand how this may stress a solder joint if you are rough with your cutting technique or are using dull flush-cutters but how else would you be able to assemble a through-hole PCB? I would think trimming your leads before soldering would cause components to fall out since there would be no more pin left to hold the component in place?

author: MartinX
author_rank: Regular Contributor
timestamp: November 12, 2013, 04:25:30 pm
content: Where I work most component leads are cut to the right length before being mounted, by us or by the component supplier, if you are using a wave soldering machine and the leads are already cut there is no need to flip the board over so the components stay in their place.

author: k2teknik
author_rank: Regular Contributor
timestamp: November 12, 2013, 05:01:43 pm
content: Quote from: creyc on November 12, 2013, 02:29:30 pmWith the right assemble technic and support gear no problem. You can bend the pins so the component can't fall out of the hole, or you can support the component during cutting so it stays in position (when the PCB is upside down) during cutting, turn the PCB over and remove the support before wave soldering or you may hand solder just after cutting with the support in place.

author: FrankBuss
author_rank: Unknown
timestamp: November 12, 2013, 05:57:59 pm
content: JAL looks suspiciously similar to Pascal, but without the confusing semicolon rules. I never liked it when I had to use Turbo Pascal in school when I was a young. Fortunately it was possible to write inline assembler.

author: creyc
author_rank: Regular Contributor
timestamp: November 12, 2013, 06:20:26 pm
content: Quote from: k2teknik on November 12, 2013, 05:01:43 pmQuoteI see we're talking production PCB assembly and hobbyist kit assembly in the same framework here.I suppose the point was worth mentioning, but in lieu of having access to production-level assembly equipment, I think this is one point most hobbyists can safely ignore while assembling their kits.

author: k2teknik
author_rank: Regular Contributor
timestamp: November 12, 2013, 07:19:59 pm
content: Quote from: creyc on November 12, 2013, 06:20:26 pmSorry, but in my world there is not much difference.QuoteHobbyists (as well as pros) can easily make the own support tools, it is not rocket science or expensive in any way.

author: tcleavela
author_rank: Contributor
timestamp: November 12, 2013, 07:42:52 pm
content: Quote from: FrankBuss on November 12, 2013, 05:57:59 pmLooks like they swapped the semicolon rules for the infamous C-style assignment and equality operators.

author: Vasi
author_rank: Regular Contributor
timestamp: November 14, 2013, 09:31:04 pm
content: Hi Dave, is there a reason why my comment is not moderated on your blog? Should I post it here, or should I forget about? Anyway, no big problem but I would liked to know where and what I did wrong...

author: olsenn
author_rank: Frequent Contributor
timestamp: November 18, 2013, 02:55:16 am
content: Anybody know where I can pick up one of those cables for converting the screw terminals on the e-load to female banana jacks? Or a similar (high quality) product if that one is custom made for Dave

author: Unknown
author_rank: Unknown
timestamp: November 18, 2013, 07:47:12 am
content: A spade lug to banana jack adapter likethismight work (I haven't checked the dimensions of the terminals on the load). I'm sure you can also find commercially manufactured spade lug to banana leads.