EEVblog

More Mailbag!
Forum: www.eevblog.com...
Australia's first mobile phone call:
• First mobile phone call
SPOILERS:
Electronics Dummy Load and Dave discusses potential technical issues with paralelling MOSFET's
github.com/dang...
www.nupo-artwor...
Atheist Book: Christian Mythology for Kids
christianmythol...
Metal Rectifier, / Selenium Rectifier.
Hornby Triang model train P5A Power Controller.
Gtronics Protoshield Plus for Arduino: www.gtronics.ne...
Mitsubishi MT-398FOR6A Analog Mobile Phone
Swiss Tools Screwdrivers
EEVblog Main Web Site: www.eevblog.com
The 2nd EEVblog Channel: / eevblog2
Support the EEVblog through Patreon!
/ eevblog
EEVblog Amazon Store (Dave gets a cut):
astore.amazon.c...
T-Shirts: teespring.com/s...
💗 Likecoin - Coins for Likes: likecoin.pro/@...

[@kaizen9451]

The critique of that initial PCB was very very interesting Dave. Shame we can't get a full time series/segment. Excellent video as always.

[@dangrie158]

I really liked his DFM Series and the uSupply Videos. I learned so much from them. Thats why I sent the board in: Not just for the tips but also because I would love to have more content like this. Hope he starts a new public "just for fun" Project soon and shares the creation process with us

[@kaizen9451]

Ahh nice to meet the author of the board. I suppose Daves argument against a series of this type is that it is effectively consultancy work - I'm sure something Dave said he wouldn't do.

[@djs5089]

"That's the one with all the shafts. Jeez, they're long too!" ~ Dave Jones 2016

[@Graham_Langley]

Re. the dummy load: The mod I'd recommend is to split the circuit into two (or more) transconductance amps (that's the LM358, MOSFET and Rsense block) run in parallel. That's what I did when I first came up with the analogue version of this cct. back in the early '80s, although I used TIP121 Darlingtons as that's what the firm had in its parts inventory. I've used the cct many times over the years, mainly in test equipment. Neatest one was a self-contained box that ran off the supply it was loading. With careful layout (on Veroboard) the load current was held within 1mA over a 6-30V / 10mA -5A range and it still gets regularly used over 30 years after it was built.

[@stranger7968]

35:04 For those interested, Dave already did a teardown of that Geiger counter in EEVblog #776.

[@vladtepesch27546]

hahaha - your facial expression on the first look on book - great :-D

[@ScottHenion]

Those selenium rectifier had a distinct smell when they overheated. Something us old timers will remember.

[@richfiles]

I have a small collection of the old puppies! I love how they look... I'll never actually USE them though! They really were awful things! XD

[@macro820]

Was just reading wiki on them.. hope you're ok lol "Selenium rectifiers had a shorter lifespan than desired. During catastrophic failure they produced significant quantities of malodorous and highly toxic fumes that let the repair technician know what the problem was."

[@ScottHenion]

***** Yes, the smell is distinct and nasty. Odd I have a welder with two of them that are 43 years old and still work. I had expected to have to replace them but they keep going.

[@ScottHenion]

I don't want to have to recalibrate the control circuits as I don't have the procedure.

[@coyote_den]

"Distinct" is one way to put it. OH MY GOD WHAT THE HELL DIED IN THE WALLS??? is another.

[@MatthewHarrold]

My dad was a "sparky", my eldest son is doing Engineering/Mechatronics, I'm trying to keep up via this channel. Your voice and enthusiasm reminds me of Shirley Strachan (Skyhooks). I'm learning heaps. Cheers.

[@followthetrawler]

Dave, thanks for the link to the Gtronics protoboard - I just ordered one, so their 'advertising' worked! Cant wait for it to arrive now!

[@Zetex2000]

One of my favorite mailbag!

[@KennethScharf]

Wow, that train power pack. I had one as a kid, but the variable voltage was controlled by a sliding tap on the single layer secondary of the transformer (sorta like a variac), but NOT on a toroid coil, the tranny was your typical I-E core. Another winding provided 22vac for the aux stuff. It also had a Se rectifier (FW bridge) and a DPDT switch to reverse direction. Just a suggestion for the chap who designed the arduino protoshield. How about a footprint for the mega?

[@ryanwilson3424]

dave genuino are genuine arduinos. arduino have changed how ever thing works

[@giorgiobiso]

Yes, Genuino is the name used for Arduino marketed in Italy ONLY, due to some mess with copyright and other legal stuff. Look at here: www.arduino.cc/en/Main/GenuinoBrand

[@MaakaSakuranbo]

+BisoTronic Not sure if something changed since 2 months ago, but Genuino is actually for everywhere outside the US

[@giorgiobiso]

Yes, I was wrong. Arduino = USA. Genuino = everywhere else. Thank you for the clarification.

[@allesklarklaus147]

You can get arduinos outside the US, they just come from a different company. They both were the inventer of this arduino thing though, just split up and two members fucked the other ones over and trademarked the arduino thing in italy without letting the others know. Now they can sell arduinos all over the world but not on the US. But these companies wanna join together now or something "for the customers sake" hahaha sure

[@LiberatedMindcom]

Thanks for sharing! LOVE the look on your face before you realized it was a secular book. Priceless.

[@userPrehistoricman]

As soon as I heard the description of that rectifier, I was thinking about selenium diodes. Photonicinduction destroyed some and was surprised at how little power it took.

[@xlfisher]

Dave, Love the EEVblog. Not any good with electronics myself but I love your channel as I find it fascinating. On a side note a lot of European names beginning with J are pronounced as Y.

[@FranLab]

Last Suppahh! Cheers to you Dave!

[@denverdanny3381]

I guess I am pretty randomly asking but does anyone know a good website to watch newly released series online?

[@bobbyzachary2797]

@Denver Danny i watch on FlixZone. Just search on google for it :)

[@PatrickPoet]

I'm so glad you sharpened your knife. It was breaking my heart.

[@cipmars]

Wow, the full kit is only 70 euros! That's GREAT!!!

[@0Raik]

Worth every single freaking tear.

[@cipmars]

+Raik If I had one of those back when I was a kid, now I'd be working for NASA or something! Great learning tool and cheap too!

[@kaizen9451]

Yes I agree! I'm looking at getting one just to support the idea of a well made product including a well designed manual!

[@JerryWalker001]

The un-smoothed controller was an intentional part of the 'design'. The average power drove the motor but the high peak voltage helped to cut through the dirt on the rails.

[@CP140405]

I have a Triang-Hornby HO scale train set from about the same era... early to mid 1970's. The controller for it has a slide switch (forward/reverse) for direction and a sliding/rotary lever for speed control. How I loved that train set.... wonder if it still works?

[@SpeccyMan]

Great mailbag as always. Thanks Dave.

[@briannebeker2119]

MOSFET transistors are resistive devices (they do not act like diodes) and have a positive coefficient of temperature which prevents thermal runaway. Thus with two MOSFETs in parallel, the Rds of the MOSFETs rises with temperature so if one transistor has a lower Rds it will carry more current and thus it will heat up more than the other transistor, but both transistor still carry current. As long as the transistors are nominally fairly close in resistance they will thermally self balance. If one transistor has much better heat dissipation that the other it will conduct more current but because it will be more efficient thus it will do it with at a similar temperature. Using a common thermal path for both transistors does have the advantage that is one portion of the heatsink has better thermal flow then both transistors will benefit to some degree. Improving the thermal dissipation of the transistor with less efficient thermal flow will have a bigger impact on the total efficiency of the transistors than improving the thermal flow for the better thermally dissipated transistor. Power MOSFETs should generally not conduct more than 50-75% of their rated current because in addition to their current rating they need to be operated in their safe operating area. This also ensure that an imbalance of the current sharing should not cause the higher current transistor to exceed is safe operating area. If this imbalance is a result of a failure then the remaining transistor will run hotter but still within it operating specs. BJT transistors lower the Vce with temperature which results in one transistor conducting all of the current because the Vce of the transistor is not reached. Putting BJTs on a common heat sink and using a emitter resistor allows the transistors to track better and ensures the Vce is met by both transistors. Failing to do some could result in one transistor running cold while the other overheats due to thermal runaway. It is however important to drive the gates of the MOSFETs properly due to the gate capacitance. Rapidly turning a MOSFET off that is carrying a large current requires discharging the gate capacitance and the pulling the gate to the same potential as the source. With large currents flowing ground bounce can leave the source pin at a lower potential than ground which can result in the transistor not fully turning off. Resistance and inductance in the driver circuits between the transistor driver and the source pins can cause the gate voltage to rise in reference to the source pin which can cause the gate to partially turn back on. The gate resistors thus can server 3 purposes. The first thing the gate resistors do is slow down the rise and fall of the gate signal to lower high frequency turn-on and turn-off transients. The second purpose is to dissipate inducted inductive currents on the gate drive signal. The third purpose is that the gate resistor can prevent excess currents making their way back to the driver circuit if the MOSFET fails shorted to the drain. Using separate gate resistors balances the gate drive current so they both tend to turn on and turn off at the same speed and you can use higher resistance values for the resistor. Thus a good gate driver for quick switching applications should have a large current sinking capability. Being about to sink 1 ampere or more means the driver can readily absorb gate bounce and can also survive current from a short from the drain to the gate. This also means the driver ground should be star grounded to the source pins. Of course the higher the switching frequency and the higher the currents switched the more important the gate driving becomes.

[@Edu_RJR]

Dave those faces are reeeally lookalikes of almost every person I may know, it's actually very interesting how the artist chose such easily relatable faces

[@Phantomthecat]

The Triang power supply only has to run a DC motor, don't blow a gasket Dave! :). The 15 volt AC output was used for point motors - although you could use the 12 volt DC unregulated supply they worked better (at least the Hornby points did) on 15VAC. :)

[@electronicsNmore]

Good ole 80's "Brick" phones. I remember them.

[@tubical71]

I rememer that Motorola "brick" very well.....

[@sageata_verde]

I know it's a little late for commenting, i just got to this video now (a lot of conntent to watch and so little time) Probably someone already said it but i will say it too...it is a common mistake... is is not HO scale it is H0 (zero) because it is half of the 0 (zero) gauge. Also H0 is not the scale, 1:87 is the scale, but rather the type of rails for that scale. For example H0 is the normal track distance(1435mm), H0m is for the metric gauge (1000mm) and H0e is for any type of narrow gauge(

[@clee1261]

sageverd In the US, it has been HO since at least the late '50s, although your explanation of the derivation (as Half O scale) is correct. But, because early experimenters in HO were forced to use TT gauge wheel sets and drive mechanisms (or scratch build these difficult parts themselves), the actual gauge (the inside distance between the rails) of HO scale track is not 1:87 of the 4 foot 8.5 inch gauge in common use in the US. Excepting the distance between the rails, the scale 1:87 is applied everywhere else. Likewise, the common usage in the US is O scale, as opposed to 0 scale. Because I have been an HO modeler since the late '50s, I don't know for sure, but I think O scale is 1:48, so the "half" of HO is only an approximation, as well. I don't know why HO became 1:87!

[@Les-electroniciens]

Did you get the thumbnail from Luigi Donatello?

[@ChessIsJustAGame]

the train power supply needs to have a lot of ripple. this helps the electric motors move at low voltages. I had an old HO train and decided to mod the power supply to remove the ripple. train would just sit there with increasing voltage then after a high voltage was reached would try to instantly run at high speed. continued experiments resulted in burning the motor. :-\

[@TheChipmunk2008]

one of the advantages of metal rectifiers is they have a very low forward voltage at low currents (not used in the Triang power supply but often used in telecomms)

[@SudosFTW]

checked them episode trips, Dave. better set the episode number clock, seems like the power went out!

[@LucasHartmann]

Is that little pcb with yellow jumpers on the last scene an STM32F1xx board? Any opinion on these MCUs?

[@stuartsmith945]

As bad as those triang transformers were, You pretty much need all that ripple to start the motors in the trains. Is was most unlikely that you would get them to turn on a couple of volts, but a 5 or 6 volt kick was enough to get them going. The average voltage was low enough for slow operation. I remember back in the 70s, controller designs that when started would give a brief pulse of 12V to get the motor turning to guarantee a smooth start. You have to remember that in some cases with a long train, there was a lot of load and bugger all torque available at low voltage.

[@Rizon1985]

The only big thing missing on a feature set like the protoshield plus would be a socket for an ATTiny. But I guess that's the first thing you use the free proto space for then.

[@hannonm]

the heatsinks thermal dissipation is not an issue if the Mosfet is electrically isolated using a plastic screw grommet and a thermal pad on the back of the Fet

[@markwilliammandigers1001]

I had one of those TRIANG things , only without the transformer inside. Used a separate 1A transformer witch also had a selenium rectifier. Used it for my Triang / Hornby train set.

[@kristina80ification]

I remember in the 80s my aunt had a mobile phone in her car for her work and it wasn't even a mobile phone in the modern sense, it was more like a regular corded phone attached to the dash of her car.

[@funkyironman69]

Bloody AusPost sent my electronic back to Italy! Only had 10 days to collect it from the post office and the delivery card slipped down the side of the letter box. So now the same package has to be sent between Italy and Australia 3 times and of course the Italian postal system is the only one that benefits. :p

[@sbrazenor2]

The postal service in the US made the same claim that the internet was killing their business, but now they're complaining that Amazon.com is making it hard to meet volume levels. (Meaning they're overworked.) The USPS is currently working 7 days per week here, with additional business in the pipeline. Maybe the Aussies should look at our postal system for ideas.

[@TheRetiredtech]

You can pull them apart and each plate will "function" as a solar cell. First solar cells I ever played with.

[@leeclark9790]

Dave, is the arduino dev board made by the same dude who did a similar version for PICs quite a few mailbags ago?

[@kraay89]

If I recall correctly, Genuino is the non-USA name for arduino. See www.arduino.cc/en/Main/Products. Oh and I really want that board now! :P

[@drkastenbrot]

yeah, thats so cool

[@JordyValentine]

It's interesting to see the tools for different industries, every time Dave gets screwdrivers they look so dodgy but he loves them. I guess I'm used to higher torque screws haha

[@geronimostade8279]

Hope you're doing well again, love to follow your channel! By the way, no need to teardown that LG TV ;) Cheers and all the best from Germany!

[@JPennDotCom]

Modern DC train supplies use a pulsed current. The oscillating current enables the train to start moving at a slower speed.

[@TombunnyHunter]

"straight to the pool room", I take it that is a reference to The Castle? Great movie. ;)

[@turboslag]

My Father had that phone, as the Mitsubishi Roamer as it was known in the UK. It could have doubled up as good anti mugging weapon!! He had the car kit install too, I think the whole lot came to about £3K with call costs at £0.50 per minute or part of!! Dave is a lucky sod, that screwdriver set is 132 Euro!!

[@John_Ridley]

Got a link to the guy who makes the custom rollup kits of Swiss Tools?

[@John_Ridley]

Holy cats Dave, that's a $205 (US) screwdriver set WITHOUT the customization! www.shop.pbtools.us/All-rounder-Tool-Sets_c463.htm

[@Arek_R.]

All of these european tools are expensive. But they are worth of it if you will use them very often.

[@kagartoe]

Loves me some BP elitist swiss.

[@error079]

Don't forget to give us a review alongside the that Keysight DMM teardown

[@9b85e5da6d]

FSM! Whole new level of respect for you Dave.

[@GadgetAddict]

Why does it sound like the audio was recorded in a submarine on a potato?

[@joecleveland6525]

As in, a submarine on top of a giant potato? Or is the potato the recording device?

[@AmauryJacquot]

the 15v output is used to temporarily energize the points with a push button

[@Erekose2023]

Not sure if anyone has prempted me, and so if a duplication, apologises. The Triang mains train controller, has 3 outputs at the back... variable (reversible) 12 max DC , used to control the train. 15 V AC, used for lights, and when point motors and signals and isolation solenoids became available, for them also The uncontrolled 12 V DC was NOT for lightsd et al. This provided power to one or more sub-controllers for trains, useful for more advanced layouts beyond a simple oval and siding. DUal ovals, intricate sidings for shunting etc, requirted additional controllers.

[@Seegalgalguntijak]

Unfortunately, even if I turn the annotations back on, I don't see the link to the mailbag video with the miniature open source geiger counter that was shown in the outro.

[@Alphasmsn]

What do you do with all the items in the mailbag, do you store them, sell them or what?

[@douro20]

I wonder if there is a similar issue with JFET based voltage references; every one I've seen has had either two JFETs thermally bonded together or two of them in the same TO-5 can.

[@BMRStudio]

Dave, can You offer a a EEVblog bundle pack with all of Your products inside?

[@4BoltClevo]

There should be a spec somewhere for the volume resistivity of the material in the handle (ohm.m). It's kind of useless to talk about two different resistance measurements from point to point unless those two points were specified beforehand and used by both parties.

[@ramrod126]

I still want to pick up a train controller and use my multi-meter to mark out voltages on the dial for testing the LED sets I build for RC cars. Currently I use a converted computer power supply but I need more than 3.3, 5 and 12v.

[@pocoapoco2]

A lot of old motorcycles use a similar looking diode for their rectifiers except there'd be three of them stacked together.

[@billmoran3812]

Funny, I recall selenium rectifiers as the "new solid state" devices. Rectifiers to me were vacuum tubes. Didn't see a silicon diode until the late 60's.

[@Kris_M]

20:00 full bridge, that's why there are multiple plates (and wires)... Otherwise that white wire cross connecting 2 plates on the right would also make no sense. You know a lot but sometimes you get obvious things wrong.

[@SuperAWaC]

oh man that swisstool kit is beautiful. don't wanna know the price, though.

[@drkastenbrot]

~200

[@Arek_R.]

200$+ trololoolll!

[@SuperAWaC]

yeah unfortunately i need to eat

[@milamiglia2437]

A decent screwdriver is just not difficult to make. Don't buy the emperor's new clothes.

[@Arek_R.]

Wiha is also good, they are from germany.

[@TheAngryAstronomer]

I've had one of those triang train controllers! I vaguely remember the track had 3 rails.

[@benedictnothing]

Dave, if I were you, with your knowledge and all this old tech you get sent, I'd start a little business in film/TV prop consultancy! Especially if you gut the things and make screens and lights programmable. There's a great place in London with hundreds of CRTs, etc, that does that sorta thing and they end up working on pretty much everything that is supposed to be set in the 70s or 80s.

[@Chalky.]

It's surprising how clever this guy is because honestly if i saw and heard him for the first time I'd have the impression he'd be only good for cleaning my windows.

[@michaelhawthorne8696]

Loved that Triang PSU (Not the inside though or the Hamerrite finnish lol) Took me back I can tell you. That Arduino kit is just amazing and amazing value too. That 80's advert pic was so funny, the 'Mullet Man had a phone near his feet, it could be used for Curling... lol Nice vid Dave.

[@chargedcapacitorwdasddsaf6833]

Who is the person in the cover art of the first book? I'm new here and don't recognize any previous covers or jokes.

[@GreensladeNZ]

Greetings from the land down under, the land down under. New Zealand! Might send you some kit soon.

[@John_Ridley]

From inflation calculator: $5000 in 1987 has the same purchasing power as $10,820.67 in 2016.

[@ASilentS]

This is China's favorite episode of mailbag.

[@dansanger5340]

You stole my comment before I even said it!

[@vanuitdeauto]

For some reason I think I recognize someone else as well, but I might be wrong. The guy right to the one in white reminds me of an Iranian Canadian electrical engineer.... Do you think the same?

[@PelDaddy]

You really gotta love the stench when a selenium rectifier fails... Poisonous gas cloud of rotten egg smell that lingers in your room for weeks...

[@douro20]

What is the input impedance an that U1461A?

[@douro20]

That thing cost more than the DynaTAC 8000X did when it came to market in 1984. And to think that first cellular phone from Motorola was built to the same standards as military radio sets.

[@oskimac]

very nice that person return the multimeters. I think they're expensive than the micro current.

[@sirflimflam]

12:37 The woman trying to hold that phone is hilarious. You can see it's really awkward to hold with the battery pack installed. I have to wonder why they aimed for the flatter look at a cost in more width than making it thicker but easier to get a grip on.

[@AstralJaeger]

Well Genuino is the Arduino brand for outside the USA...

[@AstralJaeger]

+jonny kotzur he will see it as soon as he visits the Arduino website...

[@JoelHudson]

Cheers all. Genuino is Made in Italy where Arduino is made in the USA! (Just ask Lady ADA of Adafruit fame)

[@AstralJaeger]

well I taught they made it because of copyright problems

[@Drforbin941]

Where can I get one of those driver sets?

[@PinBallReviewerRepairs]

Wow I would love that Breadboard. :) I would use it for my custom pinball machine I am working on. :)

[@TheKetsa]

where is the episode about that tiny geiger counter at the end ?

[@MexieMex]

I wish I could upvote more than once, just for the look on Dave's face when he thought he's been sent some christian propaganda LOL

[@MsHUGSaLOT]

that rectifier looked so WEIRD. How does that even work? Reminds me of home-made batteries made by sandwiching zinc and copper in multiple layers.

[@netsurferx1]

Hollow out that train controller: Instant RasPi housing! (ventilation is another issue, however.)

[@EcProjects]

A dollar for a letter O.o That's cheap ;) Here in Denmark they will soon up the price to $5.5 AUD for day-to-day delivery!!!! Today it is $4.9.. But hey, "only" $1.64 for 3-day delivery, bargain!!!

[@TheChipmunk2008]

yeah let's hope royal snail don't get that idea!

[@JordyValentine]

if by day-to-day delivery, you mean delivered the next day, then that can cost you about $30 AUD if you have to buy the prepaid express post envelope

[@Drforbin941]

Dave...I love your comment about the flying spaghetti monster! I really wish I grew up around people like you. Here in the States it's devolving rather quickly into irrationality.

[@lefermier10]

@EEVblog, if you ever have a second son, I think you should consider calling him Bob. So that your first son could tease him by telling his own son "Bob's your uncle !"

[@phaZed9]

Thumbs up for the book and the basis on that.

[@Morkvonork]

To the first guy with MOSFET problem. Look up this datasheet cache.nxp.com/documents/application_note/AN11599.pdf

[@dangrie158]

Thanks! I'll definitely do

[@fuzzy1dk]

and this: www.infineon.com/dgdl/?fileId=db3a30433e30e4bf013e3646e9381200 mosfets meant for switching is not too happy being run linear

[@IanDarley]

Mitsubishi Roamer, I had one of those, about 30 minutes of talk time on a full charge, down hill with the wind behind me if I was lucky.

[@alicecrawford6048]

Just to note, the Genuino is the real deal when it comes to Arduino boards these days. Trademark kerfuffles caused the original creators to make a new name.

[@sanderkoster9680]

Genuino is the European Arduino name due to copyright and problems within the Arduino group

[@adslf874yti3q7u4hf83]

Oakey. I've been there. Airforce base, bunch of sheep, a church and... not much else.

[@BMRStudio]

Arduino shield, swiss set SOLD! But the swiss set only with geniue EEVBLOG logo on it :)

[@Elavid]

Since they speak German in Switzerland, Jorg would be pronounced like "yorg", and Wien would be pronounced like "veen". Also, Wien is the German name for the city of Vienna.

[@tom7601]

Selenium rectifiers smell like rotten eggs when they die. Back in the 1960s we repaired TVs that had them. A homemade diode rectifier was the usual repair.

[@WreckDiver99]

23:04 - Is that a shout out to Jerry Berg (Barnacules Nerdgasm)? LOL

[@TheKyshu]

You should try using that power supply for Pulse Width Modulation :)

[@meazle]

The link about the book now leads to a spam site.

[@ceilingfansandmorecfam2342]

nise vid..soo i got som boxes full ov serket boards do you want them for mail bag?

[@Mirandorl]

Ello :) I want to buy an oscilloscope. Got enough cash / steady job, want something that will last a few years. Am a beginner but see no point cheaping out for the sake of it. Rigol DS1054Z still the mutts nuts?

[@rodstartube]

what is the etymology for winner winner chicken dinner?