Author Topic: EEVblog #680 - Mailbag  (Read 16365 times)

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Offline EEVblog

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EEVblog #680 - Mailbag
« on: November 04, 2014, 11:03:03 am »
Mailbag Monday
Flux Capacitor T-Shirts: http://teespring.com/stores/eevblog
How NOT to blow up your oscilloscope (Isolation & Grounding):

How a Microwave Magnatron Works
PCB Holder
Magazine Memories
Memory Stacks
Isolated USB-RS232 Interface
LGB Model Train Controller & Decoder
Caterpillar Dump Truck Controller

2114 SRAM Memory: http://www.princeton.edu/~mae412/HANDOUTS/Datasheets/2114.pdf

« Last Edit: November 04, 2014, 11:37:03 am by EEVblog »
 

Offline klinkerstein

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Re: EEVblog #680 - Mailbag
« Reply #1 on: November 04, 2014, 12:12:48 pm »
Scan of "Engineer is a loner" and the next chapter please  ;D ;D
 

Offline Tandy

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Re: EEVblog #680 - Mailbag
« Reply #2 on: November 04, 2014, 12:18:17 pm »
Yes RadioShack are on life support.

Their share price is now below $1 and they almost went under until one of their share holders Standard General did a deal that managed to get them re-financed. The problem is the deal is short term and if RadioShack does not improve profitability by next year then the loans will be called in.

It is highly unlikely that RadioShack will be able to turn it round and most financial experts believe it will be out of business by the summer next year.
For more info on Tandy try these links Tandy History EEVBlog Thread & Official Tandy Website
 

Offline max666

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Re: EEVblog #680 - Mailbag
« Reply #3 on: November 04, 2014, 12:41:14 pm »
Careful when disassembling a magnetron, the ceramic insulator stems most likely contain beryllium. So do not cut or grind those pinkish ceramics, because dust of beryllium containing ceramic can be quite toxic.
 

Offline bktemp

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Re: EEVblog #680 - Mailbag
« Reply #4 on: November 04, 2014, 12:51:59 pm »
Careful when disassembling a magnetron, the ceramic insulator stems most likely contain beryllium. So do not cut or grind those pinkish ceramics, because dust of beryllium containing ceramic can be quite toxic.
This is beeing discussed frequently in forums. Most discussions end with the fact that beryllium make no sense as an insulator in a magnetron, because beryllium oxide is used whenever a good thermal conductor, but electrical insulator is needed. And this is not necessary in a magnetron, because the resonator cavity made out of copper is directly mounted inside the heatsink without any insulation.
 

Offline Gibol

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Re: EEVblog #680 - Mailbag
« Reply #5 on: November 04, 2014, 01:36:56 pm »
Please scan the magazines in your spare time. I would like to take a better look at that. I've spotted the article about BBC experimenting with digital television... wow - in 1974!
 

Online Rasz

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Re: EEVblog #680 - Mailbag
« Reply #6 on: November 04, 2014, 02:00:53 pm »
magnetron dangerous you say?



Who logs in to gdm? Not I, said the duck.
My fireplace is on fire, but in all the wrong places.
 

Offline Hade

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Re: EEVblog #680 - Mailbag
« Reply #7 on: November 04, 2014, 02:42:03 pm »
Had a chuckle about your kid watching train videos all day.
My little boy went through that exact same phase.
I'm always saying how crazy the viewing figures are on those videos.
There's literally videos of a kid playing with a toy train that have 30 million views!

My daughter's now doing the same thing watching people unbox small toys. I've commented to my wife how similar they are to your mailbag videos!
 

Offline CJWarlock

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Re: EEVblog #680 - Mailbag
« Reply #8 on: November 04, 2014, 04:49:11 pm »
About the RAM stack. The +60K RAM Expansion developed by Mr. Fiz (of Samar, a demoscene group) for the Commodore C64 computer was designed to be done this way. Two additional memory chips were stacked onto already mounted ones with only CAS pins lifted up and wire-connected to some other logic chips (address decoders and so on) which had only +5V and GND pins soldered onto already existing logical chips (and other pins were lifted up and wire-connected to other chips). Here's the description and scheme: csdb.dk/release/?id=110815?. So, stacking chips was a pretty common and easy solution to modify 8-bit computers. :)
 

Offline craigh

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Re: EEVblog #680 - Mailbag
« Reply #9 on: November 04, 2014, 06:46:36 pm »
Yup, I remember the Intelec8.  Used one to burn (sometimes literally!) EPROMS back in 1979 while I was doing some development with the 'new' 8085 microprocessor.  Did the editing and assembly on an HP21-something mini-computer which spit out the HEX file onto a paper tape.  Took the tape to a Teletype machine hooked up to the Intelec to read in the code and burn the EPROM (256 byte if I remember correctly, or did we have the new 1k byte versions?).  Wow, have we come a long way since then.
 

Offline gemby

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Re: EEVblog #680 - Mailbag
« Reply #10 on: November 04, 2014, 07:29:37 pm »
And yes, big thumbs up for Way back Wednesday idea :-+
 

Offline Fungus

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Re: EEVblog #680 - Mailbag
« Reply #11 on: November 04, 2014, 07:49:59 pm »
You gotta scan that magazine, whatever it takes.

You don't need a flatbed scanner these days, just set up a decent camera and photograph each page as you turn them.

Do left side, move magazine across table, do right side, turn page. Use a foot pedal to take the pic.

Pay a passing student $5 to do it, whatever it takes...

 

Offline elgonzo

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Re: EEVblog #680 - Mailbag
« Reply #12 on: November 04, 2014, 08:16:05 pm »
Dave, did my old eyes just see an 8-inch floppy disk on your shelf there?
Also, i spotted a few males. I think they're winners...  ;D  or not...  >:D
« Last Edit: November 04, 2014, 08:58:47 pm by elgonzo »
 

Offline jancumps

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Re: EEVblog #680 - Mailbag
« Reply #13 on: November 04, 2014, 08:33:44 pm »
I thought it was New Order's Blue Monday maxi...
 

Offline Yago

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Re: EEVblog #680 - Mailbag
« Reply #14 on: November 04, 2014, 09:24:28 pm »
Scan of "Engineer is a loner" and the next chapter please  ;D ;D

Ohhh yessss!!!! :D
 

Offline Fungus

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Re: EEVblog #680 - Mailbag
« Reply #15 on: November 04, 2014, 09:38:19 pm »
Scan of "Engineer is a loner" and the next chapter please  ;D ;D

Ohhh yessss!!!! :D

He can't leave us hanging on that one, can he???  :scared:
 

Offline Yago

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Re: EEVblog #680 - Mailbag
« Reply #16 on: November 04, 2014, 09:46:13 pm »
Scan of "Engineer is a loner" and the next chapter please  ;D ;D

Ohhh yessss!!!! :D

He can't leave us hanging on that one, can he???  :scared:

Thing is, I'm still hoping for some good tips in it ! ;) :D
 

Offline electrocat

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Re: EEVblog #680 - Mailbag
« Reply #17 on: November 04, 2014, 10:24:30 pm »
Hi
Thanks for the PCB holder review
There are groves top and bottom to keep the board from droping down.
Made some up there for sale on
https://www.tindie.com/products/Z2instro/pcb-assembly-holder/?pt=directsearch

Regards
Leo
 

Offline eV1Te

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Re: EEVblog #680 - Mailbag
« Reply #18 on: November 04, 2014, 10:29:39 pm »
Dave, could you please link to the USB-RS232 converter website? I might want to purchase one for the nice gentleman who sent it in for free, but I can't find it  ;)
 

Offline Bored@Work

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Re: EEVblog #680 - Mailbag
« Reply #19 on: November 04, 2014, 10:41:55 pm »
Cheap, easy, flexible, universal SMD PCB holder, holds the PCB as flat on the bench as it gets: eBay auction: #400751102673 (example only, no need to buy from eBay). Stick the PCB to the bench, solder as you please.
I delete PMs unread. If you have something to say, say it in public.
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Offline elgonzo

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Re: EEVblog #680 - Mailbag
« Reply #20 on: November 04, 2014, 11:20:34 pm »
Hi
Thanks for the PCB holder review
There are groves top and bottom to keep the board from droping down.
Made some up there for sale on
https://www.tindie.com/products/Z2instro/pcb-assembly-holder/?pt=directsearch

Regards
Leo

Much appreciated that you put your tool up for sale for anyone interested. However, the Tindi price frankly is not very favorable.

Flat drill vices with similar 4-inch clamping width can be bought almost anywhere (i guess) for similar or less that price (like this one with rubberized jaws ). Aside from being more robust, the clamping area of those vices is not obstructed by the worm drive. I am not saying that your little tool is not useful. But for the given (Tindi) price i would rather purchase a drill vice, which is equally suited as a (heavy-weight) PCB holder.

If you already have a drill vice with flat metal clamps, just get some cheap magnetic rubber or nylon jaws (like this one) and you got yourself a PCB holder...

(Btw, I actually use sometimes a drill vice similar to this one as PCB holder. However, this model only has a clamping width of 80 mm / 3 inch.)
« Last Edit: November 05, 2014, 12:26:08 am by elgonzo »
 

Offline Macbeth

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Re: EEVblog #680 - Mailbag
« Reply #21 on: November 04, 2014, 11:34:29 pm »
Dave, did my old eyes just see an 8-inch floppy disk on your shelf there?
Also, i spotted a few males. I think they're winners...  ;D  or not...  >:D
I'm amazed that an early '70s PDP/8 was less than $600. I remember picking one up back in the late '80s donated by an old engineer complete with 640k hard drive and 16k core memory, two mag tape drives, 4 terminals, and a paper tape reader for our school computer lab. The Elfen Safety narks wouldn't allow it to be switched on and so it was sold for the scrap metal and gold pcb value. The wire wrapping those girls did back in the day was utterly amazing. When we did switch it on before HSE jobsworths got involved it had no ROM, so we had to type in a bootloader on the front panel in 12-bit octal, that would fire up the paper tape reader to load in the boot code to fire up the mag tape drives and the HDD that was the size of a washing machine. Eventually the TTY terminals would flicker to life with DEC OS/8. Amazing to see compared to the BBC Micros and ZX Spectrums we had at the time.

Now somebody is going to tell me you could buy a house for $600 back then. Fecking inflation!  :-DD
« Last Edit: November 05, 2014, 12:30:16 am by Macbeth »
 

Offline Stephen Durr

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Re: EEVblog #680 - Mailbag
« Reply #22 on: November 04, 2014, 11:52:17 pm »
 :-+ Thumbs up for the Wayback Wednesday idea.  One of my favorite videos was the one where you went through your old magazines.  I really like seeing the old articles and advertisements and listening to your commentary on them.  Please do more!
"These go to eleven", Nigel Tufnel
 

Offline richfiles

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Re: EEVblog #680 - Mailbag
« Reply #23 on: November 05, 2014, 05:03:56 am »
Gotta love those old mags! I saw things i own in that magazine! I happen to have two Monroe calculators, a 1920 and a 1930, like the one shown in the ad at 42:10 in the video.

The 1920 is broken, but my 1930 works flawlessly. Functionality was quite unusual... You selected the function you wanted to use with a switch. There were two banks of functions, so you could have two functions selected at a time, and then you had an action key for each switch to execute the function selected by the switch. This allowed them to have far more functions than actual keys.

I personally love the idea of a Wayback Wednesday! I LOVE retro gadgets. I've got calculators front the mid 1960s, and even parts from a thyratron TUBE calculator! Oh yeah, the drive for that 8 inch floppy is sitting next to the SCM Cogito 240SR on my bottom shelf of the second pic! :D
« Last Edit: November 05, 2014, 07:42:01 am by richfiles »
 

Offline thismuchvolume

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Re: EEVblog #680 - Mailbag
« Reply #24 on: November 05, 2014, 05:56:59 am »
I was pretty excited to see him whip out that box with the Caterpillar power edge logo on it. An EMS display! I work for Caterpillar as an engineer and have been wanting to send something in to the EEVBlog for a long time but I never could decide what.

Now, a little info:
Those things you were pressing as if they were switches are actually just a partially opaque insert over LEDs. Those are used for indication of things like a charging problem, seat belt not buckled, check engine light, or any other indication we might want to show the operator. These displays are commonly used across all different machines, and the insert is changed depending on what makes sense for any given machine to show. That way they only have to manufacture a single display and use it all over the place. Caterpillar is big on part reuse. This display is intended to be partnered with a few other modular display pieces that show tachometer, ground speed, odometer, and other useful data. They are all in the same form factor and can link up through a communication bus to each other. I've attached a unfortunately small picture of several of the displays working together. You can see near the top right of the picture is the particular display that Dave as given.

As for doing a teardown on this thing, I'll ask one of our ECM Hardware guys if there is a trick to getting that screen off. Since our ECMs are really well sealed against environmental ingress, they are also a pain in the butt to open up and work on. Usually the method involves a sharp chisel and a large hammer, then a series of flathead screwdrivers/prybars.

If anyone has any questions about it or anything related I'd be happy to try to answer what I can.

Also, this finally spurred me to register here rather than just lurk! First post, woo.
 


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