EEVblog #624 - Mailbag

[EEVblog]

EEVblog2 2nd Youtube Channel:
https://www.youtube.com/channel/UCr-cm90DwFJC0W3f9jBs5jA

An Engineers Guide To Solving Problems Book:
http://amzn.to/1jNmoTz
https://www.youtube.com/user/trombonista92
A really crappy line tracer circuit patent
https://www.google.com/patents/US6222358
Geppetto Electronics LCDuino RGB backpack
http://www.geppettoelectronics.com/
TmpUSB temporary USB drive:
http://www.jmedved.com/tmpusb/
PIC Development Boards: http://www.gtronics.net/en/
https://www.youtube.com/user/BoomBrush
Sony Mavica 3.5" Floppy Drive Digital Camera
http://www.manualslib.com/manual/319933/Sony-Mavica-Mvc-Fd7.html
X-Core 16 Core 1000MIPS Analog Slice Kit:
https://www.xmos.com/products/xkits/slicekit

[Tronicgr]

Hi Dave!

You were wondering what real-time application would fit the x-core Analog SliceKit?
http://www.xmos.com/blog/20728/content/using-xcore-analog-slicekit-power-real-time-6dof-platform

BTW, I love the way you try to figure out how to connect things, without reading the manual first! The Mixed Signal Slice does not have a symbol as it not compatible with any other PCI connectors on the board! 

Cheers!

[Rasz]

Xmos - fantastic hardware.
 Its not really 16 cores, its two 500MHz CPUs with 8 virtual cores each. You might ask so what? well, its HOT. Eight 70MHz cores would consume less energy, but take more silicon space. Xcore claims 800mW for 8 core chip, but starter kit takes probably about 2 watts and gets really HOT.

pros:
We are talking bitbanging pins at >60MHz. Serializers/deserializers, complex GPIO clocking schemes, buffering. If a signal you want to play with is <100MHz you can use xcore instead of FPGA. C instead of verilog is very nice.

cons:
support doesnt exist. Looks like they have no staff manning the support forum, unanswered threads sit there for months. Documentation is an equal mess. They practically kept secret what chip is inside StartKit !?!? It takes a while to figure things on your own (or maybe their business model is milking for paid support).
dev tool (eclipse) requires online registration, you cant just download tools and install offline, feels like online drm
power consumption comparable to fpga



All in all think of it as an FPGA programmed in C. Want to process 10 i2S streams? no problem. Want to bitbang ethernet? sure! Interface your weird ass custom serial doohickie?  there you go. Plus they start really cheap at ~$3, cheaper than comparable FPGA (except Lattice).

[EEVblog]

All in all think of it as an FPGA programmed in C.

Except an FPGA doesn't have a 12 bit ADC in it, or a DC-DC converter, or program memory.

[EEVblog]

BTW, I love the way you try to figure out how to connect things, without reading the manual first! The Mixed Signal Slice does not have a symbol as it not compatible with any other PCI connectors on the board! 

Umm, yes, it does plug into the other connectors on the board! It should be marked with a matching A

[Alexei.Polkhanov]

That sidac-based circuit for line tracer is pretty interesting.

[Rasz]

Except an FPGA doesn't have a 12 bit ADC in it

not to worry, they charge ~$3 extra for the ADC, same as buying external one.

or a DC-DC converter

microsemi does
and you pay the price of fixed IO voltage

or program memory.

cmon,  blockram is ram

There is nothing xcore does that fpga couldnt feature wise, and Lattice has it beat in price. What xcore has going for it is programming language. You can have Python/php/javascript speaking web monkey producing actual running code on xcore in a day ( !!! ). Not gonna happen with FPGA.

[MadModder]

The twolegged "transistor" in that crappy blue detector is probably not a KT200E7 but a K1200E70 (the zero at next line) and that is a silicon bilateral voltage triggered switch. http://www.datasheetcatalog.com/datasheets_pdf/K/1/2/0/K1200E70.shtml
There are several different packages available, and TO92 is one of them.
The layout seems to have a space for either one.

[Tronicgr]

BTW, I love the way you try to figure out how to connect things, without reading the manual first! The Mixed Signal Slice does not have a symbol as it not compatible with any other PCI connectors on the board! 

Umm, yes, it does plug into the other connectors on the board! It should be marked with a matching A

Lol, true! But there are lots of "plugs" that fit to "wrong holes", that doesn't mean it will work.

http://www.teamanglingaddicts.com/2010/09/never-plug-in-wrong-hole.html   

[Alexei.Polkhanov]

The twolegged "transistor" in that crappy blue detector is probably not a KT200E7 but a K1200E70 (the zero at next line) and that is a silicon bilateral voltage triggered switch. http://www.datasheetcatalog.com/datasheets_pdf/K/1/2/0/K1200E70.shtml
There are several different packages available, and TO92 is one of them.
The layout seems to have a space for either one.

Up till yesterday I did not know what "sidac" is :-) I think it is interesting idea, but it will only work if wires are powered up and only at 120V (hence  matching sidac) and that makes it only half useful if at all. I have read that patent like 5 times. I hope I understand how it works, but could not find any sidacs in my parts box, only 2 diacs.

I wonder how does resulting waveform looks like on wire?

[SeanB]

Pretty similar, just a lot better current wise and slope wise. It step excites a RC oscillator and this is superimposed on the wiring as an oscillation with a 120Hz fundamental and a tone depending on the RC so you get a pulse train that disappears when the breaker is turned off. Simple and easy to detect above the usual line interference and noise.

[Laertes]

The weird german brochure is an educational brief about the elections for the European Parliament from the Bundeszentrale für Politische Bildung(Federal Centre for Political Education), which any citizen can just order(you can get brochures about any kind of political stuff, it's mostly meant for teachers and interested youths and stuff) and apparently get mailed to any kind of address around the world for no charge at all.
As to why in the world anyone would mail you something like that...well...   

[Towger]

Has anyone else noticed how Dave always flicks through books backwards?

That's a sign of intelligence, I do the same ;-)

[NiHaoMike]

I have a similar circuit breaker finder (Klein brand) that appears to have identical internals but actually works quite well. I suspect looser component tolerances or knockoff firmware that makes the knockoff not work as well. Also significant is that it has a rubber boot over the tip, which might be what's reducing the sensitivity to just the right level.

BTW, you can use the transmitter module and an AM radio to trace wiring.

[RupertGo]

One of the XMOS founders, David May, was the lead architect on the Inmos Transputer, a fascinating but failed UK processor design that was one of the first demonstrations that parallel computing isn't about the hardware after all... about the only aspect of it that was commercially successful was the fast serial interconnect, that Psion adopted in its later model Organisers for peripheral interfacing.

[SL4P]

... circuit breaker finder (Klein brand) that appears to have identical internals but actually works quite well..

The mailbag sender's issue may be that he should turn the breakers off - so there is less AC/RF conductance across to the shared mains phase/buss.
Then the individual circuit breaker ident tone may stand out a bit better.

[SeanB]

The way it works is it generates the tone always when powered, and you go to the breaker box and flip breakers off until you find out which one stops the tone. It does not show the line to the breaker, but that the other end still has power.

[jonwil]

I actually worked on that old Motorola during a 6 month student internship I did. Not the hardware but the software stack
Oh and the software stack on those things was even crappier to work on than it was to use FYI