EEVblog #872 - Mailbag - Page 1
Forum section: electronics / general

author: ElektronikLabor
author_rank: Regular Contributor
timestamp: April 26, 2016, 08:05:32 am
content: SPOILERS:Zifnu Rocket Kit:http://zifnu.com/Kickstarter:https://www.kickstarter.com/projects/...PAX Instrument T400 Temperature Loggerhttp://paxinstruments.com/t400-temper...Arris Cable Modem teardownMail from Claire StandishSinclair ZX81 Computer Teardown3D Printed glow in the dark DeloreanGarmin Fishfinder Teardownhttp://antdiy.blogspot.com.auCheap Ebay $9 multimeter teardownSharp EL-5810 pocket scientific calculatorDave's uCalc project.

author: ElektronikLabor
author_rank: Regular Contributor
timestamp: April 26, 2016, 08:09:09 am
content: Bigclive has already done a review of that water heater:https://youtu.be/EViyccc2t9wIs it even legal?You can kill somebody with that heater!

author: RobertoLG
author_rank: Frequent Contributor
timestamp: April 26, 2016, 08:11:12 am
content: Big clive did a video on these heater death trapshttps://youtu.be/hIUJWIT9GrU

author: crispy_tofu
author_rank: Super Contributor
timestamp: April 26, 2016, 08:19:10 am
content: 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

author: charlespax
author_rank: Regular Contributor
timestamp: April 26, 2016, 09:40:39 am
content: 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 youIf you're interested in rounding out your toolbox with a temperature datalogger, the T400 is available inmy storeand onAdafruit.All source files can be found on github. This includes the enclosure and even the customSMD thermocouple connectors. I love having the connector stamping tool under my work benchGithub electronics repositoryGithub firmware repositoryGithub enclosure repositoryIf you'd like to share your feedback for the T400 or ideas for future projects, please come join thePax Instruments forum.Jump directly to the T400 review: youtube.com/watch?v=UvJD8hbFbhU&t=30m45s

author: firewalker
author_rank: Super Contributor
timestamp: April 26, 2016, 10:00:56 am
content: 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.binCode:AUTOCONTRASTDEFAULTSDEPTH@ALARMFATHOMSFEETFISH@ALARMFISH@IDFIXEDGAIN?MORE?>MORE>METERSNOISE@REJECTNRMLRANGESETUPSHALLOWSIMULATORUNITSVIEWWHITELINEZOOMAlexander.

author: EEVblog
author_rank: Unknown
timestamp: April 26, 2016, 10:38:26 am
content: Quote from: medvedev on April 26, 2016, 08:09:09 amOh well, mine's already shot and uploaded.

author: LapTop006
author_rank: Unknown
timestamp: April 26, 2016, 11:26:09 am
content: Quote from: charlespax on April 26, 2016, 09:40:39 amI think the site needs an update."Currently being manufactured. Expected to ship in January 2016."

author: Razor512
author_rank: Regular Contributor
timestamp: April 26, 2016, 11:37:05 am
content: 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:TaYAAOSw9r1WDGQxAs 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.

author: EEVblog
author_rank: Unknown
timestamp: April 26, 2016, 11:39:28 am
content: Quote from: Razor512 on April 26, 2016, 11:37:05 amHOLY CRAP!

author: Wytnucls
author_rank: Super Contributor
timestamp: April 26, 2016, 12:02:33 pm
content: Vaguely related:

author: Brumby
author_rank: Unknown
timestamp: April 26, 2016, 01:57:26 pm
content: Quote from: EEVblog on April 26, 2016, 11:39:28 amAs 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:)"

author: charlespax
author_rank: Regular Contributor
timestamp: April 26, 2016, 02:53:50 pm
content: Quote from: LapTop006 on April 26, 2016, 11:26:09 amFixed. Thank you.

author: MatthewMorgan
author_rank: Regular Contributor
timestamp: April 26, 2016, 03:41:25 pm
content: 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).

author: erichill
author_rank: Newbie
timestamp: April 26, 2016, 06:10:01 pm
content: Quote from: medvedev on April 26, 2016, 08:05:32 amThat'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.

author: ChunkyPastaSauce
author_rank: Unknown
timestamp: April 26, 2016, 09:38:18 pm
content: 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).

author: rrinker
author_rank: Super Contributor
timestamp: April 26, 2016, 10:45:54 pm
content: 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.

author: smithnerd
author_rank: Regular Contributor
timestamp: April 27, 2016, 01:25:35 am
content: Quote from: rrinker on April 26, 2016, 10:45:54 pmI 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.

author: rrinker
author_rank: Super Contributor
timestamp: April 27, 2016, 01:39:35 am
content: 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

author: smithnerd
author_rank: Regular Contributor
timestamp: April 27, 2016, 02:16:51 am
content: Photo

author: smithnerd
author_rank: Regular Contributor
timestamp: April 27, 2016, 02:34:18 am
content: 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.

author: bryanrj1
author_rank: Contributor
timestamp: April 27, 2016, 04:52:07 am
content: 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.

author: Fungus
author_rank: Super Contributor
timestamp: April 27, 2016, 08:48:23 am
content: Quote from: smithnerd on April 27, 2016, 01:25:35 amYep. 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).

author: Fungus
author_rank: Super Contributor
timestamp: April 27, 2016, 09:00:49 am
content: Quote from: smithnerd on April 27, 2016, 02:34:18 amMint 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/252358789467Those were the days - when you could save 20 pounds on a home computer by soldering it yourself.

author: stmdude
author_rank: Frequent Contributor
timestamp: April 27, 2016, 09:40:30 am
content: Quote from: Fungus on April 27, 2016, 09:00:49 amThat's how I got my first computer. Soldered a ZX81 when I was 8. Damned thing even worked.

author: Fungus
author_rank: Super Contributor
timestamp: April 27, 2016, 10:46:49 am
content: Quote from: stmdude on April 27, 2016, 09:40:30 amEight? Damn, that's young. I must remember that next time somebody tells me that their kid is too young for dangerous toys like soldering irons.

author: rrinker
author_rank: Super Contributor
timestamp: April 27, 2016, 12:19:21 pm
content: What's crazy is that only a few years before you could buy the fully assembled TS-1000 for $99, I had built my first computer, which cost $106 plus extra for the address displays, and it didn't have a full keyboard, only a hex keypad, and LED displays. It had video output, but with the mere 256 BYTES of memory, the best you could do was 64x32 resolution, and part of what showed on the screen included a graphical representation of the code generating the picture. For ANOTHER $100 the following year I added the expansion board which gave it a whopping 4K of memory (still no BASIC or anything more than a monitor routine). Now you could do 64x128 graphics and not have to display the program. Approximately 2 years later, the TS-1000 appeared at the $99 price point. Leading up to that, I seem to recall the ZX-81 being offered at around $130, or $99 for the kit.Some of the other accessories I remember are both external 'proper' keyboards and one product that clipped over the case and gave moving keys that simply pressed down the existing membrane switches when struck. There may have been an intermediate product, or maybe it was just one of the full keyboards, that required you to open up the computer and pull off the flex cable from the stock keyboard and plug in its cable in place.

author: Fungus
author_rank: Super Contributor
timestamp: April 27, 2016, 12:44:01 pm
content: Quote from: rrinker on April 27, 2016, 12:19:21 pmThe ZX81 was popular because:a) It was cheapb) It connected directly to a TV and had a cassette portc) You could copy cassettes easily - free games! (unlike Ataris and TIs which used uncopyable cartridges*).Most "computer clubs" of that era were just groups of people with a bunch of cassette recorders connected together for copying stuff.(*) Yes, I'm sure some of you guyswouldhave been able to copy cartridges but most people couldn't.

author: stmdude
author_rank: Frequent Contributor
timestamp: April 27, 2016, 02:41:02 pm
content: Quote from: Fungus on April 27, 2016, 10:46:49 amThere were different standards back then. I still have some scars from learning how to solder.I don't think a "modern" parent would accept that.Quote from: Fungus on April 27, 2016, 12:44:01 pmYou missed one. The manuals for the Sinclair computers were _really_ good (for its time). I learnt BASIC from just the literature included with the ZX81.

author: Fungus
author_rank: Super Contributor
timestamp: April 27, 2016, 02:58:34 pm
content: Quote from: stmdude on April 27, 2016, 02:41:02 pmYep. I forgot that one.http://zxnext.narod.ru/manuals/ZX81_Manual.pdfStephen Vickers was a top manual writer.

author: robin7g
author_rank: Newbie
timestamp: April 29, 2016, 01:01:42 am
content: Quote from: smithnerd on April 27, 2016, 01:25:35 amRE: Memotech RAM pack.It did!! Sharp eyes. I took the Memotech RAM pack off before I sent it. Sorry Dave.

author: robin7g
author_rank: Newbie
timestamp: April 29, 2016, 01:18:47 am
content: This is the original Sinclair RAM pack with the wobbling problem. The ZX81 under it started life as a kit. The circuit board tracks are all wavy hand routed ones which is the issue 1 layout.

author: rrinker
author_rank: Super Contributor
timestamp: April 29, 2016, 01:24:48 am
content: Found what I was looking for. I remember buying this magazine. I just read the one on the top left, VOl 3 #5, and remember that issue specifically. Check the ads for add-ons. All SORTS of stuff. And there are at least 2 adds for the stick on top keyboard I mentioned, plus others that were full external keyboards.https://archive.org/details/syncmagazineMemotech was one that had a full line of accessories, not just memory expansion. This issue also has a small item on doing the direct composite output - same circuit that was included in the package sent to Dave.

author: Fungus
author_rank: Super Contributor
timestamp: April 29, 2016, 09:28:45 am
content: Quote from: robin7g on April 29, 2016, 01:18:47 amThe 'problem' is that it's a crap connector with an unsupported, unbalanced plastic box connected to it. Any type of vibration will wobble the connector, including normal typing on the keyboard.Magazines at the time were always full of fixes for RAM pack wobble - rub your PCB contacts with hard pencil erasers, put blu-tack between the RAM pack and computer, use strips of velcro, build up the PCB contacts with solder to get a tighter fit, etc. None of them really worked. Sudden memory loss was a fact of life.

author: smithnerd
author_rank: Regular Contributor
timestamp: April 29, 2016, 01:52:13 pm
content: What's striking about the Memotech RAM pack is how well made (and designed) it is.It's obviously a custom aluminium extrusion, which can't have been cheap to make. The fit and finish is superb.

author: Arlen Moulton2
author_rank: Regular Contributor
timestamp: April 29, 2016, 03:37:25 pm
content: hey dave, how much would it cost for you to send one of the sinclairs to the uk?

author: blackbird
author_rank: Regular Contributor
timestamp: April 29, 2016, 06:24:20 pm
content: Ah the ZX81, brings back good memories, one of the first computers I've used when I was 7 years old. The next year I got the ZX Spectrum as my birthday present (age eight). At school they could not believe my parents gave me a 'real' computer.They had only one computer at the administration department.

author: Fungus
author_rank: Super Contributor
timestamp: April 29, 2016, 07:19:20 pm
content: Quote from: Arlen Moulton2 on April 29, 2016, 03:37:25 pmProbably more than just buying one in the UK:http://www.ebay.co.uk/sch/i.html?_nkw=zx81

author: robin7g
author_rank: Newbie
timestamp: April 30, 2016, 01:39:05 am
content: Quote from: smithnerd on April 29, 2016, 01:52:13 pmI remember as a kid getting the 16K Memotech RAM Pack because it was cheaper than the official Sinclair one. I think I was 8 years old. The Memotech was and is better than the official Sinclair RAM pack. Just better in all respects. But knowing what I know today I wish you could have just got 32K Static RAM and solder it in. All of that faffing about with ram packs.http://www.zx81.de/english/32k-rame.htmI think the ZX81 was a lot about programming and hacking them and adding their own stuff. I remember typing in programs for magazines and a kid in my neighbourhood build a full size keyboard and wooden case.

author: Fungus
author_rank: Super Contributor
timestamp: April 30, 2016, 01:00:15 pm
content: Quote from: robin7g on April 30, 2016, 01:39:05 amNot least because it was longer and you had more options to fix it firmly to the back of the computer.Quote from: robin7g on April 30, 2016, 01:39:05 amThe connector they used was one of the worst possible choices.But ... it was also the cheapest. It literally adds zero cost to the base hardware - just traces on the PCB and a hole in the back of the case..Maybe they could have added a couple of self-tapping screws to screw it onto the back of the machine or something. I dunno.

author: Arlen Moulton2
author_rank: Regular Contributor
timestamp: April 30, 2016, 03:03:58 pm
content: Quote from: Fungus on April 29, 2016, 07:19:20 pmdave sent me the motherboard out of that tablet for free and that is the same size as the zx81.

author: Fungus
author_rank: Super Contributor
timestamp: April 30, 2016, 07:24:13 pm
content: Quote from: Arlen Moulton2 on April 30, 2016, 03:03:58 pmPostage was free?

author: Brumby
author_rank: Unknown
timestamp: May 01, 2016, 02:22:55 am
content: Quote from: Fungus on April 30, 2016, 07:24:13 pmHow to start an argument on eBay....

author: Arlen Moulton2
author_rank: Regular Contributor
timestamp: May 02, 2016, 08:04:10 pm
content: Quote from: Fungus on April 30, 2016, 07:24:13 pmthen the postage will be free on this!