We have bunches of these machines at work. The software is a *real* pain. The vendor's attitude is basically, you buy the instrument, and the software is included. With some devices they won't even let us do the software install, they ship an imaged hard drive with the machine! What's really great is when we have to replace a perfectly working $25,000 camera because the vendor doesn't support any Windows beyond XP. The button is for use by the patient. They press it when they see a light. When the light is outside their field of view, they don't see it and don't press the button :) Interesting use of a paper tape reader head!

It has a Geneva Drive. Like movie film projectors.

That style of device is still used, although the new ones have individual LEDs for the dots, and the whole thing controlled by a computer and standard monitor. The button on the cable is to press when you see the dots, each one has various quantities and the intensity varies each time as well. The background is dimly illuminated, probably to deliberately reduce the contrast between the backing and the illuminated dots.

@mikeselectricstuff

2 жыл бұрын

Don't think that's the case for this unit - the coily cord was definitely open-circuit, and there was no apparent user interface to relay the result of any button-press.

That long bodied bulb is the used in otoscopes (for ears), so I'd bet money on it also being the same bulb used in ophthalmoscopes. Very bright for its size and age. It was quite some time before they were replaced with LEDs.

@Some_Beach

2 жыл бұрын

Isn't it crazy how we had to have specific special bulbs for things like this and other things, and leds came in and totally wiped the floor

Another reason to mount the trigger transformer on the tube assembly is that they are a fairly common component to fail due to their small size and the high voltage.

@yanikkunitsin1466

2 жыл бұрын

So, how is it in Scotland/Main?

Solid state physicist here, just discovered your channel and it's a real treasure trove of refined and obscure electro optical and electronic equipment. Wonderfully narrated, delightful.

I had to take one of these "tests". The remote trigger is for the patient. Assuming it was a similar test, I was asked to stare at the center, trying not to move my eyes, and press the button every time I saw a light. You reflexively glance toward each light, but that didn't matter - it proved the point that you saw it. You wouldn't get the next light until you were staring at the middle again. Not sure if that was automatic, or the technician watching and advancing the test.

@tekvax01

2 жыл бұрын

yes, i too have had one of these tests many times at the eye doctor.

@didaloca

2 жыл бұрын

I hate those tests, visual snow makes it difficult to distinguish the lights.

haha blimey that was quick±!!±!!!! i'm glad you did this and glad its gone to a good cause ha. when i opened the back and realised how preposterous it was in there i didn't dare yank it to bits. if no one ends up going for the whole piece! and you don't want it keep hold of the light pattern bits and bobs! i think that was the best bit of it and i would like to wire it up!. but like i said if someone takes the whole thing no worries, it would be better that way :D.

@mikeselectricstuff

2 жыл бұрын

I did think it might be fun to connect a binary counter to the LED board to sequence all the patterns.

Of all the tests at the optician, that was the one I liked the least. I could never pay attention and focus long enough to realise when an LED had flashed. When you saw a flash you pressed a button to register it. The last one I did was done right next to a window with sunlight streaming into the unit and I couldn't see a thing, then the lady just made a "hmm" noise, and said it was fine. Specsavers don't use these any more. They use frickin' lasers to create a 3D map of your eyes instead.

@micahnightwolf

2 жыл бұрын

The machine that blows a puff of air to test the internal pressure of your eyeballs was the absolute worst for me.

@gorak9000

2 жыл бұрын

@@micahnightwolf Yes, that thing is horrid, and makes your eye tear up, and then AFTER that, they do the vision test, with your eye all teary and not looking like it usually does. Why don't they do that BS puff test at the end?? Annoys me to no end every time I go

@MaxNippard

2 жыл бұрын

@@micahnightwolf the machine the air puffer replaced was way worse. The optometrist would place a piece of paper soaked in a liquid (to numb the irritation I think) onto your eyeball then push a probe against the paper to physically measure the pressure.

@simonweel7971

2 жыл бұрын

@@MaxNippard They still do that, although the piece of paper is replaced by a drop of stingy fluid in your eye to numb it. And then they push a probe in your eye.

@robbillington3594

2 жыл бұрын

Unfortunately OCT "3D" scans do not replace perimetry aka visual field tests in glaucoma screening and certainly not diagnosis. I fear your optician's practice is taking the easy, theatrical route rather than the best clinical practice way.

6:45 I believe that mechanism is called a Geneva drive? Most well known in film cameras and film projectors. Interesting that it has five spokes rather than four.

its so marvelously over the top for what it is. million dollar indicator light.

I enjoy pulling that sort of stuff apart. I was presented with a pallet of opticians stuff and had a lovely time trying to understand what each item did. As you say a lot of this stuff is a challenge to get apart, makes you feel for the poor onsite engineer charged with supporting this stuff. I keep some bits of optics and mechanics for future projects but on the whole its scrap, great shame when you know the precision involved in much of this. Thanks for sharing, Ive never seen one of these before

Love these tear down videos Mike!

I'm the bloke Sam bought that thing off, I remember why I sold it now! It looked like being a nightmare to get into. Looks like it was designed by first year uni students rather than a big company, just a little bit Heath Robinson isn't it🤔

@saa82vik

2 жыл бұрын

Indeed. The optomechanics looks particularly coarse and overblown.

Happy New Year Mike. Thanks for the teardown! 👍

Looks to me like the company that made it (which are still going by all accounts but seem to now specialize in Mucus Clearance) got an Industrial Designer in to make it look sexy and then it was left to the engineers to shoehorn everything into the box anyway they could. I also suspect there was little in the way of new design or radical thinking and it is an evolution of the previous design because there seems to be many things that, with a little thought, could have been improved and made more cost effective. I suspect that foreign competition had not hit this sector when it was designed so price wasn't a major factor .

Hey Mike, I love the videos you post! Keep creating the awesome content! :)

Clear case 3mm LEDs, in 1986 ? I was thinking they did appear at least 10 years later. BTW I add this video in my "weird stuff teardowns" playlist :-D

@mikeselectricstuff

2 жыл бұрын

Definitely - 3mm red LEDs were certainly a thing then, clear case might have been a special order

Oh gosh I spent two years of my life visiting hospital weekly for this machine! Long story short I was having massive vision disturbance following several operations on my back. Docs were concerned enough to have me visit weekly for tests. (I'm fine now. The problem gradually went away) The machine was annoying. A bit because it was every week I used it and also frustrating because I could easily tell doctors what they were using the machine to find!

@skussy69

2 жыл бұрын

@@justotalkalottashit8392 what even is the point of your comment lmao

Looking at that chin rest reminds me of the glaucoma test i need to get at the eye doctor every 6 months and its triggering

The Humphrey field test. Hated this machine as a kid. It was always turned up so bright inside I could barely keep my eyes open.

i immediately was like, didn't i see this thing on lmnc before?

We used to use RS and Farnell for R&D but for production they could not be used as they could not provide the required traceability. For medical equipment you do not want to be changing the components listed on the critical components list too often due the retest and paper work costs. So traceability is a must with no supplier components swaping for a different manufacturer. I expect the optic's don't get updated very often due to the large costs involved.

If you have a flash tube with unknown specs, is there a way to get a rough estimate for the right capacity of the capacitor? Like a relation to length and/or diameter? Because I have one lying around, very similar in size to the one in the device above, except that it's not just a single U, but 1 1/2 turns.

@mikeselectricstuff

2 жыл бұрын

Keep adding til it explodes, then back off a bit... Or if you only have one, compare it to something of a similar size that specs are available for.

It's interesting to see things done with no microprocessor, but with use of IC logic like BCD encoders and LEDs. That was a slice in time mostly in the 70's, but I imagine hung on longer in small companies where nobody had firmware skills. And redesign is something your avoid. Possibly you don't even have a designer on staff. I've run across companies that are selling an old design and don't seem to understand how it works.

Zeiss still makes CRT-based visual field analyzers.

I've had eye problems for years and have stuck my head on one of these and similar quite a few times. Quite stressful actually because the older units produced quite dim dots and you find yourself back-focusing your eyes and losing the distance where they sit........you don't stand a chance of seeing them if they are way out of focus! One small trick on the later models I've used was that the operator could be seen out of the corner of your eye pressing the button so you got a heads up that things were about to change rather than just random unknown timing.

@TheFool2cool

2 жыл бұрын

If you find yourself cheating at an eye test.... You're probably only cheating yourself

@IanScottJohnston

2 жыл бұрын

@@TheFool2cool I had a conversation afterwards and said to the optometrist "that machine absolutely sucks"......and she said "yes, we try to give the patients a helping hand" ......meaning the heads up clicking the switch was on purpose! (but still had to tell them how many lights I saw). Subsequent machines were a LOT better and no "cheating".

@plainedgedsaw1694

2 жыл бұрын

@@IanScottJohnston I have slight suspicion that the doc was actually pressing what patient should be pressing to pass the crap quickly. Everytime I did this the doc just left the room and returned to print the results.

@IanScottJohnston

2 жыл бұрын

@@plainedgedsaw1694 probably right.

Pity the poor chuff that had to assemble that thing at the factory 😬

I have taken apart similar optical test equipment, and the build quality is the same, though the older units used a lot more brass parts in them. High price to buy, which more than covered the moulds needed for the plastic, as the most expensive part would be the certification of the unit by the appropriate authorities. Very likely a cost reduced version of an older unit, with plastic parts replacing the original parts, which likely were hand machined out of brass plate in each case. Then a new batch was ordered, and they decided to cost reduce and get rid of the brass parts, and went to plastic instead. These typically last 30 years or more, so yes different ages of design parts, using stuff they already have in house, and the special lamps are a very common thing, pre focussed optical parts to make it locked in to the original supplier, and also making service tech life easier, as they have a quick expensive service call. Yes optical encoder is the reader from a teletype machine, or at least started off as one, just on a special PCB, Lamp assembly yes loose socket pins, likely on the high current leads to the flash tube.

Mike always seems to be trying to speak quietly. Reminds me of when I used to disassemble my Dads radio, speakers, amplifier just to see what was inside. Thats how I'd be narrating a video back in 88!!

2 videos in a week? I thought Christmas was over.

Very refreshing! Thanks for sharing!

I did that once. You need to stay in a very dark room before starting this exam, if not you'll fail it. Also takes 2 tries to pass it many times.

"This is one of the most annoying things I have disassembled". Me, thinking back to the first video of yours I watched, and wondering if this really compares to the satellite uplink buoy teardown? :)

Hello, AUIR3315 and DMG4822SSD are obsolete and hard to obtain nowadays. What components do you use now for 48/96 LED drivers?

@mikeselectricstuff

2 жыл бұрын

Haven't built any for a while & have some stock - not looking forward to when I need to do a new batch...

@Mister_Brown

2 жыл бұрын

the dmg4822ssd-13 is still in production, BTS50080 is probably your best bet for replacing the auir3315 lower on state resistance and different programming ranges but otherwise workable

@Sculptoroid

2 жыл бұрын

BTS50080 does not have adjustable current limiting like AUIR does (down to 3A). I'm working on a HA controller for CC 24V LED lights with 8x4 channels, and I was impressed with Mike's design. Besides that I will implement another 8x4 channel controller for 24V devices/CA LED lights.

Square peg, round hole engineering. Very interesting teardown.

Don’t assume it’s no longer used. I’ve encountered very similar machines to this in the recent past in High Street national chain opticians.

@chtech0710

2 жыл бұрын

Me too. A few years ago i went to a local doctor because some eye problems. I had to do this kind of test with a similar looking machine, but it was way bigger and still from the early 80s. Why the 80s? Because the doctor was controlling the machine with a light pen by a green CRT display in the back.

Designed by someone who was never going to service it, much like some stuff i came across in the electrical industry.

It seems to me the most expensive part was the custom geometrically overly complex fiberglass case. Why the hell go to the expense of such a weird shape, when you haven't really bothered with any aesthetic design, why not just get a rectangular metal enclosure and be done with it? Especially making forms for something that low volume?

@mikeselectricstuff

2 жыл бұрын

I don't think Fibreglass is all that expensive - wooden tooling. Anything vaguely medical needs to look the part to inspire confidence

@jovangrbic97

2 жыл бұрын

@@mikeselectricstuff True to looking the part, but I'm not sure you'd get away with just wooden molds for the fiberglass layup. Especially you would never achieve such a smooth outer finish on a pure fiberglass body. You'd almost need a vacuum molded piece of acrylic or other material for the outer skin, under which you lay up the fiber sheets and impregnate with resin. Not something they'd be doing in house, and contracting out for a short run would cost more than some precision cut steel plates that bolted together nicely. Not that weight is much of an issue for a stationary device as this. Just a question I'd like to put to you Mike if you don't mind, seeing you're the lighting expert, I've come across some Lidl Christmas lights that are a chain of 200 addressable LEDs (25s8p) but connected to the power/controller box by only 2 wires, which carry 24Vdc power, but also carry superimposed serial data (signal high 24V, signal low 12V) for the addressable part, and the single LEDs are 'normal' looking 5mm strawhats with just 2 pins, but obviously an integrated IC for parsing the serial data superimposed on the power feed. Capable of independent colors, patterns, dimming, some being off... Have you come across this kind of system before, and might you be interested in knowing more? Cheers!

@SeanBZA

2 жыл бұрын

@@jovangrbic97 Production volumes would be in the dozens per batch, and easy enough to get any competent boat builder to turn them out, as it really is just a case of having a wooden mould, a lot of paste wax to coat the inside, then spray the gelcoat into the mould, let it cure, spray in the colour in a few layers, then go with chopped strand mat to make the case, and roll it down. Then pop out the next day and do the finishing. 5 moulds will turn out 5 every day, so a 2 week run will give 50 cases, and likely the company kept at least 50 cases in stock so they could make the machines to order. Going to bet they made different machines, that used the same PCB sets, and just had different housings and functions, which accounts for all the odd design types in there, using stuff already in the stock system to make, so you needed the minimum number of new assembly parts. Might have a factory that had 10 people in it full time, making machines to order, and the rest of the time running as service centre for them as well, for those already out there, probably with one or two field techs, who came in and did a day of assembly when not out.

@grahamparks8885

2 жыл бұрын

@@jovangrbic97 There's a video about similar lights here kzread.info/dash/bejne/iYCM0KWaiLudp5c.html

@jovangrbic97

2 жыл бұрын

@@grahamparks8885 I've seen Julien's video, but this product is *different* , his lights could only ALL act in sync, same colors, pattern at the same time, *MINE* can have individually different colors, patterns, dimming, even some being OFF while others are still lit. This I think is a brand new consumer product and would warrant investigation, as the protocol seems very interesting to decode! Also, his communicated using simple pulses to ground to change state, when mine use serial communication at around 70kHz for sending actual addressed data to each LED.

720p upload?

If you want some help with a Humphrey feild analyzer I worked on them for 15 years

I remeber that thing- being touted as the latest sh... by my optician- I was rather skeptical at the time.

Geneva drive!

A Geneva mechanism 😍

It's built like it was a high school science fair project!

Thanks for taking it apart, time for the bin =)

The peripheral vision tester…. Doctor turned mine off as at first he thought it was broken. It was working fine.

On the contrary, I think it was a rather interesting teardown in particular because the design was so over complicated and dumb. I would love to see the requirement specification for this monstrosity.

@Smidge204

2 жыл бұрын

Considering how little the electronics actually do, this feels like a very slightly modernized version of something they would have designed and built in the 1950s. Replace the BCD decoders and LEDs with a stacked rotary switch and a bunch of tiny filament bulbs and it's exactly the same machine without the silicon.

@mumiemonstret

2 жыл бұрын

​@@Smidge204 Yes, or they could have placed a second coupled set of the discs with hole in them for the physician to look at. But my biggest question is: Why go through all this trouble to show the patterns to the physician in the first place? Wouldn't it suffice to have them printed in a book for reference or something? And the same goes with the color indicator. Why not just print the name of the colors on the selection wheel? So strange.

@Smidge204

2 жыл бұрын

@@mumiemonstret My thinking is the chart that clips over the display is intended to be written on by the person doing the exam, so perhaps there's a polar graph overlay and the physician circles points the patient sees or doesn't see, creating a map of points over multiple sets of dots. Just a hypothesis on my part, though.

@mumiemonstret

2 жыл бұрын

​@@Smidge204 That makes sense. I still don't understand how the physician could tell which of the dots the patient didn''t see if (s)he told the wrong number.

@plainedgedsaw1694

2 жыл бұрын

@@mumiemonstret thats what that button on handle is for. Youre supposed to click it after seeing a dot. In modern machines it is automated, you just sit on there and click for 10 minutes, while staring at a dot in the middle, if you take your eye off that dot a few times, it turns off and you have to repeat the test. Waiting for this test feels like waiting for a death sentence.

The unit my optician used to use had a single red LED and an X-Y stepper motor arrangement to move it around. Sounded cool when you were being tested! Much better system than this! Of course all this equipment now uses LCD monitors and software, which is pretty boring from an engineering point of view!

Interesting to see amedical electronic device torn down and inner workings showed :)

I guess it was made to be disposed not repaired. Interesting item 2x👍

DFMA… Design For Mike’s Annoyance…?

I mean, "Medical" just means "has the right paperwork", right?

@ZaphodHarkonnen

2 жыл бұрын

It’s a little more complex that that. But there is a lot of documentation for any medical device. Part is to prove it does what you say it does. And the other part is to provide a way to reconstruct how a failure got into a device should something go wrong. This is makes it really irritating to release updates as most any update has to go through the full process even if you’re 100% confident the change will have no impact on the functionality. For my job I’m responsible as a technical lead for a piece of software that’s regulated as a medical device. A lot of the documentation is maddening but the majority of the pain is written in blood. And makes more sense when you think about the intent of the regulations. Also note the regulations are often different in different countries and work is always going on to refine documentation to only cause pain when it’s needed.

Built before the days of Design for Manufacture.

long range gold detector circuit diagram

MMD - Mike Maddening Design

I didn't see that coming!

'eye' would imagine the relationship between the medics and the engineers might have been somewhat detached, since I assume the eye people know exactly what to test for without having the slightest care in how the tests are arranged from an engineering point of view. A bit like the old saying, A Camel is a Racehorse Designed by a Committee

interesting stuff, thanks Mike :)

I don't want the case...but god do I want the electrics and such ....sadly I'm in the usa

Considering the level of both the friendliness towards a service person and that of the quality of certain components and assemblies makes me believe that this is a quick money type of product.

There might not have been much surprising, but it was still pretty interesting.

I guess these days the equivalent machine is made using pretty much just a computer screen?

I had to do a similar test on a much more modern machine after having a stroke before I could get my driving license back. Except on this modern machine it would beep and flash a random spot (or not flash) and I had to press the thumb-button trigger if I saw a dot flash. It went quite quickly as well so you don't have much time to react to a flash and either press (or not press). Good news is I easily passed first time :)

Done this test a lot but its very different today

Hi!

Old circuit traces look like someone literally just drew a line between the components.

@uzaiyaro

2 жыл бұрын

That’s often because they did! Before autorouting, you laid out the PCB by hand.

@mikeselectricstuff

2 жыл бұрын

Er yeah, that's how it was done when CAD was unavailable or too expensive

@uzaiyaro

2 жыл бұрын

@@mikeselectricstuff I would imagine one would also do this for slightly esoteric boards that you aren’t going to make a lot of.

@davidquirk8097

Жыл бұрын

@@uzaiyaro right up until 2008 we were still making one off boards this way, hand drawing tracks with etch resist pens on copper clad board then over to the Ferric Chloride etch followed by cleaning, drying and drilling. I don't miss it at all. It was a lot of work to end up with a functional but scruffy looking board. These days it's straight from schematic to the supplier. Three days later you've got professional quality, fully tested boards in your hand for less than the cost of a pack of PCB drills.

"How many lights do you see ?" from an old Star trek episode, which one ? Happy new year !....cheers.

Its kind of an odd combination of low volume bits (pcb, fibreglass case, components from RS) and all those mass produced injection moulded components in the mechanism. Surely they weren't off-the-shelf parts? Then again, I don't suppose the cost of a short production run of plastic parts was a major consideration considering what they probably charged for it :)

@randacnam7321

2 жыл бұрын

Depending on the plastic used, cheap aluminum molds can be used for short run injection molding.

Hahaha this design is just terrible. The transformer winding just for that bulb is what gets me it's like they didn't apply any critical thinking and did the first thing to come to mind for each and every part.

Interesting, I wonder what the asking price was - a bob or two I should imagine, way way over the top.

"Maybe they did not give a toss"

Neat weird 80's thing! Looks like a medical cheese cutting scale or something. With Geneva drive!

@Lemon_Inspector

2 жыл бұрын

Until I saw another comment mention a "Geneva drive", I thought it was a Gundam reference or something like that.

@wdavem

2 жыл бұрын

@@Lemon_Inspector The Geneva mechanism is a classic device that is also found in the 35mm motion picture projector in every movie theater up until 2012. It drives the pull down sprocket wheel that (intermittently) advances the film through the projector. This may have to do with the origin in Gundam as all professional film runs through a Geneva drive, and very fine good anime has been seen with a Geneva drive!

I wonder if it was rushed to market at the time, could explain the poor quality.

The interesting thing is that it wasn't that interesting 🤔

Surprised you wear a metal watch strap when doing electrical work, I used to wear a watch all the time but even then it was a resin/fabric strap now I never wear a watch.

NO NO NO NO! this "remote control" is not for that. this is what given to patient and patient have to press button when see flash.

@robdavy4468

2 жыл бұрын

Yeh, the patient presses it when they can see a light. As your vision goes, you'll not see certain lights. I'd imagine they flash it with none visible sometimes to make sure they're not just pressing it based on the noise

@bigclivedotcom

2 жыл бұрын

And you quickly worked out that the pop of the strobe meant you were supposed to have seen a dot and press the button.

@MRooodddvvv

2 жыл бұрын

@@bigclivedotcom XD if those who make is wasnt too stupid they would have "all dark" position of that big black rotating disks to catch cheaters

@simonweel7971

2 жыл бұрын

@@robdavy4468 Yes! I have to do this test every couple of years, on a different kind of machine. You look inside a sphere and a spark of light is lit randomly on the inside. And then indeed you have to press the button. But before every spark, the mechanism makes noise before sparking. And as you say, after a few sparks, I found myself clicking at every noise the machine made.....

Gee willikers! There are certainly easier ways to accomplish that these days. I suspect there were also better ways to do it when that thing was made.

Quality medical equipment, right there.

The increasing irritation in your voice as the disassembly progresses is really evident by the end of the video. Definitely not designed to be serviced. Or, alternatively, by the 80s there just weren't good solutions for serviceability.

That's insane hahahahaha

70х

I've always wondered at these optometrist machines. Yes you can find the glitch, but what's the point? In no way you can fix retina deterioration or local aneurysm. Overengineered for nothing.To say more, it's a devices than have as much reason for being as Scientologist's E-meter, albeit more expensive.

@spagamoto

2 жыл бұрын

It's good to know it's happening. People can get into car wrecks etc because they don't know their eyesight is going.

@piceatall6962

2 жыл бұрын

My father used one to track the progression of his brain cancer. The scans matched the spread shown on the MRIs and unfortunately also the progression of his decline.

@yanikkunitsin1466

2 жыл бұрын

@@piceatall6962 that's what I'm talking about. Yes, you can diagnose, but for condition that have no (viable) treatment. Sorry for your loss.

@yanikkunitsin1466

2 жыл бұрын

@@spagamoto you don't need this kind of machine to diagnose bad eyesight

If you're a bozo as an engineer, you go to work in the medical equipment field.

it is called mumbling----muttering....and...also...it is bad manners to talk with mouthful !!!!?