EEVblog #872 - Mailbag

[ElektronikLabor]

SPOILERS:
Zifnu Rocket Kit:
http://zifnu.com/
Kickstarter:
https://www.kickstarter.com/projects/...
PAX Instrument T400 Temperature Logger
http://paxinstruments.com/t400-temper...
Arris Cable Modem teardown
Mail from Claire Standish
Sinclair ZX81 Computer Teardown
3D Printed glow in the dark Delorean
Garmin Fishfinder Teardown
http://antdiy.blogspot.com.au
Cheap Ebay $9 multimeter teardown
Sharp EL-5810 pocket scientific calculator
Dave's uCalc project.

[ElektronikLabor]

Bigclive has already done a review of that water heater:
https://youtu.be/EViyccc2t9w

Is it even legal? You can kill somebody with that heater!

[RobertoLG]

Big clive did a video on these heater death traps

https://youtu.be/hIUJWIT9GrU

[crispy_tofu]

Uyigao, the manufacturer that produced the multimeter in the mailbag, also reuses the case for a lot of their other products:
- UA6013L capacitance tester (Deathwish on the forum bought this, I wonder what happened to him  )
- UA6243L LCR meter
- UA33 multimeter series

[charlespax]

I'm super excited to see the T400! I couldn't have done it without the direct help from a few friends and support from many others. Dave's vblog and this forum have also given me endless inspiration. I even put threaded inserts in the enclosure just for Dave. I would just like to say to everyone, thank you   

If you're interested in rounding out your toolbox with a temperature datalogger, the T400 is available in my store and on Adafruit.

All source files can be found on github. This includes the enclosure and even the custom SMD thermocouple connectors. I love having the connector stamping tool under my work bench 
Github electronics repository
Github firmware repository
Github enclosure repository

If you'd like to share your feedback for the T400 or ideas for future projects, please come join the Pax Instruments forum.

Jump directly to the T400 review: youtube.com/watch?v=UvJD8hbFbhU&t=30m45s

[firewalker]

Dave can you try reading the firmware of the Garmin FishFinder? I believe those models use an unlocked AVR. I had tested two of those some years ago. Running string on the binary:

strings fishfinder_80.bin

Code: [Select]

AUTO
CONTRAST
DEFAULTS
DEPTH@ALARM
FATHOMS
FEET
FISH@ALARM
FISH@ID
FIXED
GAIN
?MORE?
>MORE>
METERS
NOISE@REJECT
NRML
RANGE
SETUP
SHALLOW
SIMULATOR
UNITS
VIEW
WHITELINE
ZOOM


Alexander.

[EEVblog]

Bigclive has already done a review of that water heater:

Oh well, mine's already shot and uploaded.

[LapTop006]

...If you're interested in rounding out your toolbox with a temperature datalogger, the T400 is available in my store ...

I think the site needs an update.

"Currently being manufactured. Expected to ship in January 2016."

[Razor512]

Those are 100% safe, a little mains 240V won't hurt anyone, instead, it will just give you a little energy. For example, here is one labeled "AC 220v 2500w Bathtub Baby Swimming Pool Water Quick Heater Heating Tube"
http://www.ebay.com/itm/AC-220v-2500w-Bathtub-Baby-Swimming-Pool-Water-Quick-Heater-Heating-Tube-/331669347074?hash=item4d39089b02:g:TaYAAOSw9r1WDGQx

As we all know, babies sleep a lot, and that is because they do not get enough energy. But if we use a product like this while they are in the tub, or pool, then it does double duty, it not only keeps the water warm, but it can potentially keep the kit energized. This can make a bath or a swim much more refreshing.

With a larger pool of water, you can potentially have a device that will give you a quick recharge as you step in.

[EEVblog]

Those are 100% safe, you can use them a little mains 240V won't hurt anyone, instead, it will just give you a little energy. For example, here is one labeled "AC 220v 2500w Bathtub Baby Swimming Pool Water Quick Heater Heating Tube"
http://www.ebay.com/itm/AC-220v-2500w-Bathtub-Baby-Swimming-Pool-Water-Quick-Heater-Heating-Tube-/331669347074?hash=item4d39089b02:g:TaYAAOSw9r1WDGQx

HOLY CRAP! 

[Wytnucls]

Vaguely related:

[Brumby]

Those are 100% safe, you can use them a little mains 240V won't hurt anyone, instead, it will just give you a little energy. For example, here is one labeled "AC 220v 2500w Bathtub Baby Swimming Pool Water Quick Heater Heating Tube"
http://www.ebay.com/itm/AC-220v-2500w-Bathtub-Baby-Swimming-Pool-Water-Quick-Heater-Heating-Tube-/331669347074?hash=item4d39089b02:g:TaYAAOSw9r1WDGQx

HOLY CRAP! 

As if the product itself isn't cause enough for nightmares, they include this:
"We can also wholesale if you need a large quantity of item please contact us :)"

[charlespax]

...If you're interested in rounding out your toolbox with a temperature datalogger, the T400 is available in my store ...

I think the site needs an update.

"Currently being manufactured. Expected to ship in January 2016."

Fixed. Thank you. 

[MatthewMorgan]

So the little item i sent him did not arrive? (I know it arrived went to australia but ofcause australia post does not do international incoming tracking online).

[erichill]

Arris Cable Modem teardown

That's a DOCSIS cable modem commonly used in the US for internet access over the cable TV network.  The phone ports in the back allow the cable companies to provide telephone (POTS) service over the cable network to compete against the AT&T/Verizon/etc telcos.  The compartment on the bottom is for a battery pack because phones are required to work during a power outage in the event someone needs to dial emergency services.

[ChunkyPastaSauce]

The Arris modem module compartment is for a battery pack to support the telephone connections during a power outage (the internet part doesn't function).

[rrinker]

 Me three - haha I used to have that very cable modem, until I bought my own and stopped renting one from Comcast.

I had the Timex-Sinclair 1000 back in the day - they sold for $99.95 USD assembled. For the couple of years they were popular, there were some third party add-ons - Sinclair had a 16K memory backpack that plugged in that slot in the back (and were very prone to bad contact - move the computer just a little bit and it would lose contact and lock up the computer, wiping your program. There was a third party version that stretched the width of the back of the computer and had an angled shape to match, that company offered 16, 32, and 64K expansion modules, and if I remember correctly they could be stacked. There were some other interface options - I think Timex had a printer, and there were some other I/O piggyback modules. I wish I could find mine, since the house has been completely cleaned out and I haven't found it, it must be long gone. As you can see on the side it had cassette I/O for program saving, but what they didn't do is include a control for the cassette motor as found on other machines like the TRS-80. So what I did was build a little interface box that plugged in the side and gave me a power switch with LED, a reset button (wires soldered to the PCB inside), and a start/stop switch for the cassette motor - all just pass through connectors. I do wish I could find mine, it was a fun machine to mess with, there were a lot of tricks to get around some of the VERY severe limitations.
 A friend of mine, his father was a physics professor at a nearby college, he had CASES of them at one time, that interface on the back exposes all of the lines from the Z80, so anything that could connect to a Z80 - any of the peripheral interconnect chips, etc - could be attached and you could easily access all sorts of input and output.

 

[smithnerd]

...there were some third party add-ons - Sinclair had a 16K memory backpack that plugged in that slot in the back (and were very prone to bad contact - move the computer just a little bit and it would lose contact and lock up the computer, wiping your program. There was a third party version that stretched the width of the back of the computer and had an angled shape to match, that company offered 16, 32, and 64K expansion modules, and if I remember correctly they could be stacked...
 

I have a mint example right here - Memopak 16K by Memotech Ltd.

The velcro stuck on the back of Dave's one suggests it may have had one too.

I remember buying my first ZX81 in WHSmith's for 20 quid (heavily discounted) sometime in the mid 80s.

[rrinker]

 Yes, Memotech, that is one of the names I remember. I have to dig through some old magazines and see if I can find some of the others.
First hit I got looking had an ad for the ZX-81 kit version for $79.95USD.

And then there's this guy, who made some nice add ons, recently: http://www.rwapsoftware.co.uk/zx812.html

[smithnerd]

Photo

[smithnerd]

I found this ZX81 in a junk shop in 1995 for £3. My original was stolen in a burglary in the 80s, which was traumatic indeed.

[bryanrj1]

The Arris cable modem is also used where I work. There is approximately 200 thin clients connected to about 50 of these cable modems. The cable modems are connected to several broadband amps throughout the plant and eventually go back to a central Arris CMTS. The small battery in the bottom of the cable modem lasts about an hour during power outages. We don't use the phone jack at all.

[Fungus]

I have a mint example right here - Memopak 16K by Memotech Ltd.

The velcro stuck on the back of Dave's one suggests it may have had one too.

Yep. Dave didn't pick up the velcro. It was used to try and prevent the infamous "RAM pack Wobble" which would wipe your RAM out if you typed too hard.

The placement of the velcro definitely suggests a Memopack, not the official Sinclair RAM expansion (which was much narrower).

[Fungus]

I found this ZX81 in a junk shop in 1995 for £3. My original was stolen in a burglary in the 80s, which was traumatic indeed.

Mint condition!

I used to have a huge collection of home computers that I picked up when I worked as a games programmer in the 1980s.

I had some real rare stuff, even some prototypes/pre-production machines that were given to our company in the hope that we'd port a few games to them (fat chance!)

I gave a lot of them away and the rest have been lost in the mists of time (and several house moves). Oh, well... 

PS: There's a ZX81 kit up for sale on eBay: http://www.ebay.co.uk/itm/252358789467

Those were the days - when you could save 20 pounds on a home computer by soldering it yourself.

[stmdude]

Those were the days - when you could save 20 pounds on a home computer by soldering it yourself.

That's how I got my first computer. Soldered a ZX81 when I was 8.  Damned thing even worked.