EEVblog #553 - Mailbag

[EEVblog]

DIN 41612 Roth Electronics Extender Card: http://docs-asia.electrocomponents.com/webdocs/068f/0900766b8068f80e.pdf
Lichtenberg Figure: http://en.wikipedia.org/wiki/Lichtenberg_figure
http://focusdesigns.com/ Self Balancing Unicycle
Tektronix 213 oscilloscope: http://www.teknetelectronics.com/DataSheet/TEKTRONIX/TEKTR_21325410.pdf
http://www.testequipmentconnection.com/specs/Tektronix_213.PDF

[c4757p]

I'm probably just too much of a Tek fanboy, but damn, I want that cute little scope!

[dr.diesel]

Yeah, I have a raging erection, that Tek is awesome.

[ludzinc]

A good read on Litchenberg figures can be found here:

http://www.howtospotapsychopath.com/2007/12/03/lichtenbergia/

And some videos of them being made - also explains why the figure is captured in a layer.

[andtfoot]

Oooohh... do want one of those Lichtenberg thingies... 

Edit: Which Mike kindly pointed out in this thread that you can get from here.

[Bored@Work]

Dave, a quick google on the Tek 213 revealed those can have some battery pack inside that used to leak. Maybe a quick check on yours is in order to limit any potential damage.

[N2IXK]

According to the TekWiki, the 213 portable scope was first introduced in 1975.

http://w140.com/tekwiki/wiki/213

Not a lot of people had digital multimeters back then, so this scope must have been a real piece of geek porn in its day...

[Nilres]

Isn't it still geek porn? I love it!

[edpalmer42]

I used to work for a telco.  We had one of the Tek miniscopes in our testroom.  I think it was Model 214 - dual trace storage, 500 KHz bandwidth.  Very cute!

Here's some info on the family:  http://w140.com/tekwiki/wiki/Main_Page#200_Series

Ed

[Jon86]

That joke about the queen made me laugh more than I should have 

[joaoc]

This video shows how to do some pattern (in the end)

[dewhite2485]

This is Derek the one who sent you the scope, Im glad you liked it so much! When I got it on ebay the seller had it advertised as untested/non working, lucky for me when I got it everything worked like a charm. Some one has modified it slightly, the BNC connector on the back is not original to the design but seems to work. It didnt have the internal battery when I got it, but should be easy enough to replace if you wanted to use it cordless. Ive had the covers off it before so I know what it looks like inside, but it will be interesting to get a more technical look into its construction and operation.

[EEVblog]

This is Derek the one who sent you the scope

Thanks Derek, I think this teardown will be popular! 

[Chipguy]

Told ya, no text

[dr.diesel]

Thanks Derek, I think this teardown will be popular! 

Tomorrow is Tuesday     

[synapsis]

That scope is awesome! It's the numerical readout that made me want one. Nixie tubes are *so* last year. (Decade?)

[N2IXK]

Would really like Dave to tear into the character generator circuitry. I assume it is some kind of vector system, not raster scanned.  I agree that the CRT readout has it all over Nixies for sheer coolness. You can get CRT clocks as a kit nowadays:

http://oscilloclock.com/
http://www.cathodecorner.com/sc200c.html

For anyone who is curious about the guts of the Tek 213 and can't wait for Dave's teardown, check this out:

[Len]

Would really like Dave to tear into the character generator circuitry. I assume it is some kind of vector system, not raster scanned.

The char gen is a single chip with 4-bit binary input and x, y, z vector output.

Schematics for the Tektronix 213 are here: http://w140.com/tekwiki/wiki/213

[fpliuzzi]

Dave,
If you're interested in some info about that unusual CRT contained in the Sinclair portable flat TV, the "AndyDaviesByTheSea" channel on youtube has a video where the gentleman describes the part he played in the development of that CRT.

The video is "I little bit about my work and Sinclair's flat TV".  The Sinclair part starts at the 6:18 point.

Regards

[Zad]

Rick Dickinson, the fella who did the industrial design, has some photos of his work on the Sinclair TV on his Flickr page:



http://www.flickr.com/photos/9574086@N02/sets/72157601627816164/


I got a faulty one from a ham radio rally in the early 1990s and played around with it. The innards are pretty simple, with almost all the work done on one chip. The real interest is in the CRT design, as I'm sure people will see!

[rr100]

Yeah, I have a raging erection, that Tek is awesome.

If it was any longer I would've pissed myself. Awesome stuff!
1975 ... and true RMS to boot.
BRB, nature calls :-)

[amyk]

Would really like Dave to tear into the character generator circuitry. I assume it is some kind of vector system, not raster scanned.  I agree that the CRT readout has it all over Nixies for sheer coolness. You can get CRT clocks as a kit nowadays:

http://oscilloclock.com/
http://www.cathodecorner.com/sc200c.html

This reminded me of an article I read quite some time ago about using completely analog means to generate characters for a vector CRT, if I remember correctly it was a PDF scan of something from the 50s-60s era. Anyone know what I'm talking about?

[tjw]

Hi,
    GK mentioned this in his home brew analog computer thread, specifically :

 https://www.eevblog.com/forum/projects/home-brew-analog-computer-system/165/

GK links to http://www.nixiebunny.com/crtgen/crtgen.html about half way down page 12 of the thread.

Regards, TJW.

[84GKSIG]

that little scope is just beautiful! i need one just like it! now!

[Balaur]

I hope Dave got some footage of the Sinclair TV working before the Analogue signal was switched off. Damned close call if he did, or didn't.

IIRC, the TV wasn't working, as the main IC was missing (as described in the message accompanying the TV).

[Stonent]

Yeah, I have a raging erection, that Tek is awesome.

If it was any longer I would've pissed myself. Awesome stuff!
1975 ... and true RMS to boot.
BRB, nature calls :-)

If symptoms appear for more than 4 hours call your doctor.  I never understood those warnings. There's a lot less embarrassing ways to fix the problem than calling the doctor.

[Scott]

I've got four of the 200 series Tek scopes (214, 221 storage, and two 213 DMMs). I'll give away my secret: buy the ones on eBay that are not working at all. Usually the only thing wrong is the NiCd battery pack. If the battery pack is shot, the units often wont even run on AC power. Also, don't power the unit from AC power unless an battery pack is installed.

They are great little scopes. I was able to fit three scopes in my carry on luggage for Maker Faire last year!

[synapsis]

But now that Dave's had one on his channel, the price of the scopes will go through the roof!

[Stonent]

But now that Dave's had one on his channel, the price of the scopes will go through the roof!

Bonus if someone can figure out how to build a small scope board that connects to the back of a Sinclair TV!

[Zad]

You could probably run a (functional) Sinclair TV quite easily off the Raspberry Pi composite video output. Someone has to try that!

[amyk]

Hi,
    GK mentioned this in his home brew analog computer thread, specifically :

 https://www.eevblog.com/forum/projects/home-brew-analog-computer-system/165/

GK links to http://www.nixiebunny.com/crtgen/crtgen.html about half way down page 12 of the thread.

Regards, TJW.

That's the one!

I was able to easily find the PDF version after seeing that: http://www.thecorememory.com/GenCharforCRR.pdf

[Stonent]

You could probably run a (functional) Sinclair TV quite easily off the Raspberry Pi composite video output. Someone has to try that!

You'd need an RF Modulator to convert the Comp to RF signals.

[Zad]

It depends on what goes on inside the chip. It has a composite video output pin that you should be able to tap onto to inject the Rasp Pi's analogue output. It may be that the chip samples the signal before this point to derive synch etc.

[N2IXK]

There is a block diagram of the ZN401E-2 chip here:

http://www.thevalvepage.com/tv/sinclair/ftv1/announc.htm

Looks like the composite video could be injected right at the detector output, feeding both the CRT drive and the sync separator.

Does anyone have a copy of the actual Ferranti datasheet for the chip, or was this a proprietary design just for Sinclair? A really interesting design, using what appears to be a synchronous detector for the audio, and a PLL with dual DACs to produce the deflection waveforms.

[EEVblog]

There is a block diagram of the ZN401E-2 chip here:
http://www.thevalvepage.com/tv/sinclair/ftv1/announc.htm
Looks like the composite video could be injected right at the detector output, feeding both the CRT drive and the sync separator.

The chip is needed to generate all the timing though. Could be done manually, but messy.

[N2IXK]

Yes, without the magic chip, getting anything on the screen would be a LOT of work. Almost the entire signal processing system (video, audio, sync, and sweep generation) is contained in that little guy...

[JoannaK]

Sounds a lot like Fpga.project.. or Propeller.

[amyk]

I remember seeing online a schematic + datasheet for a Chinese-made portable CRT TV (recently) that had everything on one chip... but can't find it now.

Edit: found it!
http://shiximm.com/baogaofanwen/261729.html
http://datasheet.seekic.com/PdfFile/D29/D2915.pdf

[SeanB]

n the late 1980's Maplin was selling off the boards as spare parts, possibly working but without the CRT, main chip and tuner. Probably ones that were DOA from the assembly line, where they would pull the most expensive items ( Tuner, CRT and the ASIC) from them to reuse. Probably the main reason the ASIC was in a socket is that they were heat sensitive, and were the single highest cost item in the set, probably costing more than the CRT.

I watched the Andie Davies memories about Sinclair, was very entertaining on how difficult those were to make.

As to the battery packs, they were a part of instant film packs, used to drive the camera motors, focussing system and the flash circuitry. Pretty impressive for the first mass produced pouch cells, they were nice to use in projects as discards from camera packs, still having a lot of power left in them after the 120 shots from the film unit. Only issue was connecting to the aluminium foil tabs as they were not solderable. I generally used a crocodile clip or paper clip as a contact with a piece of magic tape as a cover for the clip.

[peter.mitchell]

I have that chip Dave if you want it. Don't know how long it would take to get there from the UK at this time of year but if you want to do a follow-up to that mailbag and get the thing working, I can stick it in the post for you.

Jon.

My experience with UK-> Aus any time of year is very quick. I'd say it would take a week, maybe 2, tops.

[beounet]

 
Hey Dave!! About the camera zoom issue, why don't you make a foot-pedal zoom switch?

[delmadord]

Just a quick GIF

[delmadord]

and just one more pic

[wilheldp]

As crazy/stupid as some people are with body modification, it would surprise me if a craze started where people were trying to get struck by lightning to get a "cool" Lichtenberg figure "tattoo."

[SeanB]

At least that would be self limiting, most do not survive the experience.

[IanJ]

As crazy/stupid as some people are with body modification, it would surprise me if a craze started where people were trying to get struck by lightning to get a "cool" Lichtenberg figure "tattoo."

If Doc Brown can do it (albeit unintentionally) then surely Dave will give it a go........



Ian.