Author Topic: EEVblog #813 - Mailbag  (Read 16425 times)

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Offline EEVblog

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EEVblog #813 - Mailbag
« on: November 03, 2015, 04:58:50 am »
Bumber Mailbag.
Guest appearance by Sagan



SPOILERS:
Sinclair / Thandar SC110 10MHz portable analog CRT oscilloscope form the 1980's!
Makerbeam by Chartup: https://www.chartup.com/index.php?cPath=1_2
A mystery device from a Police auction from Rossin Corporation
10MHz TCXO reference clock generator: http://www.bloguetronica.com/2015/08/gerador-de-relogio-gr10m.html
AST3TQ TCXO datasheet: http://www.abracon.com/Oscillators/AST3TQ.pdf
CC2541 Bluetooth microcontroller datasheet: http://www.ti.com/lit/ds/symlink/cc2541.pdf
Fitbit ripoff teardown
MMA955L Motion sensing pedometer datasheet: http://www.freescale.com/products/sensors/intelligent-sensors-and-sensor-hubs/motion-sensing-pedometer-platform:MMA9555L
Harbour Freight Cen-Tech multimeter teardown!

 

Offline crispy_tofu

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Re: EEVblog #813 - Mailbag
« Reply #1 on: November 03, 2015, 06:07:40 am »
Those Thandar/Sinclair SC110s (also called Thurlby SC110) show up on eBay once in a while for about US $50, some of them are even RS branded!  :-+
http://www.ebay.com/itm/Vintage-RS-SC110A-Thandar-Portable-Oscilloscope-/221840075629
Manual: http://www.kevinchant.com/uploads/7/1/0/8/7108231/thurlby_sc110-instruction-manual.pdf

And that cheapo multimeter is really similar to the DT-830, there are a lot of rebrands (there's a lot of them, some don't have transistor tester, backlight, etc.). They use the ICL7106 IC in these meters  ;) There's one at Jaycar (Digitech, $10) and one at Dick Smith (Digitor, in a shiny silvery plastic for $22).
There's even one that's UL listed, in case someone wasn't sure about the quality  :-DD
(Interestingly, it has CAT I on the front, unlike the Harbour Freight meter)
« Last Edit: November 03, 2015, 06:37:54 am by crispy_tofu »
 

Offline tec5c

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Re: EEVblog #813 - Mailbag
« Reply #2 on: November 03, 2015, 06:15:54 am »
Is it just me or does Sagan sound a tad British?
 

Offline EEVblog

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Re: EEVblog #813 - Mailbag
« Reply #3 on: November 03, 2015, 06:55:09 am »
There's even one that's UL listed, in case someone wasn't sure about the quality  :-DD

Just like the Batteriser is UL tested!  :-DD
 

Offline Dr Bob

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Re: EEVblog #813 - Mailbag
« Reply #4 on: November 03, 2015, 07:59:20 am »
The mystery sensor looks a bit like this patent from the same time frame:

http://www.google.com/patents/US4468658

dB
 

Offline Dr Bob

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Re: EEVblog #813 - Mailbag
« Reply #5 on: November 03, 2015, 08:03:42 am »
The first thing to do with those Harbor Fright meters is to delete the included battery before it leaks all over the place. I have a few of these meters that I've received for free at HF. They are handy to toss in a glove box or tool kit to have about for a bit of quick troubleshooting.

dB
 

Offline jwm_

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Re: EEVblog #813 - Mailbag
« Reply #6 on: November 03, 2015, 08:15:05 am »
The first thing to do with those Harbor Fright meters is to delete the included battery before it leaks all over the place. I have a few of these meters that I've received for free at HF. They are handy to toss in a glove box or tool kit to have about for a bit of quick troubleshooting.

dB

The battery isn't even alkaline, it is heavy duty meaning carbon-zinc construction. At least you can pull out some nice inanimate carbon rods from the batteries. They can save the day in a pinch.

Offline mrkva

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Re: EEVblog #813 - Mailbag
« Reply #7 on: November 03, 2015, 08:30:04 am »
Dave, I've sent you an item in August from Slovakia - did it arrive? Cardboard box, around 15x15x5 cm I have a tracking number, but all I get is that it left Slovakia.
 

Offline vk3yedotcom

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Re: EEVblog #813 - Mailbag
« Reply #8 on: November 03, 2015, 08:32:36 am »
My very wild guess for that sensor thing is a window microphone that could activate a tape recorder when someone talks. 

Or maybe it could be pointed at a mirror and detect any small movement due to talking?

Colin Mitchell might know ;)
If you're into amateur radio you might enjoy my books. Choice of 6. Electronic or paperback. Details here: http://home.alphalink.com.au/~parkerp/vk3yebooks.htm
 

Offline SteveLy

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Re: EEVblog #813 - Mailbag
« Reply #9 on: November 03, 2015, 10:06:44 am »
Child labour - done right.
 

Offline EEVblog

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Re: EEVblog #813 - Mailbag
« Reply #10 on: November 03, 2015, 11:06:58 am »
Is it just me or does Sagan sound a tad British?

Probably Pepper Pig & Mr Maker!
 

Offline Deathwish

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Re: EEVblog #813 - Mailbag
« Reply #11 on: November 03, 2015, 12:00:13 pm »
The mystery sensor looks a bit like this patent from the same time frame:

http://www.google.com/patents/US4468658

dB

Differential pyrolectic sensor ?
Electrons are typically male, always looking for any hole to get into.
trying to strangle someone who talks out of their rectal cavity will fail, they can still breath.
God hates North Wales, he has put my home address on the blacklist of all couriers with instructions to divert all parcels.
 

Offline Deathwish

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Re: EEVblog #813 - Mailbag
« Reply #12 on: November 03, 2015, 12:05:19 pm »
Having watched Sagan take the nut driver from dad's hands and listened to him articulate himself I can only say this to him.

Dont worry mate, it wont be long before you can park dad in his wicker chair on wheels in the corner and watch him as he drools when you take over the show.  :-DD
Electrons are typically male, always looking for any hole to get into.
trying to strangle someone who talks out of their rectal cavity will fail, they can still breath.
God hates North Wales, he has put my home address on the blacklist of all couriers with instructions to divert all parcels.
 

Offline mikerj

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Re: EEVblog #813 - Mailbag
« Reply #13 on: November 03, 2015, 12:35:31 pm »
The first thing to do with those Harbor Fright meters is to delete the included battery before it leaks all over the place.

How do you delete a battery?  I never use cheapo included batteries in anything I actually care about keeping.
 

Offline WN1X

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Re: EEVblog #813 - Mailbag
« Reply #14 on: November 03, 2015, 01:32:59 pm »
(Interestingly, it has CAT I on the front, unlike the Harbour Freight meter)

I love how the Cen-Tech meter is marked as being Cat II rated  :-DD
- Jim
 

Offline Fungus

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Re: EEVblog #813 - Mailbag
« Reply #15 on: November 03, 2015, 02:49:15 pm »
Don't complain, your meter has a fuse in it!

When I did my teardown video there were no fuses at all in either of mine.

...and an on/off switch! Luxury!!


PS: Yes, they're pretty damn accurate, rugged, too!


I want to know why they bother with the transistor tester. It's totally useless and costs them money.  You'd think that would be the first thing to go when they look at the build cost. :-//
« Last Edit: November 03, 2015, 02:58:15 pm by Fungus »
 

Offline max666

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Re: EEVblog #813 - Mailbag
« Reply #16 on: November 03, 2015, 03:53:15 pm »
...
PS: Yes, they're pretty damn accurate, rugged, too!
...

Some bloke having a swim with his meter. Where have I seen this method for testing multimeters before? 
 

Offline djQUAN

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Re: EEVblog #813 - Mailbag
« Reply #17 on: November 03, 2015, 04:17:51 pm »
AFAIK Cen-Tech is the HF brand for their tools or something like that.

The multimeter PCB is not actually routed. It is cut (stamped?) with a cutter and die. Have a look at the PCB edges and they are kind of frayed, not the clean, smooth edge you get when they are milled.

It costs more to make the cutter but only a one time cost. Then cutting the PCBs is just stamping them out like cookie cutters.

The entire PCB outline is cut including the slots, large and odd shaped holes in just one step.

We did this where I used to work. The prototypes are done as we are all familiar with using milling and drills but once the PCB shape is finalized, the mass produced product will use the cookie cutter thing. I forgot what they call it in the industry.
 

Offline free_electron

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Professional Electron Wrangler.
Any comments, or points of view expressed, are my own and not endorsed , induced or compensated by my employer(s).
 

Offline Towger

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Re: EEVblog #813 - Mailbag
« Reply #19 on: November 03, 2015, 06:06:15 pm »
Those multimeters cannot be too dangerous.  My father managed to blow the tips off his probes, trying to measure the voltage across an immersion element...
He lived to tell the tail, but he still thinks there was something wrong with the meter, rather than 'user error'...
 

Offline woox2k

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Re: EEVblog #813 - Mailbag
« Reply #20 on: November 03, 2015, 07:18:56 pm »
You can't argue the fact that these free multimeters are great value for money. They still are reasonably accurate for everyday use. I agree that these shouldnt be used as a mains testers but for <50v everyday measurements they are fine.

About the safety, i own similar looking unbranded and even unfused meter. I once foolishly tried to measure a car battery when probes were in 10A plug... :palm: Needles to say i am still here to tell the story because apparently those "patented safety probe leads" acted as a fuse and the lead just broke in the middle instantly, i barely even saw the sparks coming off the battery terminals  :-DMM I still use that meter sometimes, with new cheap probes.
 

Offline Ampere

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Re: EEVblog #813 - Mailbag
« Reply #21 on: November 03, 2015, 07:47:18 pm »
I have a few of those Harbor Freight meters. I keep one in my trunk. I wouldn't use them to measure any amount of current, but they're still quite useful to keep around for voltage or resistance measurements.
 

Offline Christe4nM

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Re: EEVblog #813 - Mailbag
« Reply #22 on: November 03, 2015, 08:28:42 pm »
That intro with EEVblog junior mark 1 is a keeper!  :)  I instantly gave a tumbs up before watching the rest of it.

About that multimeter; how about a high voltage test? It's been too long since we saw something being blown up  >:D
 

Offline Don Hills

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Re: EEVblog #813 - Mailbag
« Reply #23 on: November 03, 2015, 09:43:56 pm »
The battery isn't even alkaline, it is heavy duty meaning carbon-zinc construction. At least you can pull out some nice inanimate carbon rods from the batteries. They can save the day in a pinch.

Have you seen any carbon-zinc 9v batteries with cylindrical cells inside? All the ones I've seen have a stack of "pancake" cells inside.
 

Offline wojteks

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Re: EEVblog #813 - Mailbag
« Reply #24 on: November 03, 2015, 11:07:24 pm »
On the topic of oldschool miniature CRO's - my recent eBay score:
https://www.eevblog.com/forum/testgear/oldschool-1972-polish-oscilloscope-ebay-score/
 


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