EEVblog #827 - Mailbag

[EEVblog]

More Mailbag Monday.



SPOILERS:
RemoteBoot Kickstarter: https://www.kickstarter.com/projects/658903329/remoteboot-wifi-remote-management-module-for-pcs

Digilent PowerBric: https://www.kickstarter.com/projects/658903329/remoteboot-wifi-remote-management-module-for-pcs
Arty Artix-7 FPGA Development Board
http://www.digilentinc.com/Products/Detail.cfm?NavPath=2,400,1487&Prod=ARTY&CFID=21499368

[max666]

Dave you goofed up the "Digilent PowerBric:"-link, here and on YT.

That Elektrosluch 3 thing was more fun than I expected. But € 90.00 is a little steep, if you ask me, for something that simple. Have to build that up my self for fun.

[Dave Turner]

Hi Dave

What's your beef with the white silk screen?  For my sight it is one of the clearest silk screens I've seen. I could easily read everything. Surely clarity is a good thing.

Regards

Dave

[CrashO]

What's your beef with the white silk screen soldermask?  For my sight it is one of the clearest silk screens I've seen. I could easily read everything. Surely clarity is a good thing.

Probably the same reason I hate them (and black mask) too.
It's hard to see the traces.. Seeing easily where traces are going is more valuable to me than crispy clean silkscreen.

[mikeselectricstuff]

The remote PC reset thing is a neat idea, but That wifi module isn't going to work well with that solid groundplane behind it.

Could also have saved themselves some fiddly soldering by combining the pin headers into a larger one.

[v8dave]

It's a WHITE soldermask with BLACK silkscreen not white silkscreen

For final boards it's fine but for prototyping I prefer the standard green as you can still see the tracks.

[hcglitte]

Anyone noticed the ground plane beneath the WiFi module...? If you are reading this Ben, you should remove the ground plane below the antenna and also at some distance to it from the sides.

[janoc]

Dave, that "record player" is actually guts from an old talking doll. My sister had one exactly like that when we were kids - you pushed a button on the back and it said something, depending on the record that was in. You could even get different records for it with songs and what not.

[v8dave]

Anyone noticed the ground plane beneath the WiFi module...? If you are reading this Ben, you should remove the ground plane below the antenna and also at some distance to it from the sides.

I saw that too. The range will be reduced quite a bit if he doesn't remove this around the antenna area.

[AF6LJ]

Good Stuff from one of the 2%

[AF6LJ]

Dave, that "record player" is actually guts from an old talking doll. My sister had one exactly like that when we were kids - you pushed a button on the back and it said something, depending on the record that was in. You could even get different records for it with songs and what not.

They use to sell those here as a Bag of Laughs.

[Dave Turner]

Ok I see your point regarding the 'hidden' tracks whilst developing a 2 layer prototype.

However, for a multilayer board the comment is less relevant as much is hidden internally. Also it strikes me as sour grapes 'cos' it makes it harder to reverse engineer visually.

 

[Someone]

The EM sniffer is picking up the change in frequency/duty cycle of the camera power supply as its dumping data to the drive/flash, there are big power demands for data writes.

[kindiana]

Designer of Remoteboot here, the ground plane now has a cutout under the antenna, thank you all for the feedback.

[tpw_rules]

The Elektrosluch has been known to the telephone industry for a while. The telephone-ish thing is their equivalent. The real tool is the other box, which generates a warbling tone to put on ethernet, telephone wire, etc. This turns the wire into a giant antenna and following the warbling with the pointy phone as the wire snakes in walls and through pipes is super easy. I have a set from my uncle in the trade and it was invaluable trying to label breakers in our ancient house.

[SteveLy]

The minidisc was one of the best portable recorders in its day. Kind of a Zoom H2n of the late 1990s, early 2000s. I've recorded a few gigs with one and it did a great job when it worked. Sound quality was amazing for a small device (even just with the small external stereo mic that came with it). But the discs (and/or the read/write mechanism) became unreliable after a while and you'd end up with unreadable chunks of data on your recordings, which was most disappointing.

That Slovakian RF snoop box is cool.

[con-f-use]

The maximum output capacity thing could be, because the USB standard only allows 10uF of capacity. I suspect it's an inrush and fuse thing.

[boffin]

The Bzz Bzz Bzz, isn't the line to the LED, it's the bulk data-write to the SD Card.

[aveekbh]

The Bzz Bzz Bzz, isn't the line to the LED, it's the bulk data-write to the SD Card.

The SD clock will be 50 to 100-odd MHz, so it's quite likely that that's what we're hearing. The LED current draw wouldn't likely emit so loudly (pun intended).

[station240]

The remote PC reset thing is a neat idea, but That wifi module isn't going to work well with that solid groundplane behind it.

Could also have saved themselves some fiddly soldering by combining the pin headers into a larger one.

If you've seen inside a PC, you'd know the for the wires for the various buttons/leds are on individual 2-3 pin headers. So a single large header is in fact harder to connect into, as you can't get easy grip on the plugs. Also less prone to install mistakes, as you can rewire the various buttons one at a time.

My own PC motherboard came with a piggyback header, which you plug all the loose 2-3 pin plugs into, then plug the single large one into the motherboard.


I too liked the Elektrosluch 3, though I'm more interested in seeing if it could be used to make a proper EMF compliance tool. I'll have a dig through my inductor pile to see if I have any suitable ones.

[SeanB]

Just look for any ferrite inductors with open magnetic systems, and anything from around 1mH upwards will work, current capacity not too important. If you can only get PC power supply ones try them, and if no joy simply rewind the core with as many turns of 30 SWG or thinner wire as it can hold.

The buzzing on the camera is likely from the data blocks being written to the card, the amplifier demodulating the envelope of the write blocks, demodulating the RF signal.

[ConKbot]

Just look for any ferrite inductors with open magnetic systems, and anything from around 1mH upwards will work, current capacity not too important. If you can only get PC power supply ones try them, and if no joy simply rewind the core with as many turns of 30 SWG or thinner wire as it can hold.

The buzzing on the camera is likely from the data blocks being written to the card, the amplifier demodulating the envelope of the write blocks, demodulating the RF signal.

The amplifier used is a FET input one(more immune to RFI compared to a bipolar input) and it looks like it is being run as a low pass filter. If you really wanted to catch higher frequency RF stuff, throw a RF schottky diode(1N5711 maybe? from a very very brief digikey search) on the input as an envelope detector, and you should be able to pick up even more stuff. With the stereo jack sticking out of the front, and a connector with enough space in the housing, you could perhaps make a plug in module to extend the AM demod range of it.

[PinheadBE]

Dave, that "bag of laughs", you HAVE to make it work!

Why? Because, when you have, you can then turn the small recorded disc on its other side (just like eldery people used to do with their vinyl records, eons ago), and listen what's on thatside.

Just get Sagan out of the room first, because it's a bit more.... "adult oriented".... 

[Fungus]

Dave, that "bag of laughs", you HAVE to make it work!

I had one of those bags when I was a kid. 

Why? Because, when you have, you can then turn the small recorded disc on its other side  and listen what's on thatside.

Just get Sagan out of the room first, because it's a bit more.... "adult oriented".... 

Urban legend? Not gonna happen - the disk only has one side (just look at the disc in the video).

[fubar.gr]

That minidisc player is one of the late NetMD models released from 2001 onwards.

You could connect it via USB and essentially drag and drop MP3 files into it. In reality it was a bit more complicated than that, the included software would convert the MP3 to ATRAC and then transfer it to the disc, but the whole process was very fast.

You could fit 4 CD's worth of play time into a single minidisc at good sound quality, or the equivalent of 8 CDs at OK quality. And minidiscs were tiny, you could fit several in your pocket. Also, would last forever with a single AA battery, more than some modern mp3 players on their internal Li ion battery.

All in all, it was one of the best portable music players of the time. There were solid state storage solutions back then, but they were either ridiculously expensive, or they couldn't hold more than a hundred of megabytes worth of music, or they sucked in other areas, such as interface, build quality, battery time, etc.