EEVblog #847 - Mailbag - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: February 02, 2016, 08:55:32 pm
content: Mailbag. Dave opens his mail and tears down a bunch of random stuff.Other Youtubers:https://www.youtube.com/user/DextersLab2013https://www.youtube.com/user/CarlsTechShedSPOILERS:Counterfeit copies of Art Of Electronics!Genuine copy is here:http://amzn.to/1nCmmaKHow to detect the counterfeits:http://artofelectronics.net/the-book/counterfeit-editions/Electromechanical vibrator from a chopper amplifierPolygraph machine amplifier teardownFluke 70 teardownRCA valve oscilloscope teardownAnalog Discovery 2http://store.digilentinc.com/analog-discovery-2-100msps-usb-oscilloscope-logic-analyzer-and-variable-power-supply/Red Pitaya V1.1 Digital Measurement & Control Development Boardhttp://redpitaya.com/Home energy Saver device teardownGuest appearance by Sagan

author: Falkra
author_rank: Regular Contributor
timestamp: February 02, 2016, 09:28:03 pm
content: Nice close up shots, it's not blurred anymore. Nice.Great teardowns, great selection of objects, great to watch !

author: daqq
author_rank: Super Contributor
timestamp: February 02, 2016, 10:04:15 pm
content: Nice mailbag Dave!I noticed a funny thing on the chopper - dendrites! See attachment.

author: cezar
author_rank: Contributor
timestamp: February 02, 2016, 11:30:04 pm
content: Red Pitaya is indeed an interesting device. it can do a 0-50MHz SDR Transceiver! No mention of scope, signal generator and many, many others

author: gadget73
author_rank: Regular Contributor
timestamp: February 02, 2016, 11:36:14 pm
content: I'd be very interested in seeing a comparison of the two USB scopes. I've given a bit of thought to replacing or at least supplementing my old CRT scope with a USB one, and seeing some of the various options compared would be helpful. I like my old CRO fine and all, but once in a while it would be really nice to have direct frequency or voltage readings, or be able to easily snag a graphic of output without trying to take a picture of the screen.

author: dexters_lab
author_rank: Unknown
timestamp: February 02, 2016, 11:42:20 pm
content: Quote from: daqq on February 02, 2016, 10:04:15 pmyea, i saw that too... tin whiskers!the one i took apart had none that i noticed

author: fubar.gr
author_rank: Unknown
timestamp: February 03, 2016, 12:57:46 am
content: There was a cap (or was that a MOV?) that looked like split in half in that Fluke multimeter.

author: EEVblog
author_rank: Unknown
timestamp: February 03, 2016, 01:05:22 am
content: Quote from: gadget73 on February 02, 2016, 11:36:14 pmAre there any other directly competing ones? Not talking no-name ebay ones.

author: gadget73
author_rank: Regular Contributor
timestamp: February 03, 2016, 01:34:03 am
content: Quote from: EEVblog on February 03, 2016, 01:05:22 amOnly thing I know about USB scopes is they have USBIts an area I've done precisely zero research on. I just find the notion of being able to see a display on my 32" LCD monitor with software analysis and data readings right on the screen to be interesting. I don't know if one would do for me though. I mess with tubes for audio and radio work mostly, so RF and high voltages would have to be something it does.

author: HAL-42b
author_rank: Frequent Contributor
timestamp: February 03, 2016, 02:57:24 am
content: That polygraph is obviously designed to intimidate with it's sciency look more than anythingAlso it was fun watching Sagan learn the word Scam.

author: AF6LJ
author_rank: Unknown
timestamp: February 03, 2016, 03:51:33 am
content: Good Stuff.

author: mtdoc
author_rank: Super Contributor
timestamp: February 03, 2016, 03:54:19 am
content: In addition to making polygraghs, Grass Instruments has been a high quality maufacturer of nerve stimulators used in research and teaching labs since the 1960s. I recently bought one of their classic SD9 stimulators on eBay. It's fully isolated, so safe to use with human subjects. It has a well engineered modular design.

author: scopeman
author_rank: Frequent Contributor
timestamp: February 03, 2016, 04:54:30 am
content: Hi Dave,Great mailbag. The Fluke 73/75/77 are great meters. My dad gave me a box full of mistreated and dodgy ones years ago.Usually a cleaning some Caig DeOxit on the switch and a new battery fixed them up.At one time it cost more to have them calibrated a few times than buying new meters so many tossed them and bought new.The only real problem is the zebra strip connection to the display. It appears that yours may have that problem. Just clean the strip and the display and the PCB to zebra connections with alcohol and put it back together and it will still be good until Sagen gets to college. If you put one of those 9V lithium batteries in the meter it will probably still be ready to use when he starts his first circuits lab around 2030 or so. Earlier if he skips a grade!Those meters were shipped with the carbon zinc 9V batteries IIRC. They would run the meter for 2000+ hours no problem. I think that is what I liked best about them as well as their phenomenal Fluke stability. Rare to see the CZ 9V battery leak. Alkalines do! I believe that lithiums do not. You can find them in the big box hardware stores as they are used for smoke and CO detectors.For the person that was asking about the slot in the MOV. This was standard practice to cut a slot to create a spark gap. That could be just a capacitor with a spark gap cut. These work to ground the zaps just like the old Frankenstein movies.The case screw design is called Plastite(R). It is a dual helix screw designed especially for plastics. A patented design that costs more than the average screw. The hint to keeping the threads in the plastic case is to drop the screw in and rotate it counter-clockwise ( it is CCW in Oz is it not?) until the screw drops into the thread, then turn clockwise to tighten. I do not remember having any units with stripped threads. However I have seen some with broken stops for the rotary switch. A cure for that is to pop the actuator off of the housing and use a pin vise to drill a small hole where the broken stop was. Then use the cut head off of a small finishing nail (you need to retain part of the shank) to create a new stop. Simply heat the pin with a soldering iron at a low temperature until it sinks into the plastic while guiding it into the hole. Once cooled you will have a new stop.Overall the 75/77 is one of the finest and simple meter designs out there.Something Sagan will appreciate when Dad is old and grey!SamW3OHMOwner and Moderator of the independent LeCroy_Owners_Group on Yahoo! Groups

author: mtdoc
author_rank: Super Contributor
timestamp: February 03, 2016, 05:28:10 am
content: Dave,Yes, please do a comparison of the Analog Discovery and the Red Pitaya - including the software! These are much more than just USB scopes as you know.Also - a side by side teardown comparison of the Analog Discovery 2 with the original AD if you still have it. I believe the only major hardware difference is the addition of the external power input to provide more power for the 5V power supply - but it would be good to see that confirmed - and see what other changes they may have made to the layout.

author: Stonent
author_rank: Super Contributor
timestamp: February 03, 2016, 08:00:32 am
content: I noticed these things:

author: Yansi
author_rank: Super Contributor
timestamp: February 03, 2016, 10:15:24 am
content: Quote from: fubar.gr on February 03, 2016, 12:57:46 amSpark gap

author: dexters_lab
author_rank: Unknown
timestamp: February 03, 2016, 11:10:49 am
content: Quote from: mtdoc on February 03, 2016, 03:54:19 ami hear the stimulators are quite sought after

author: EEVblog
author_rank: Unknown
timestamp: February 03, 2016, 11:18:44 am
content: Quote from: Stonent on February 03, 2016, 08:00:32 amYep. totally missed that.

author: DuraAce
author_rank: Newbie
timestamp: February 03, 2016, 07:37:16 pm
content: Dave, it looks like your investigation of the solar panel caused too much UV radiation and lead to a sunburnor was it the beach. O0

author: KenGaler
author_rank: Contributor
timestamp: February 03, 2016, 08:25:01 pm
content: I'd like to see a comparison between the Analog Discovery and the Red Pitaya also.I just bought the Red Pitaya fm Mouser but as it turns out the hardware is NOT open sourced, just the software. You can't get a schematic.Ken

author: Cerebus
author_rank: Super Contributor
timestamp: February 04, 2016, 01:25:51 am
content: I had one of the Sinclair Cambridge calculators in around '72 or '73.There were two versions, the regular four function one with an equals key and the 'Scientific' which had trig. functions and was RPN. Both came as either assembled and ready to go, or as a solder it yourself kit for a couple of pounds less. You can probably guess that I had the Scientific in kit form.Ian

author: Len
author_rank: Frequent Contributor
timestamp: February 04, 2016, 01:57:13 am
content: Quote from: Cerebus on February 04, 2016, 01:25:51 amSo did I. I felt quite a pang of nostalgia seeing one here.

author: Fungus
author_rank: Super Contributor
timestamp: February 04, 2016, 05:38:25 am
content: Very interesting:http://righto.com/sinclair

author: Brumby
author_rank: Unknown
timestamp: February 04, 2016, 06:10:09 am
content: Quote from: Fungus on February 04, 2016, 05:38:25 amThatwasinteresting. Thank you!

author: Fungus
author_rank: Super Contributor
timestamp: February 04, 2016, 06:22:14 am
content: Quote from: Brumby on February 04, 2016, 06:10:09 amAlso:http://www.datamath.net/Manuals_Others/Sinclair_Scientific_GB.pdfQuote: "...it is a substitute for slide rules and mathematical tables."So while everybody else was trying to produce 8 or 10-digit accuracy, Sinclair was aiming at people who were used to working with slide rules and log tables.Smart move. The accuracy and limited range of the math functions wouldn't be a problem for those people and the price would be very attractive (50 pounds for the Sinclair instead of 300-400 pounds for HP/TI, according to some pages I've seen).

author: ercapoccia
author_rank: Regular Contributor
timestamp: February 04, 2016, 07:41:30 am
content: Quote from: EEVblog on February 03, 2016, 01:05:22 amAnother competitor could be one from the PicoScope's range.https://www.picotech.com/products/oscilloscope

author: Jacko
author_rank: Contributor
timestamp: February 04, 2016, 02:41:26 pm
content: My first car had a mechanical vibrator in it... or rather the AM radio did. The car had a 6v battery and the chopper pulsed the dc voltage so that it could be stepped up to power the vacuum tubes in the radio. Even though I was a teenager, I can remember this because the radio went out, and my Dad traced it down to the vibrator. He bought a new one, plugged it in, and I was back on the road with tunes blaring.The vibrator had lasted close to 15 years, which was a long life for those mechanical devices.regards, Jacko

author: djQUAN
author_rank: Frequent Contributor
timestamp: February 05, 2016, 02:37:44 am
content: Quote from: fubar.gr on February 03, 2016, 12:57:46 amThese are sliced with a saw. I think this was the airgap the sender was asking for Dave to have a closer look.

author: SilverSolder
author_rank: Super Contributor
timestamp: February 05, 2016, 12:19:16 pm
content: I loved Sagan's map for finding the chocolate - "To get rid of it, we just eat it" - Classic!

author: Helix70
author_rank: Unknown
timestamp: February 06, 2016, 05:49:58 am
content: My WDTV also overheats, and is now in pieces in the drawer. The RasPi2 does a better job and cost a third the price too. POS.

author: axismundi
author_rank: Contributor
timestamp: February 10, 2016, 10:35:42 am
content: Just learned that my copy of The Art of Electronics is a counterfeit. Now I'm used to fake products as these became ubiquitous these days unfortunately, but I did not see this one coming!Bought from Amazon UK (seller booksnesence). Filed a complaint and asked for refund.

author: Vgkid
author_rank: Super Contributor
timestamp: February 14, 2016, 07:33:47 pm
content: Thanks for the video. I got a chuckle about Sagan talking about the chocolate.

author: Howardlong
author_rank: Super Contributor
timestamp: February 22, 2016, 05:04:47 pm
content: Quote from: cezar on February 02, 2016, 11:30:04 pmQuote from: KenGaler on February 03, 2016, 08:25:01 pmQuote from: gadget73 on February 02, 2016, 11:36:14 pmFWIW, I have an Analog Discovery (first version, almost identical functionally to the new version bar the variable power source and different enclosure) that I've had for about a years, and a Red Pitaya that I've been using pretty solidly for three days.They are two very different beasts. With the Analog Discovery, you can expect it to work out of the box right away. The Red Pitaya, not so much. As an instrument, the RP is left in the dust by the AD. The RP as it stands is for tinkering by dedicated propellerheads looking for nerdgasms, whereas the AD is primarily a real, valuable and working instrument from the get go. I think anyone proposing to use the RP as a bench instrument as it stands will be pretty disappointed.The secret is in the software. The AD has the best software I've seen on any USB scope, plus you can run multiple instruments simultaneously. The RP apps look very threadbare in comparison, and you can only run one at a time. As an instrument, the RP also seems to like to phone home a lot as part of its vendor/customer tie in. The AD works without any need to phone home: I use it extensively when travelling, on planes, trains etc. The RP would be nigh on useless for travelling, it needs its Ethernet setting up and needs substantial power.Personally I feel that in its current state, marketing the RP's current instrument capabilities as anything other than a development platform with a very rudimentary instrument for beginners is bordering on the disingenuous. If RP invested the time spent on the slick website into the product's software instead, I might have a different opinion.In short they are very different beasts, for different markets, the AD is a true instrument for end users out of the box, whereas the power of the RP is as a development platform for hard core developers wanting to fulfil point solutions.

author: mtdoc
author_rank: Super Contributor
timestamp: February 22, 2016, 07:15:05 pm
content: Quote from: Howardlong on February 22, 2016, 05:04:47 pmThank you for the comparison/review.Your experience with the AD mirrors mine but I've never tried the RP and have always wondered how the 2 compare.

author: broz
author_rank: Regular Contributor
timestamp: April 18, 2016, 12:02:01 am
content: I, too, am looking forward to the comparison of these "scopes" can't quite afford the DS1054Z yet, but I could afford the $99 USD student price for the Analog Discovery, even if it's just to get me by until I can afford the Rigol. Interested to see if it would be worth it to pick one up now, or wait until I can afford the Rigol.