Got an email from a viewer without a KZfaq account: Quote: "The reference in your < US$200.00, 6.5 digit multimeter blog has some really ‘old school’ wizardry in it. Way cool! If you are interested, I would like to point out a few things lurking inside the LM136: First its (surprisingly) mostly a Brokaw bandgap cell. Being National Semiconductor, one would have expected it to be a Widler bandgap cell IF it went all the way back to the birth of the bandgap reference, which happened at National. The Brokaw part of it uses 2 transistors (versus 3 for the Widler) in Q15 & Q16, which are almost certainly laid out with an emitter area ratio of 8:1. If both Qs are operating at the same current, the voltage across resistor R8 will be kT/q * Ln(8), or about 53.44 mV. At room temperature. This is multiplied up via R7, R8 and R10 by 23X, which is about 1.2292 Vdc. This is added to Q17 & Q18 Vbe connected diodes. Assume Vbe = 0.6354 Vdc and you get a total of 2.5000 Vdc! The collectors of Q15 & Q16 have equal load resistors and Q7 & Q8 are the input stage of the op-amp that balances the Brokaw cell. Q1 is the ‘power’ shunt pull down regulator. Actually, this is not quite a Brokaw cell (due to patent concerns), so the tail current of the first stage is NOT derived by reflecting the collector currents back down to the current source that feels them. Instead, a really neat hardly ever talked about ‘Cross-Coupled Cell’ is used to generate a PTAT (Proportional To Absolute Temperature) current at emitter-degenerated Q14. The flatness of a bandgap over temperature is much better when the collector currents are PTAT than when they are NPO. (Note: the ideal TC is process dependent on the so-called ‘eta’ factor which, if close to 2.0, all is golden). This CCC (cross-coupled cell = Q10, Q11, Q12 & Q13) has a difference in ‘bottom’ emitter voltages that is independent of the ratio of left to right collector currents! This happens because the Vbe(Ic) for both Left & right show up in the sum of Vbes on BOTH SIDES! This is so useful, Dave. For example, if you need a really low input or termination impedance and you don’t want to throw current and power at it, this is the cat’s meow. Zin can be Beta/2 lower than Re (emitter impedance). For example, at 1 mA, Re = 25.7 Ohms, but the CCC can have an input impedance of 0.1 to 0.25 Ohms at the same current. Here, those bottom NPNs also have an area ratio (probably 8:1 also) and this makes a PTAT voltage across resistor R2, and that flows into a, ready for it? A Split-Collector lateral PNP! Q9. That produces an equal PTAT current copy that feeds the tail of the lateral PNP 1st stage transistors, Q7 & Q8. Underneath is the NPN current mirror, Q4 and Q6. The next neat trick is that the sum of the current mirror transistors’ current is also PTAT, and that is used to feed another NPN current mirror Q3 & Q5 whose job it is to make the collector, and therefore the base currents of 2nd stage NPNs Q4 & Q6 not only equal but also PTAT. Making everything possible run at PTAT currents keeps all sources of errors essentially constant over temperature, and is almost always exploited. Finally, Q1 is the final stage of the balancing op-amp, and it operates in the shunt mode, diverting any current in excess of the sum of all the other transistor currents, all of which are running PTAT. R1 is a ‘pinch-resistor,’ which gives very high resistance in limited areas but is otherwise abysmal, with wildly varying initial value and horrible TCs. It is used as a fail safe startup circuit and the only reason you can get away with using it is because of the in

The "Dave Effect" will make it impossible to duplicate this kind of a bargain for a while.

I recently read a story about a bike manufacturer from the Netherlands that had massive problems in the US with damaged goods due to shipping. Their solution to the problem was to print a TV on the outside of the package because TVs are expected to be more important than bikes in the US ;) Their returns due to damaged shipments dropped by 80 percent right after that. So you clearly should give any seller from the US the hint to mark the package with "TV inside" or the like to have it shipped without damage :D

And suddenly, the EBAY pricing of Philips Bench DMMs goes thru the roof!

Dave, dont forget to re-label the back. She's 230V now!

I sell on ebay for a living (mostly used items). There's absolutely no excuse for that packing job.

Philips - Made in Holland All those original Philips components... brings a tear to the eye.

Backlit LED display mod next! :D

The reason the packaging was so bad was because it was shipped through the eBay Global Shipping Program where eBay supposedly open up every package to make sure it's the right stuff and repacks it in a much more fragile box... Such a wonderful way to make things easier for consumers.

I inherited my dad's so I had to go take a peek at it... yes, your buttons on the top row are pushed in. Hopefully an easy realignment of the board behind the fascia.

I am surprised that was as intact as it was. If it spent one more day in transit, it would have been destroyed! You got it just in the nick! (Did I say that right? I am in the US and no, I did not box that beautiful unit. I would have put it in a wooden crate! Yes, then shipping would have been much higher.) I am so glad it wasn't damaged badly. Thanks Dave!! Love all your videos.

This was our eBay store. We did not pack it like this, we added foam inside with more wrap The eBay global program repackaged this unit when it cleared customs.

That back to front conversion. Brilliant!

I think all those loose panels when you open it are a good thing - they make for really easy access to the internals. They also are part of the reason it's light for shipping. A couple of screws and it's all back together rigidly. Nice one.

Backlight is burnt out. It's a EL strip and is a pain to replace.... You can get a larger EL strip & cut it down, but IRC it's a little involved (very tight fit) but only the EL strip needs replacing, the HV power supply is fine. BTDT on a similar display but on a power supply. That old Philips stuff is great quality overall, except the backlights...

I think the panels are designed to be swap-able depending on where you want your jacks. If you want rear facing jacks for continuous monitoring through GPIB then you can swap the clean panel to the front and the jack panel to the rear.

Inspired by your previous video I bought a PM2535 for 100 euro.

Dave, You can see that made in the Netherlands stands for perfect quality and ingenious solutions. And still works perfectly after 25 years.

Old PCBs look so beautiful, all those colors and different shapes of electronic components, nice!

Thank you very much for this video, dave! I love my several phillips - now everbody can understand why. these are rock solid units without too many flaws - when you're not so fancy about fast sampling and brilliant displays...

I've gotten stuff from China that was better packaged than that. Yikes! All things considered though, not a bad score!

Ability to individually calibrate ranges is wonderful, since some old precision meters sometimes required something silly like 1000V DC 30 ppm and even if you never used the range you still had to put at least something around 1kV DC during the cal process.

3:17 That's not a date code. It's a 12NC code which Philips has been using for all their components and devices since the 1960s. They're always grouped in XXXX-XXX-XXXXX format. The transformer, EPROM and Reed relays have them too. You're not far off with the date, though: Judging from the dates on the chips, this unit was made at the end of 1992 or the beginning of 1993 just before Philips sold their measuring instruments division to Fluke. The factory was in the city of Almelo, The Netherlands; that's why you see that word all over the place. Great to see all the Philips branded stuff inside; back in the day, they made everything themselves. I wouldn't be surprised if that 8032 microcontroller came out of a Philips factory (they had some sort of unlimited license on the 8032, that's why so many Philips things have them), and I know they were good buddies with National Semi so no surprise seeing lots of NS chips show up to the party.

Your forum has led me to browse eBay a few times a week for the hope to score a crazy deal on a sexy thermal camera.

I have a similar vintage Philips oscilloscope, it is very light for its age which I'm grateful for now each time I lift it onto my work bench.

it survived the transit in that flimsy carton - very sturdy design.

This was the first "high end" multimeter I bought back in the 1990s and it still works fine. Nice little meter.

Your narration is very good. Makes boring things a little bit interesting. Thanks!

It was probably re-packaged by ebays global shipping program - that is unlikely the packaging from the original seller

What a score! And what a great design allowing the terminals to be flipped between back and front as per your preference. Philips, one of the best electronics companies. Shame they aren't everything they used to be. They used to make awesome TV's as well, sad we don't see them anymore.

LOL, I was screaming at you when I saw the back of the unit for the first time ;-) Nice unit made in my home country.

Excellent example of how all was made back in days - with thought for long device life.. About jacks panel swap to front - yes, i'm noticed that because plastic part forms were identical and DIN 5 pin socket was in booth sides, but i didn't scream, just waiting till the end of video to see - i need to say about that or not.. :D Anyway, great teardown and test video. Love these old testgear videos.. ;)

My father used to sell some very high-end studio monitors that were imported from England. One time he got a shipment where a forklift fork had quite literally gone through the speaker cabinet. So sometimes it goes beyond doing a good packing job.

Handheld meters reviews and teardowns please Dave! Great addition to the lab!

I always explicitly state to wrap on plenty of padding when buying things.

The issue with the DMM screen looking dark on the camera is probably due to a polarisation filter.

Actually it’s “US$150 just-barely delivered to Australia!”

6:26 It may have been bought owned by a Yank. But according to that transformer sticker it was made in the Netherlands. (at at Philips plant in Almelo , near the town I grew up in) So it's been the world over now.

21:44 It looks like the colors of the wires match the colors on the connector panel. (black=black, grey=striped black, ...)

Amazing video love how you can swap that port arround haha

I got a box like that once, only the box box was completely empty. The postman delivered a totally empty box that was open at the end. Did get my $ back though.

The resistance specs are for 4W mode, not 2W mode. Also, the standard may not be exactly nominal-- so the difference between the 4W reading and the calibrated value of the resistance standard is what you should be looking at. The resistance in the leads must be nulled out to check 2W mode.

Think the fuse is meant to be replaced just by getting the front/back-plate out while everything is inplace. So maybe some tongue twisting required when the case is closed ;) and then the wires pop off...

Ah, I see the problem. That thing lost its parachute. I've had things arrive looking like they'd been wrapped in cloth.

I looked on Goo image, and unfortunately it looks like they don't have a backlight. Also the top buttons were pushed in compared to that black version at 28:40

I got slated once for doing parallel meter connections measuring voltage in a review video but I didn't see anything wrong with it, good to see you do it too!

brilliant design with the swapable input panel

You STOLE that Meter! Beautiful! Love it. Connection panel on front, priceless. I'll bet that was $2500 new. (Just guessing).

10 seconds in and I'm going to guess that the seller had absolutely no idea how to properly package equipment. That meter has to be damaged somehow. Edit: The condition of that meter must be a testament to the build quality that Phillips put into it.

I just picked up an HP 16500B logic analyzer mainframe with a 16510A logic analyzer card at my local retro computer meet last month. Manuals and software are STILL available online.

Fun fact: stevedores love to sit on packages marked "FRAGILE". Second time viewing this video. Every time Dave does a bar napkin calculation, he says that any confounding variables that are a couple of orders of magnitude below what you're interested in can be safely ignored, yet here we are again with a bit of kit that measures well into the noise. Other than using trace resistance to track down rail faults, I can't imagine why a general purpose electronics engineer would need such resolution in a piece of test equipment.

7:14: "It's not terrific!" You've got to applaud this sort of ingenuity. Saves on costs, manufacturing, shipping, assembly - I bet you are glad you don't have to unscrew 4 more screws. It should last longer too (as long as you don't plan to bash the thing) and when it eventually breaks it can be recycled and a replacement can be easily made (esp. if you own a 3d printer). One of the cases where use of plastic over metal wins.

Hola EEVBlog! Kinda hard to tell from the footage but I think I have seen those power connector power switches in old computer power supplys here in the states. If it is the same style, the little 115-230 switch actually opens another lead to the primary, which basically jumps the connection like you did with solder. Thanks for your videos, you rock!

Dave don't forget to put a sticker behind over the 115V selection.

That LCD definitely needs a soft green backlight

item description " plate turquoise swirl' LOL

i cant believe they didnt at least attempt some sort of adhesive on the back of the probe plug panel plugs.. thanks for the video man

Doublewrap, Double box, Cover outside with ducttape (completely wrap it). It's THE way to guarantee your stuff arrives in good nick. Any overseas shipping, I communicate with the seller about their packing method, and if it's not up to snuff, I ask for the shipping charge to be doubled if they go out and buy a roll of ducttape and an extra box. Never had issues ever.

"You don't want to just whip it out!"

22:49- Looks like they found a 'killer app' for this "Tuner Switching Circuit" :)

Hey now.. I got the same meter with jacks on the front. $120CAD shipped. Not overly impressed. Display is hard to see. Power switch is a pain in the ass to get to. The 6.5 digit spec at that price is awesome.

The display/button board looks bent back somehow. The uppermost buttons don't stick out as far as the lower ones, although they look like they should.

Finally! A story with a happy ending. I feel more like I do now than I did when I first got here.

I see a Fluke and Philips sticker on top of it. Nice little bit of kit.

I worked for Philips Test & Measurement USA 1975-1979. The stuff was amazing. The analog scopes we imported for the USA market were as good and often better than their counterparts from both HP & Tektronix. This from the perspective of working for Tek from 1972-1975.

Beautiful piece of equipment.

Good stuff Dave

I was also wondering what that long blue tube component was. After you showed off the reed relays, I saw the blue tube again, and before you worked it out, I was saying to myself "that's gotta be a BIG reed relay!!"

The bubble-wrap-whacked-in shipping works well enough in Muhurricuh.

Lovely pickup! I quite like Philips stuff.

Coils on reed switch as relay. Most of early Philips CD player used it as muting switch.

I bought some retro Macintoshes from Ebay 10 years ago shipped internationally from the US and they arrived packaged the same way. Hilarious.

Nice meter Thanks for sharing :-)

you should try tilting the camera left or right, the darkness may be a polarizing lens orientation vs the LCD glass

Maybe there's a polarizing film on the display glass. It would be interesting to rotate the camera 90 degrees and see if the apparent transparency changes.

At least it came out the right way up for the destination hemisphere! Lowest cost shipping? Well, duh yes! They hardly broke the bank on the packing!

Dave try to make a comprehensive teardown and analysis video of one of those R&S power supply. Comparison with one of the linear power supply in terms of noise performance would be nice touch and also how they remove so much switching noise from the power delivery would be nice thing to watch and learn. In depth Technical Tuesday video.

Good video as always Dave. It would be nice to see a video on how to change those battery backups without losing the calibration data. Is is simply a case of supplying a separate supply to replace the battery voltage and using a battery powered (or non grounded) soldering iron so that you don't short out the voltage rails when touching the contacts with the iron?

The package at the begin looks great...

You can remove the jack panel with 1 screw to change the fuse. No need to tear it down.

There is what appears to be a cold solder joint on the ground lead at the back inside of the unit.

great find

I got one too but it's still not functioning. I have a post on the subject in the blog. Recently i turned on the repair and we'll see ...

looks to me like you might be able to swap that connection panel with the blank on the front somehow. That'd be cool

Spectacular video Dave, thanks for that. I will say, for the home gamer, this is a shit ton of meter for that money. My god, could someone really do better? I would like to see a revisit on this and see how it tests out overall. I am damned impressed to say the very least!!

That YUUUUP isn't that Dave Hesters' business from "Storage wars"?

When you did the teardown, I kept expecting you to fix the pushed-in buttons for the entire video.

Looks like the PCB for the keyboard is pushed back at the top. I am surprised you did not fix that when it was open!

the construction isn't bad at ALL actually contrary to what you're finding there - when you fit all the parts together you'll find that all the plastic pieces operate in TENSION and everything should be very well supported inside (see the card edge connectors etc that fell out in the beginning of the tear down - you need those to 'pre-load' the other parts structurally

Is "through hole" the right term for the resistors and other components on the board? They're beautiful.

was expecting magic smoke when you plugged it in especially when you showed how it was packed not knowing if anything was damaged during shipping

The fuse can be serviced by just taking off one screw and removing the probe connectors panel.

Even the professional ones send you a too big box, filled only a little bit with chips OVERSEAS! So the Rohde & Schwarz CMD80 was flying around in the box. End result was, damaged feet, damaged protective front cover (that saved the LCD), damaged rear bumpers. The instrument was an older US type CMD 50, so totally useless by itself, but pretty interesting for spare parts. But the interesting spare parts where covers, bumpers, feet, LCD and power supply. So only LCD and power supply where left. I filed an ebay claim with very expressive pictures but the company filed a counter-claim, even I sent pictures. And as ebay requested me to send another set of pictures within three days, in the middle of my vacation... So I wrote it off.

Can't complain about the packing; when the box looked like that and the meter arrived un-broken.

Did they drop that box from 30,000ft?

Stay on subject Dave, now i just want some fish and chips !

In the LM136, you'll find a departure from the expected Widlar bandgap design in favor of a Brokaw bandgap cell, likely due to historical considerations. This configuration employs two transistors with an emitter area ratio of 8:1, resulting in a voltage across resistor R8 of approximately 53.44 mV at room temperature. This voltage is then amplified by a factor of 23 and added to the Vbe of diodes Q17 and Q18, yielding a total output voltage of 2.5000 Vdc. Moreover, a unique Cross-Coupled Cell (CCC) generates a Proportional To Absolute Temperature (PTAT) current at emitter-degenerated Q14, enhancing the temperature stability of the bandgap reference. The CCC's design allows for a low input impedance without significant power consumption, making it advantageous for certain applications. Additionally, the use of a Split-Collector lateral PNP (Q9) further contributes to maintaining PTAT currents throughout the circuit, ensuring consistent performance across varying temperatures. This PTAT current approach minimizes errors associated with temperature fluctuations. Furthermore, transistor Q1 functions as the final stage of the balancing op-amp, operating in shunt mode to regulate current flow. The inclusion of pinch-resistor R1 serves as a fail-safe startup circuit, compensating for its inherent limitations through circuit design considerations. Overall, the LM136's innovative design elements, such as the Brokaw bandgap cell, CCC, and PTAT current implementation, underscore its robustness and reliability in providing stable reference voltages across a range of operating conditions.

Next video: i think the front PCB that carries the buttons and the display needs to be wedged back in, maybe a plastic mounting post broke or maybe it simply became unclipped. While at it, maybe an LED strip or something to make the display more legible. Just a bit of light entering from the sides can make a difference.

I have had stuff arrive in a box with no packing what so ever.... the box was usually 10 times the size required. Some things survived believe it or not and some packages became a rather large maraca....

Yeesh, that packing job is horrific, kinda surprised how good it looked out of the bag, and no rattles either ;)