EEVblog #677 - Mailbag

[EEVblog]

Mailbag Monday
Dave opens his mail.


Spoilers & Links:
HP 4260A LCR Universal Bridge
http://cp.literature.agilent.com/litweb/pdf/04260-90011.pdf
iPod Blood pressure monitor
Old computer hardware
Intel 1Mb Bubble Memory
PICop development board: http://www.bloguetronica.com/2014/07/placa-de-desenvolvimento-picop.html
TEM Products SMD IC and LED thermal products
PowerPeg: http://tem-products.com/index.php/powpeg.html/
Stepper Motor Controller: http://tem-products.com/index.php/motion-control.html
TSL1401CL LineScan Camera https://www.tindie.com/products/AP_tech/tsl1401cl-linescan-camera-/

[mux]

I'll just pre-emptively, before even watching the video, complain that the video is too short so that that's over with. We all know somebody is going to say it, might as well be me.

Alright, let's see what's what and who's who! *switches to the video*

[max666]

Awww no postcards any more, I liked watching the postcards. The format is called mailbag after all.
Impossible to please everybody, isn't it Dave?

[Pedram]

these Thermal Connectors are nice
but they are overpriced. $1.4 each ?? too expensive.

[simingx]

Hi Dave, I see you've finally gotten around to opening my package 

The 4260A did work once upon a time, but it's been sitting around way too long... guess the years finally took their toll on it

I don't remember the Mode and Range dials being out of alignment though, guess it got bashed around somewhat in transit...

Hope to see the teardown video soon, I know you'll love it  O0

[German_EE]

Those power pegs are an interesting idea, I have never been a fan of multiple vias on a PCB installed underneath a chip in an attempt to promote heat flow. One thing though, with the power peg installed in the hole how do I solder the chip to the board/peg?

[SeanB]

I ould guess if you are reflowing it you make the power peg a press fit, and install it with a jig before solder past application, probably using a spacer that holds it while supporting the board. Then the paste is applied over it, and then place and reflow as normal and it will wick into the hole and the component. You probably would be better off though having the board side not being a round pin, rather a polygon shape so that you can press fit it into a controlled range of hole diameters and which allows solder to wick through the holes during reflow. You probably would also want some dimpling on the mounting shoulder for the same reasons, so that hot gas and trapped flux can escape before the solder wicks through to hold it. That probably would be easy to do with a die set that forges the part out of a slug cut from rod, and then you do the machining in a CNC to get the end flat and do the thread for the screw. After that you wash, tumble polish then do the plating to protect them.

[wilgil]

That 4 input 'scope behind Dave is still upside down...my OCD is killing me....
Maybe he could gift it to a good home (I have a suggestion) where it will be cared for and put the correct way up on said good home's workbench... 

[eV1Te]

I really like the Power Pegs, I will definitely have them in mind the next time I am considering though hole TO220s or similar with a standing heat-sink.

As I understand you screw the heat-sink into the peg after everything has been soldered. But since they are tiny, how much momentum can you use on the screw? How do you prevent the screw from shaking loose (Loctite?)?

[DrSchweizer]

Just some additional information on Eritrea. It is ruled by Isayas Afewerki a former guerilla fighter, dictator and head of the only allowed party. The country was founded 1993 and is also called 'Africa’s North Korea'. The UN actually rates it as worse than North Korea. So not a place to go to.

[jancumps]

That 4 input 'scope behind Dave is still upside down...my OCD is killing me....
...

That's because he lives in Australia. I'm from Belgium, Europe. The scope is showing correct for me....

[Dave]

Those thermal pegs are quite nice, but one thing concerns me about them: Can the solder joints withstand the mechanical stress created by those pegs? Imagine you have 6-10 transistors on a board, all connected to the same heatsink, each with its own powerpeg. The heatsink will certainly have a different thermal expansion coefficient than FR4 - something will have to give.

[EEVblog]

Just some additional information on Eritrea. It is ruled by Isayas Afewerki a former guerilla fighter, dictator and head of the only allowed party. The country was founded 1993 and is also called 'Africa’s North Korea'. The UN actually rates it as worse than North Korea. So not a place to go to.

Yikes 

[EvilGeniusSkis]

Dave you pronounced Eritrea correctly, I've got a friend on the Eritrean ski team (alpine skiing).

[Rutger]

Dave, in the previous mailbag (or the one before) you received an cool EEVBlog clock. Can you please hang the clock on the opposite wall of the web cam (above the small desk), so the world can see the local time and live action. 

[Bud]

...The UN actually rates it as worse than North Korea. ..

And people of both Eritrea and North Korea just live their lives and do not give a f@ck about UN ratings.

[Bud]

Those thermal pegs are quite nice, but one thing concerns me about them: Can the solder joints withstand the mechanical stress created by those pegs?

I agree, would also be concerned about the mechanical stress on the die if the peg is soldered to an IC. 

[Bud]

I have never been a fan of multiple vias on a PCB installed underneath a chip in an attempt to promote heat flow.

Why is that? Works for me very well.

[Bored@Work]

That 4 input 'scope behind Dave is still upside down...my OCD is killing me....

You don't understand. That is Dave's canary. As long as it is upside down everything is ok. If the oscilloscope is suddenly upright we know that Dave is held hostage by Ben Heck and we need to send in the clowns to rescue him.

[nitro2k01]

And people of both Eritrea and North Korea just live their lives and do not give a f@ck about UN ratings.

While they may not care about the ratings themselves, they would certainly care about the poverty, starvation and political oppression that prompted those ratings in the first place.

[Smokey]

...The UN actually rates it as worse than North Korea. ..

And people of both Eritrea and North Korea just live their lives and do not give a f@ck about UN ratings.

That is an interesting opinion.  Did you enjoy being able to express your opinion publicly?  Maybe you can explain to the people of Eritrea what it's like to be able to express yourself without the risk of going to jail forever. 

http://en.wikipedia.org/wiki/Eritrea
"in September 2001 the government closed down all of the nation's privately owned print media, and outspoken critics of the government have been arrested and held without trial, according to various international observers, including Human Rights Watch and Amnesty International. In 2004 the U.S. State Department declared Eritrea a Country of Particular Concern (CPC) for its record of religious persecution."

..... yes I apologize for quoting wikipedia...

[EEVblog]

Dave, in the previous mailbag (or the one before) you received an cool EEVBlog clock. Can you please hang the clock on the opposite wall of the web cam (above the small desk), so the world can see the local time and live action.

Ah, I want to get my Time Circuit clock working again for that, thanks for the reminder.

[Towger]

Is that the BTTF clock to which you are referring? Again? 
I wasn't intending to mention it (again) for another 50 weeks.

Fitted to the C5 ;-)

[JackOfVA]

I have a 4260A and the similar General Radio analog RLC meter (1650A and also a 1650B) in my collection, along with both GR and HP digital RLC meters.

There's still a place for the analog instruments, however, compared with the inexpensive digital meters in that (a) external voltage bias for capacitance measurement and current bias for inductance can be applied and (b) it is possible to vary the AC voltage applied to the part under test.

The 4260A unfortunately limits external bias voltage to 6V but the GR meters can use external bias up to 30V or perhaps higher -- it's been a while since I looked at the manual. And the 1650B permits DC current to be passed through the inductor under test as well, up to 50 mA or so.  The 1650B also has a front panel potentiometer that adjusts the applied AC voltage.

While lab grade digital RLC meters permit external bias and adjustable drive (although some make this an extra cost option), these features are not often found on the simpler RLC meters.

[Excavatoree]

That 4 input 'scope behind Dave is still upside down...my OCD is killing me....
Maybe he could gift it to a good home (I have a suggestion) where it will be cared for and put the correct way up on said good home's workbench... 

I think Dave has explained that he doesn't want the electrons to leak out.

It's for us Northern Hemisphere folks.  From our perspective, it's the only scope in his lab that's NOT upside down.

[Rutger]

Ah, I want to get my Time Circuit clock working again for that, thanks for the reminder.

The BTTF clock sounds cool, but I don't think we will be able to read the digits from that distance an analog clock would better.

[womai]

I did a short search and it seems the 4260A is more like 1966 vintage, not from the 80s.

http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1966-09.pdf

IMHO that fits the overall design of the unit, just looks the way they did it in the 60s.

[EEVblog]

I did a short search and it seems the 4260A is more like 1966 vintage, not from the 80s.
http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1966-09.pdf
IMHO that fits the overall design of the unit, just looks the way they did it in the 60s.

Yeah, that feels right to me. I was going by the date in the manual. The 80's is when they must have archived it.

[arekm]

For Cree LEDs it's better to use copper plates (+ small isolation) instead of typical pcb and "power pegs".

Example, noctigons, sinkpads, maxtoch:

http://budgetlightforum.com/node/21547

http://budgetlightforum.com/node/33488

[TEMProducts]

Hello everyone! A few responses here...

Those power pegs are an interesting idea, I have never been a fan of multiple vias on a PCB installed underneath a chip in an attempt to promote heat flow. One thing though, with the power peg installed in the hole how do I solder the chip to the board/peg?

The pegs do not press fit. This would cause stress in the FR4. They slip-fit in a 2.5MM via.

Simply add a dab of flux, tack in place, allow to cool, and paste/reflow as usual. Action of capillarity holds the peg in place when the solder is molten.

I will try to make a video soon.

I really like the Power Pegs, I will definitely have them in mind the next time I am considering though hole TO220s or similar with a standing heat-sink.

As I understand you screw the heat-sink into the peg after everything has been soldered. But since they are tiny, how much momentum can you use on the screw? How do you prevent the screw from shaking loose (Loctite?)?

1.0 inch pounds of torque MAX. Use a clutch driver, or screw by hand.

http://tem-products.com/TCAP-4325-TR_Datasheet.pdf

As long as the screw is fully engaged in the Peg, the screw will actually break before the thread strips. 0-80 screws are delicate!

PowerPeg is made of copper, so friction is enough to hold the screw in place when fully tightened. I have never seen one come loose (and I have used them in every way imaginable  ). However loctite can be used, and does not effect the thermal interface.

Additional screws from PCB to heatsink are recommended to relieve mechanical stress from the thermal connector. PowerPeg is tough, but not invincible!

Those thermal pegs are quite nice, but one thing concerns me about them: Can the solder joints withstand the mechanical stress created by those pegs? Imagine you have 6-10 transistors on a board, all connected to the same heatsink, each with its own powerpeg. The heatsink will certainly have a different thermal expansion coefficient than FR4 - something will have to give.

The effects of thermal expansion of copper are negligible over short distances. For example: with a temperature change of 100C the length of the peg will change 0.000068 inches.

PowerPeg is precision machined to have matched thickness allowing many pegs to be attached to a single heatsink.

these Thermal Connectors are nice
but they are overpriced. $1.4 each ?? too expensive.

In the past two years we have made only one batch of 1200 pegs. The small quantity is the reason for the high price.

These pegs were (partially) hand made. They are precision  machined from copper alloy and plated with nickel, then 24 kt gold.

The next batch will be larger. I forsee the price under $0.80.

[JuiceKing]

The HP 4260A is an amazingly compact and convenient analog bridge. Direction lights tell you which way to crank and it automatically finds D and Q. I believe it was the first product from the YHP group and they poured a lot of passion into it. Check out the HP Journal article that came out when it was launched.


Sent from my iPad using Tapatalk HD

[simingx]

The HP 4260A is an amazingly compact and convenient analog bridge. Direction lights tell you which way to crank and it automatically finds D and Q. I believe it was the first product from the YHP group and they poured a lot of passion into it. Check out the HP Journal article that came out when it was launched.


Sent from my iPad using Tapatalk HD

Linked for your convenience

www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1966-09.pdf

The HP Journals make very good reading... the theory of operation is described in much detail, rather than nowadays where it is just given a cursory description, as everything is done in software

[TheWelly888]

Dave - I work on blood pressure monitors as part of my job in the local hospital so I would like to point out that they do not use "vacuum pumps" as you described it, they are actually compressors to inflate the cuff, the air is then released slowly ( at a set rate of about 5 - 10 mmHg per second ) through a slow release valve.

I'm looking forward to the teardowns of the gear.

[TEMProducts]

This video shows how PowerPeg thermal connectors integrate easily with typical PCB assembly techniques.

Simply tack the peg in place, stencil, and re-flow as usual. Capillary action holds the peg in place while the solder is molten.

[EvilGeniusSkis]

Dave, in the previous mailbag (or the one before) you received an cool EEVBlog clock. Can you please hang the clock on the opposite wall of the web cam (above the small desk), so the world can see the local time and live action.

Ah, I want to get my Time Circuit clock working again for that, thanks for the reminder.

I'm surprised no one has sent you the chips yet.

[TEMProducts]

Anyone who was interested in the The PowerPeg thermal management system, it is entered in the 2015 Hackaday contest.

Theres tons of interesting information on the project page.

https://hackaday.io/project/6874