The "short and shake" test totally makes sense. I never heard of that before. Brilliant! Thank you.
@charleslambton78362 жыл бұрын
I'm rebuilding a vintage (1960's) high voltage power supply with a analog meter and unfortunately it came with shattered glass. I wanted to be sure it still functioned before looking at replacing it and your video was right on the money. Thank you for teaching me not just how to test a meter, but also how they work. I'm happy to report the meter is fully functional!
@acestudioscouk-Ace-G0ACE2 жыл бұрын
I found this video at a very apposite time. I have a project and some lovely old meters; now I know how to incorporate them into the project. 73 and thanks.
@stupid-handle Жыл бұрын
Hey w2aew, this video is pure gold! so entertaining to watch!. I wouldn't personally mind a sequel talking about proper use of these as voltmeters, ammeters, and other applications. All the best.
@w2aew Жыл бұрын
I did do a followup on show to design a shunt to use as a higher current ammeter...
@stupid-handle Жыл бұрын
Not being videos from you that have popped up in my recommended list and that I have watched straight away, I'm watching you channel from older to newer videos, so I'll hit it sooner or later. Thanks!
@stevenA442 жыл бұрын
It really surprises me that while looking (last night and this morning) for information on how these meters work, that I was only able to find this video, and it has told me a lot about how these meters work and how to use them. Thank you for making this video. I will save this for future use! Why it didn't show up in a search last night it beyond me. Maybe I used a different search term or something this morning.
@w2aew2 жыл бұрын
Well, I'm glad you found it! I have a followup video that discusses how to calculate the value for a shunt resistor if you want a larger full scale current rating.
@LenPenzo Жыл бұрын
The HP15C at 0:45. Nice. I still have mine after buying it new in 1983. Still works fine. Replaced batteries twice in 40 years.
@W1RMD Жыл бұрын
Thanks for the short and shake test and the link for the meter faces. Also, I like to put diodes going both directions across the meter terminals in case of accidentally putting too much voltage into it. The diodes will limit the voltage to the drop of the diodes. Most meters reach full scale long before the .6 voltage drop in the diodes, but although that much would peg the needled abruptly, the meter would still live through it. Germanium or Schottky diodes could be used for "more" protection. I also use an auto ranging dmm in the ohms setting and the small current from the meter is enough to safely "fs" the meter.
@v1970lima9 ай бұрын
I ask myself why high quality channels have few inscriptions while s#*% ones have millions?!!!! Alan, I wish you a healthy, long and prosperous life, but are you working to keep your legacy alive forever? We need it!!!!!!!!!!!
@StuffWithKirby11 ай бұрын
Excellent video. Explained everything perfectly. I picked up some old tube tester gauges this weekend and was wondering how I could repurpose them. This saves me a lot of time.
@judo-rob51973 жыл бұрын
Wow. You continually amazed with your depth of knowledge, and your clear explanations and demos.
@craignehring8 жыл бұрын
A most helpful video, I especially liked the short & shake part. I've always felt uncomfortable when trying to test these meters, now I know Thanks
@jaredkusner11378 жыл бұрын
Awesome! I tested an old meter I thought bad, Its good! I adjusted it and its back in service. Thank you so much for a great class. Also downloaded meter basic and its great.
@hammershigh8 жыл бұрын
Thanks! As usual, precise, clear and very informative. It's a joy to watch such competence. Best regards
@thats2kewl6 жыл бұрын
A great video. You really cracked me up when you said the meter would be "hosed!!" Totally took me by surprise and had me in stitches!
@Calixj232 жыл бұрын
Excellent video. Very good advice. Now I can reuse a lot of old meters that I thought were of no use. Keep up the great videos.
@dirkbergstrom97512 жыл бұрын
Excellent, thank you! I knew how meters worked but was pondering the best way to simply and properly determine their full scale deflection for exactly the types of applications you discussed. Very nice, professional, succinct... what can I say?! Thanks again.
@jackfiamingo91806 жыл бұрын
THANK YOU! Just bought a 40 piece lot of some excellent vintage meters. I plan to clean and calibrate them, then return them to the market so they live on for another 70 odd years. I really appreciate the info.
@crocellian29727 жыл бұрын
Very useful. I learned this stuff so young that it got fuzzy when the 8000 series CPUs ate the world. Nice to get it back into memory.
@KlondikeMike6 жыл бұрын
Meters, meters, meters everywhere. But did I ever know how they worked or how to test? Nooooo. I do now. Thanks for sharing your knowledge on this topic.
@rickgoebel67248 жыл бұрын
This was quite good. Even after using them for 40 years I have learned something new.
@stuartwelsh83565 жыл бұрын
Thanks Alan. Really enjoying all your videos and have built some of the Sawtooth generators. I just recycled a n old dB meter from a very old (dead) induction loop tester and was able to test it 100uA FS using your instruction. Great stuff.
@shamrock19615 жыл бұрын
This has to be one of best introductory videos I've seen concerning analog meters. I hope you will add to this presentation with how to build a meter for a specific task/project!!! :-)
@w2aew5 жыл бұрын
I have a few videos that discuss applying a meter to a specific task: kzbin.info/www/bejne/aoaQn6uapZJ_etk kzbin.info/www/bejne/bYCveKathpx8eas
@wither88 жыл бұрын
Great video as usual Alan. You , Paul Carlson and Sharhair put out the best content!
@w2aew8 жыл бұрын
Thank you, honored to be in that company!
@jaa939978 жыл бұрын
^ damn right
@jaa939978 жыл бұрын
***** Shahriar from the signal path blog. A most amazing dude
@user-sw7oh9oy6f6 жыл бұрын
Big thnx to you - got my old meter dropped from 300k to 24k and now have a nice DC 24V meter instead of 300V .001A SENSE
@mikesradiorepair8 жыл бұрын
Excellent demonstration of testing meter heads. Your killing me though. I searched for 4 years for the Harrison power supply meter you have there. Purchased 3 of there power supplies and one of them had a broken volt meter. Finally picked up one at a HAM fest several months ago after years of searching. :) One tip on stuck meter movements in really cheap meters used in chicken band radios. The meter movement pivot pin screws have thread lock applied to them and trying to adjust them to loosen a stuck meter movement almost always results in stripped screw heads. A drop or two of GC radio and tv cement solvent quickly disolves it, you can then loosen the screw about 1/4-1/2 turn to free up the movement and then the thread lock dries again so no need to reapply. Mike
@cwgreenley8 жыл бұрын
Great explanation! I was just trying to find this info a few weeks ago and couldn't find anything this clear and concise.
@TheRangerDale8 жыл бұрын
Very Good Alan, Being working in a Meter company for years, analog and digital, We would be Proud To shown this Video to New Hiries . One thing would like to add is even tho the cal point at full scale show correct one thing that might be a problem , is that how it is to be mounted and unit not reading properly. That being cal poise factor, meter laying flat verse meter upright.If you find that there is a Different it can be corrected by repoiseng the unit.on either Tail, or cross arm of its weights .Meters that are made poise is thee Factor in a good meter with its tolerance to Spec. Hints checking Tail poise unit turn at 45* where pointer is Horz and laying on zero, and Cross arm check meter pointer straight up vertical looking at Zero.I did not mean to carry on so just to add to info for those that may have had problems in such, poising movement across the scale. Enjoyed it very much keep them coming Yep thumbs UP in deed, Looking at your Hits Hummmmm great Job . Two Great Shows Here and Mr Carlson labs Boy the knowledge a person can get .. 73's Dale
@w2aew8 жыл бұрын
Good information, thank you.
@Homer195218 жыл бұрын
Recently had a stuck D'Arsonval on a Yaesu I bought. I readjusted the pintle set screw; loose direction first & then just a little past the original setting and that fixed it. Also got a tip to just exercise the meter via a signal generator or nearby strong station. Of course if the meter is out of the rig, then you could do that via a PS. Burden voltage is also a concern on cheap ammeters when checking FS current. But not an issue on your to die for equipment. Nice Vid.
@miguelmejia34252 жыл бұрын
Wonderful and thorough explanation to start working with these meters. Thank you.
@IgnoreMyChan6 жыл бұрын
Absolutely very helpful video! I'm thinking about making a wide analog meter panel (with about 10 analog meters) for on top of my monitor to keep an eye on all sorts of network information in a fancy way. I'll place RGB LED's as backlights so I can highlight the most important events with RED but I love the good old yellowish backlights as default :) Thanks for this great video!
@ate5087 жыл бұрын
Thank you for the nice brush up and handy circuit for testing unknown meters.
@Willam_J7 жыл бұрын
Who would down-vote this video??? It's complete and entirely factual. I didn't notice a single mistake or omission of information. It doesn't drag on and is presented in a concise and enjoyable way. (I can tell you with 100% certainty that these down-voters don't have a better video or any videos at all.)
@w2aew7 жыл бұрын
I seems to get a few down votes in every video. Oh well, can't please everyone.
@Willam_J7 жыл бұрын
Well... I can tell you that your videos are great. I've been an EE for 28 years and I enjoy watching how other engineers approach and solve problems. You have one of the best electronics channels on KZbin. Thanks for all the great videos.
@hank15195 жыл бұрын
Trolls.
@ydonl5 жыл бұрын
I've been looking at that across a lot of presenters; I'm guessing the dislikes are about 0.5% to 2% of the likes, no matter what, at least in the kinds of things I watch. At 10% or so, you figure something went wrong somewhere... maybe a bad production decision, whatever. Then actual content issues go up from there!
@Velkro50005 жыл бұрын
..and ‘At the end of day’ its fun to watch. Mega useful!
@TheRadioShop8 жыл бұрын
Darn YT notifications caused me to miss this one. Great video Alan. Very well done and very informative. Sometimes when I print the scale I turn the existing face over and attach to the back, since the face is mostly the same. On a few rare occasions I have re-wound the coil to get some meters back working but it is a lot of work. And good watch repair techs and replace those springs :) Thanks again for the video.
@howardhall23007 жыл бұрын
Great video as always; I have had a couple of VU meters from an old cassette deck lying about for years. I now know their both 200uA meters! Many thanks.
@w2aew7 жыл бұрын
Glad to help!
@kgsalvage63062 жыл бұрын
You always have a video on something I'm trying to figure out. Very informative video!
@joelhall60688 жыл бұрын
Alan you do great videos,you would be a great teacher
@hadibq2 жыл бұрын
👍 loved the "short and shake" trick 👌
@sand00779 ай бұрын
Clear and concise information, thank you for posting this! If the coil leads are broken, can it be repaired or is it a tosser? 🤔🙂
@bigmac49484 жыл бұрын
Best explanation I found. Have already put to good use. Thanks!
@jeromekerngarcia8 жыл бұрын
Great video Alan as usual. Takes me back to one Spring day in Soph EE lab where we learned about analog meters (essentially the only kind available to us in '74 :-) so we'd understand how and what we were really measuring. I *like* and in some cases *prefer* an analog VOM over a DVM. Don't get me wrong - sometimes I need to know if I'm looking at 2.45 or 2.55 volts, but many times a quick look @ an analog VOM "Yep about 2.5 V," is close enough. Thanks again for a good refresher. Gives me a good topic to discuss when I go melt solder with my nephew ...
@w2aew8 жыл бұрын
+jeromekerngarcia Yes, there are many times where I prefer an analog VOM like my Simpson 260 - especially when adjusting or tuning circuits - much easier to watch a meter movement than to follow digits on a DMM. The segmented bargraphs on many DMMs are a very poor substitute for a real analog meter.
@smash7777-6 жыл бұрын
Awesome video! I never knew anything about analogue meters yet what you just taught had me captivated right through and now I am interested to learn more! Like some of the other posts say "you have a good way of teaching" and put things in laymans terms very well. Thank you for sharing...Oh aye...subscribed too....and you don't need me to tell you what to think of the thumbs downers! NOWT! :)
@keithking19854 жыл бұрын
Terry 01:... If you do learn this stuff I guarantee you that you won't regret it. I started learning electronics last October 'ish and it has changed my life for the better. I'm 40 years old have no kids not married or have a girlfriend. (By choice) and I have to say that this has become an obsession!! And I'm a good way. The amount of learned in such a short time is amazing. An all just from watching videos on KZbin and getting books from the library. Trust me if you haven't already got into it you should, you won't regret it. Plus it's such a cheap hobby to get into. Electronics equipment is so cheap these days and off good quality.. Hope this message gets to ya and you take my advice👍
@keithking19854 жыл бұрын
P.s.I started in October 'ish 2018 and an already building my own circuits. And all it took was a video I seen one day that blew me away like you said in your comment about this video. If you want to know about more good channels for learning id be happy to let you know the ones that I learned the most from. Good bless and good luck👍
@michaelferreira20526 ай бұрын
Excellent job 👏 I really needed this info
4 жыл бұрын
I did this to boost HP in my car, it used to say 12.4v after a few days of sitting outside due to the Corona Virus. After I did the face plate mod, it now reads 14.6v, enough to start my car even with the low battery CCA. I was able to overtake many EG hatchbacks.
@SeAfasia8 жыл бұрын
Thanks for your presentation and tips Alan...
@g1fsh8 жыл бұрын
Thanks Alan there was some really useful information there and very well presented.
@ernestb.237710 ай бұрын
Hi Alan. I recently acquired an Metrawatt MA4E analogue meter, but one with active circuitry (op-amp to create voltage-to-current circuit), with a nice 10MOhm input impedance on DC. I realized that the meter is non-linear, to the proportion that is out of specification of +/-1.5% I suppose that would be of the reading, but have to admit I have not checked the user manual on that point. I have tried adjusting the gain and offset, but could not get it right over the whole scale. The deviation is just to big for my taste. So I have looked in a lot of parts of the electronics, but at last I tested the meter movement itself, to realize that the problem is there. The meter is not linear. It is a 30uA classic d'Arsonval movement. When looking at 0-100 scale, when on 10 it needs 2.8uA and on 100 it needs almost 32uA. The values in between roughly follow the function y=5*ln(x)+76.6 So the scale is like compressed. I don't have much experience with galvanometers and am very curious to solve this puzzle. One more gentleman that also acquired the same type multimeter with similar serial number noticed the same problem, so we are emailing back and forth with our individual findings. First we thought it is something in the circuitry and the op-amp, but now it is clear which part of the meter is responsible for the deviation. Could it be the Hook's law, non-homogeneity of the magnet or... and how to fix this issue? Glad to hear your opinion.
@CraigHollabaugh7 жыл бұрын
Thanks for the tip on opening in a clean environment.
@felixcat43468 жыл бұрын
Nice presentation, the big meter at the opening with the rise and fall is a Scientology E-meter. It is used to fleece people of their money. My apologies to Tom Cruise and John Travolta.
@SarahWattCA8 жыл бұрын
+Joseph Nicholas lol good catch. I've heard of those but I've never seen one before.
@SarahWattCA8 жыл бұрын
***** "* is worse" has never been a good argument in favour of something
@SarahWattCA8 жыл бұрын
Sorry, I thought that was a defense of Scientology.
@robertcalkjr.83258 жыл бұрын
+Rascal's Fx Evolution is the most ignorant. And Christians aren't the ones murdering people.
@jackfiamingo91806 жыл бұрын
I am embarrassed to admit that I also recognized the E-Meter. I worked one of those for over two years when I was a gullible young man. I am happy to report that I am no worse for the wear. ;)
@alphahr6 жыл бұрын
The best explanation I've seen so far
@ziggyinc2 жыл бұрын
I'm working on a Drake MN7 and the meter was not working. This video helped me troubleshoot the meter! Thanks so much.
@philspargo95438 жыл бұрын
Excellent video, easy to understand, well planned ! Thanks Alan ! How about a video calculating current shunts ?
@w2aew8 жыл бұрын
+Phil Spargo I'll add that to my list.
@bityard8 жыл бұрын
Very helpful video. And timely, as well. I've been watching fleabay for vintage 0-15 V DC to use in a power supply I'm building but there aren't many to choose from. There are a whole bunch with other voltage ranges and I was wondering if they could be modified for my use. Thanks to your video, I know they can!
@w2aew8 жыл бұрын
+bityard Most likely - and those that have a particular voltage rating on them would probably need a series resistor to make it read correctly anyway (most don't have the resistor built in), so just get one that has the style you like, and make it read what you want.
@dandearman28713 жыл бұрын
I used to work on a lot of pyrometers and hi-pot testers with meters and found if you pull off a plastic meter face, do not clean it if you don't have to. I've cleaned plastic meter faces and had them develop a static charge that pulls on the pointer and can makes it stick to the meter face. A anti-static cleaner may fix this problem but I've never tried it.
@cliffjones78685 жыл бұрын
I would add a couple points. The springs serve a double purpose. #1. It is the electrical pathway to the coil itself. #2 as was stated It helps to keep the pointer stable,
@30mAkills Жыл бұрын
good, great, important point which the uploader skipped. Material is phosphor bronze which is a good conducting spring material. Steel is bad conductor and also corrodes during monsoon. Kishore kumar from Chennai, India.
@EI6DP2 ай бұрын
Really great video.
@gilbus49897 жыл бұрын
Very educational and informative? Reminded me of the basics I learned in college.
@gordslater8 жыл бұрын
Many, many moons ago, a class of polite and studious trainee radio officers were studying a Bander-copied handouts in an introductory class on meters and movements. When the class finished, one student gathered his study books, notes and papers, then loudly kissed his handout with an exaggerated "mmwah!!!" Looking very puzzled, the entire class and lecturer stared at the student with eyes wide.. After a few seconds of silence and amazement, the trainee asked "would anyone else like to kiss my D' Arsonval?"
@TheHellfiremissile4 жыл бұрын
Thank you. I've gained a few old meters and I now know how to test such. This old dog can learn new tricks. Hi Hi.
@bucheronix4 жыл бұрын
This type of galvanometer was invented by Jacques-Arsène d'Arsonval. en.wikipedia.org/wiki/Jacques-Ars%C3%A8ne_d%27Arsonval His name is pronounced "darsonval", in one word. It means "from Arsonval", a village in France.
@fullwaverecked4 жыл бұрын
The fog is clearing. Great video!
@karlfell37688 жыл бұрын
Fantastic video as always Alan, keep up the great work. Karl
@robertcalkjr.83258 жыл бұрын
Thanks for the tips Alan.
@balanbogdan91602 жыл бұрын
This was very useful, thank you!
@miked44028 жыл бұрын
I enjoy your channel quite a bit alan, a lot of knowledge !
@PapasDino8 жыл бұрын
Me too, into the supply closet to pull out all the old meters so they'll be marked properly, there goes the weekend! ;-) 73 - Dino KL0S
@joepereira34218 жыл бұрын
Thanks Alan, as always very well presented.
@maurosobreira86957 жыл бұрын
Alan, thanks for the excellent video!
@MitchullMoroz-it7ui7 ай бұрын
Hi, I like your video! My question is how to use a new style vehicle speedometer (that sweep tests with computer) in a analog circuit like a cb radio watt meter? Thank you!
@hahaagi4 жыл бұрын
Om 님 잘 보고있습니다. 감사합니다. 73
@keithking19854 жыл бұрын
That ampmeter was reading 200 mili amp on the first reading not 200 micro amp. I'm sure you meant to say mili amp and not micro. That was really cool tips👍 very good video😁
@w2aew4 жыл бұрын
It was actually 0.200mA, which is 200 micro amps.
@keithking19854 жыл бұрын
@@w2aew Oh sorry I didn't notice the "0."which obviously makes it micro... anyway very cool video i learned some very handy tips.
@waynegram8907 Жыл бұрын
The DVM meter is only testing the transistors and Diodes under the DVM meters Low Load. Any reasons why the DVM meter is a "Low Load" and not at a High Load when testing transistors, FETS, diodes?
@billwilliams63385 жыл бұрын
how do you troubleshoot equipment that uses those analog panel meters, how do you know if they are good or bad because using a Fluke 87 DVM meter on ohms mode they will measure 10 ohms across the analog panel meters so I don't know how to tell if its good or bad. Older equipment in the 60's and 70's used those analog panel meters to measure voltage, current, wattage, etc. But when measure the ohms across the analog panel meter when using my fluke 87 DVM meter it will measure very low resistance. When an analog panel meter is to measure a voltage what is the difference between an analog panel meter to measure wattage or current its the same thing the analog panel meter is either in series or in parallel. I'm not sure if the analog panel meter is internally different to measure voltage, current, wattage, power, etc.
@miker837911 ай бұрын
Have you ever compared a Cb type modulation meter to a scope? And also wondering how those modulation meters work. Possibly the increase in voltage from the unmodulated signal. Wonder if 100% is actually 4x.
@w2aew11 ай бұрын
I haven't look at the CB modulation meters to see how they're setup/
@MrDeathray1178 жыл бұрын
your microphone sounds fantastic!
@w2aew8 жыл бұрын
Thanks, it is just the built in mic on the camera.
@ghlscitel67142 жыл бұрын
Still interesting though this subject was important to me between 1960 and maybe 1970. I even was tinkering one from scratch in that time when I was a very poor pupil.
@bigfoottoo28416 жыл бұрын
Really good hand drawn meter.
@totallysmooth12033 жыл бұрын
My problem on a Weston model 685 is that the meter movement is actually burned out or open. So this testing procedure won't work. And there is no FS printed on it. How do you find the full scale value in an instance like that?
@billwilliams63385 жыл бұрын
How do you test panel meters if they are good or bad because when you measure the ohms of a panel meter it measures very low ohms like 10 ohms so I don't know if the panel meter is good or bad. If a panel meter measures watts how is the panel meter connect to the circuit in series or in parallel? If the panel meter is bad not working can I connect my fluke DVM meter across it in parallel to act like a current or wattage panel meter?
@alexrobi1000 Жыл бұрын
Great video! I was wondering if those meters can be calibrated or is the only adjustment available is the zeroing of the meter? Thanks
@w2aew Жыл бұрын
Some have adjustments, but many don't. But a talented meter tech can manipulate the spring to change the full scale.
@phasorsystems68734 жыл бұрын
Ohm my gosh you should try this application! Browse for androidcircuitsolver on google
@berniken65118 жыл бұрын
Good video Alan, good info and tips....................Berni
@paulspencer1535 ай бұрын
Great video. My trusty Multi Meter has gone open circuit on the coil. Its 18 microamp FSD. Can you do the opposite eg. Make a 100microamp FSD read FS with 18 microamps instead of the reverse with a shunt. Its just I cannot find a 4.5inch 18 microamp FS meter
@w2aew5 ай бұрын
Unfortunately, no, you can't make a meter movement more sensitive.
@waynegram8907 Жыл бұрын
I was wondering how to measure the inrush current of a power transformer or just transformers in general because when you the EMF of the collapsing and expanding is what determines the the inrush current of the transformer guitar amplifiers have a power transformer and I don't know how to only test the enrich current of the power transformer with the circuit still connected would you have to disconnect the circuit and order to measure the the enrich current of the power transformer the AC power transformer and the thing is is the two rectifier to isolate each components in Rush current how can you do that because the circuit is connected or would you have to disconnect it to know how much the power transformers in Rush current is and how much is the tube rectifier what is that in Rush current. Trying to isolate the enrich current per each component the filter caps the tube rectifier and the the power transformer the problem is how to isolate each component in Rush current cuz each one will generate a different in Rush current but it's hard to do this in circuit to try to measure the inrush current it's a isolate each component while they're connected in circuit
@philipacovington2 жыл бұрын
@12:33 L Ron Hubbard would be proud
@hamimbhatti92762 жыл бұрын
Can you help me please to use Victor KD-A6 vu meter I want to use it in other my local amplifier
@KL3NCH Жыл бұрын
Excellent Sir! Vy tnx.
@iamhe9992 жыл бұрын
it would be nice if you went a bit further and measured the (mv full scale) and calculate the (internal series resistance) along with (ua fullscale)... these 3 numbers make calculating series and shunt resistance very easy to get other ranges..
@w2aew2 жыл бұрын
I do this in the next video in the series, where I show how to design a shunt: kzbin.info/www/bejne/aoaQn6uapZJ_etk
@markd.nightingale42664 жыл бұрын
Very informative! Thank you very much sir!!
@jonathanhendry9759 Жыл бұрын
Nice e-Meter meter.😀
@Kurt1968 Жыл бұрын
Another great video, Alan, thanks. Question - I have a Weston Model 901 DC Ammeter and at the bottom it states to use it with an external 50 MV shunt. Can you explain the units of this shunt? Wouldn't this be a shunt resistor? I think also have the shunt somewhere but need to dig it up. The ammeter has two scales 0-15 and 0-150 with no switches anywhere. I presume I would need to use two different shunts differing by a factor of 10 ohms?
@w2aew Жыл бұрын
A "50mV Shunt" is a low value resistor that will have a 50mV drop across it at the rated current. It is designed to work with meters that will have 50mV drop across the terminals when operated at full scale deflection. Since the meter's coil resistance will be significantly higher that the shunt resistance, the parallel combination will still be very close to the just the shunt resistance. Thus, it is easier to specify the shunt for the voltage developed at the rated current. For example a 50mV shunt for 10A will be 5mOhms. Yes, you'd need different shunts to use both scales.
@Kurt1968 Жыл бұрын
@@w2aew Ok, that makes sense. So the shunt acts as sort of a current limiting bypass for the meter. The coil resistance is just under 50 Ohms, so with a 50mV shunt, the internals are seeing only a 1mA. I opened it up and the wiring is around 30ga, so its pretty delicate yet the terminals are pretty big to minimize any resistance in the connections. So for the 150A scale the shunt must be pretty big to bring the resistance down to 50mV/150 = .33mOhm. And the wires to and from the shunt and meter would need have very good and clean connections. I don't even have a meter that can measure such a low resistance.
@w2aew Жыл бұрын
@@Kurt1968 Correct. Measuring resistance that low definitely requires some special equipment, 4-wire sensing, etc. For these high-current shunts, the resistance is so low they typically spec'd them by their voltage drop at rated current. To learn more about current shunts and how they change the scale on a meter, see this video: kzbin.info/www/bejne/aoaQn6uapZJ_etk
@jonnyrocket89544 жыл бұрын
great presentation, thank you!
@waynegram8907 Жыл бұрын
It would be nice if you made a video lesson on thinking of applications when you would want to use an analog meter and digital meter for "fast response times" Fast events. Example when measuring old 40's and 50's transmitters/receivers would be to measure the power supply voltage when receiver and when when keying the transmitter because the voltages will change very fast when measuring from receiver to keying the transmitter and most DVM meters aren't fast enough to capture the events. I have even tried using the Oscope External trigger port to try to record the very fast events but also the Digital Oscope are slow. I'm not sure what in the Oscope Specs to look for to be called "response time" or how to get a faster response time out of an Oscope. I'm sure you have a lot of examples to make a video lesson to know when to use a DVM meter or Oscope to measure very fast events and response times.
@w2aew Жыл бұрын
Analog meters don't respond very fast either (due to mechanical intertia). An oscilloscope is the CORRECT tool to use to capture transients. Digital scopes are exceptionally good at this. You don't need to use an external trigger, you can trigger on the transient itself. Response time of the scope (how fast a transient it can capture) is related to the scope's BW and sample rate.
@waynegram8907 Жыл бұрын
@@w2aew How do you compute/calculate the Oscope Response time based on the BW and Sample rate? is there a formula. Can you give a bunch of examples of when measuring fast response times in various applications and circuits.
@w2aew Жыл бұрын
@@waynegram8907 Scope risetime can roughly be approximated from scope bandwidth as risetime=0.35/bandwidth. So a 50MHz scope will have a risetime of about 7ns.
@waynegram8907 Жыл бұрын
@@w2aew 0.35/50Mhz = 7nS , but is it always 0.35/scope bandwidth?
@w2aew Жыл бұрын
@@waynegram8907 Yes, this is a good rule of thumb to estimate the scope's inherent risetime.
@SomeGuyInSandy4 жыл бұрын
Excellent video! Thanks :)
@MLX14014 жыл бұрын
Great video & very handsome clamp board :-)
@lalogarcia66862 жыл бұрын
great video!!
@tubeDude482 жыл бұрын
Allan, the above software link is wrong. Your missing the "2".
@w2aew2 жыл бұрын
Thanks, I'll fix it...
@bobslagle65223 жыл бұрын
I liked your video. I have a 0 - 10 Amp analog meter, and a 0 - 15 volt analog meter. I tested the voltmeter and the needle wanted to move backwards when in reverse. Could I adjust to have 0 centered at the top? I would like to use these meters on my HO train layout.
@w2aew3 жыл бұрын
There are meters designed for a center-zero.
@ourkid20009 ай бұрын
Great video! I have an ammeter out of a classic car that only has charge / discharge markings (needle in the center when off - 12V system) that I would like to test. It uses a shunt wire, that cannot be removed from the car, in parallel with the meter. I guess the resistance of the shunt would be too small to measure accurately with a DMM. I would guess that a very small proportion of the charging current would be passing through the meter itself. So, I have it on the bench currently and I'd like to test it out to see how much current would actually give full deflection. Would a 10k ohm resistor be of use for this test? I'm thinking I'd have to use a lower value resistor than you would be using here? Do I even have to use a resistor? I have a bench power supply as well.
@w2aew9 ай бұрын
You can certainly start with the 10k resistor in series with the meter. Start your power supply at 0V and slowly start bringing it up while watching the meter. If you get to your supply's maximum voltage and the meter still hasn't reached full scale, then start over with a lower value resistor, etc.
@ourkid20009 ай бұрын
@@w2aew Wow thanks for the quick reply! Ok, will try that thanks! I had the ammeter hooked up, with a little incandescent test lamp for a load, like this a couple days ago just to see if it was working: PSU (+) ---Small Lamp---(+)Amm-Amm(-) ----PSU (-) I had the power supply dialed up to 11V, the lamp was brightly lit and the PSU display was indicating that it was outputting 280 mA. The ammeter was showing just a little bit to the "discharge" side. Maybe 3 or 4 needle widths. Does this sound like things are functioning correctly?
@w2aew9 ай бұрын
@@ourkid2000 Yes, it sounds like this is a fair high current full scale meter, considering that 280mA only moves it a small amount.
@joostjepek4 жыл бұрын
Hi there, liked your video and efforts to explain. I've checked the website, the address link is invalid, but if you choose the main domain address, you're fine, or just use the aforementioned address but leave the 2 out that'll work .. cheers
@edwardpedlar39858 жыл бұрын
Great Video I think there are two different kinds of analog meters, Type 1 shows the needle proportional to the current (I) Type 2 shows the needle movement proportional to the square of the current (I^2) Yours seem to be all only linear, right? How do you know you have a meter that reacts to I^2?