#191

Рет қаралды 32,632

9 жыл бұрын

In the previous video, #190: Transistor Current Sources (link below), I made an error in my measurements because I ignored the loading effects of one of the meters. Since every mistake is really an opportunity to learn - hopefully you'll learn from my mistake! Even though there were two subtle clues that this error was there, I ignored them - shame on me!
The Simpson 260 VOM has a sensitivity of 20,000 ohms/volt. I had the meter in the 10V range, so it had an input impedance of just 200kohms, and this was in parallel with the current source. Therefore, my calculated output impedance of 190k was really dominated by the VOM, and the actual output impedance was much larger.
I apologize for the error, but hopefully there is a lesson here for you. Here is the link to the previous video - a tutorial on Transistor Current Sources:
• #190: Back to Basics: ...

Пікірлер: 144

@Ogma3bandcamp 9 жыл бұрын

This video is testament as to why this guy is the best electronics tutor out there.

@emcgon 9 жыл бұрын

I think both videos are great. If there hadn't been a mistake in the first video, we wouldn't have had this one, and this video stands alone as useful and interesting. So personally I'm glad for the mistake in the first one. I'm absolutely loving your "back to basics" series...I hope there are lots more of them to come. Thanks.

@jW-xz7sr 5 жыл бұрын

Wow, wish more people in the world thought this way. Most folks don’t own up to error. Learning from mistakes and teaching others is noble.

@robertcalkjr.8325 9 жыл бұрын

Good man Alan. Not many people own up to mistakes. Thanks.

@nnamrehck 5 ай бұрын

I am a retired research chemist. When my kids asked what I did, I told them my job was to make mistakes and learn from them.

@EJEuth 2 жыл бұрын

Excellent demonstration - and that comment to register the FUNNY findings is a great advice. Thanks for sharing!

@davecc0000 9 жыл бұрын

Good on ya Alan! In some ways the 2-part "oops" incident is better than a "no-oops" one. It makes us look at #190 and see what we missed, too. Most of us, anyway... Cheers.

@davecc0000 9 жыл бұрын

Although I did have the thought that "constant" must be a euphemism, after seeing the variation in I with the change in V. (c;

@w2aew 9 жыл бұрын

davecc0000 It is certainly clear that the majority of the variation in current measured was the current going through the VOM - so the constant current source is much closer to being constant with respect to load voltage than was originally shown in the first video.

@mjlorton 9 жыл бұрын

Always valuable lessons from you Alan. Thanks for all your valuable guidance and input with my journey down this path. Cheers, Martin.

@w2aew 9 жыл бұрын

Thanks Martin!

@BMRStudio 9 жыл бұрын

Thumbs up! Best teacher who share his own mistake! I just watched yesternday the current source video, and I get a bit smile when I see the old voltmeter without high impadance tube or FET driving. Now I'am sure more about Myself :) But, nice to see the correction! Thx!

@danlscan Жыл бұрын

I know this video is 8 years old but I was just poking around an opamp circuit and noticed my supply current fluctuating as I probed with an 8050A DMM. I then used a Heathkit V-6 VTVM to see if the perturbations diminished and they did. I now don't feel so bad for the amount of time I spent refurbishing that thing. This series is great and I continue to learn a lot from you. Thanks! I used a Simpson 260 for checking DC motor health many years ago. The 260 worked OK for that. I'd say if you get a significant measurement and account for the input impedance then all will be OK but I could be wrong as my experience lies elsewhere. Again, many thanks.

@roastbeef82 9 жыл бұрын

This is a subject in itself that I am studying at the moment in preparation for my Ham radio licence here in France, so yet again, a great video. I wonder if future exams will continue have this subject in its syllabus. And don't forget, someone who never made an error never made anything!! and you certainly make some great video's. Thank You Phil.

@kb7skb 9 жыл бұрын

Alan, I just want to say thanks for all of your wonderful videos. Don't worry about the mistake. Anyone that has worked with any kind of electronics has made this type of error and will continue to do so. It's part of being human. Thanks again!

@gregorymccoy6797 3 жыл бұрын

Now this is a great video on so many levels. Well done, Sir.

@jonsanford0 9 жыл бұрын

The more you learn the more you have to forget

@CH_Pechiar 9 жыл бұрын

This video makes you stand as a more professional content producer, good! BTW, when I saw your last video it was late at nigh and I went to bed more confused than before, so thank you for the follow up.

@KD0CAC 9 жыл бұрын

I do a tech net here and I always say a learn more from my mistakes , vs when everything is going well . Thanks for more learning ;)

@rrangana11 9 жыл бұрын

Very good Video demonstration of the statement “The act of measuring with instruments, alter the state of what they measure in some manner”.

@larryrenaud7462 9 жыл бұрын

Hi Alan it takes a strong man to own up to his mistakes. I have found your videos very informative and look forward to when new ones come out. I always learn something, even when you have to redo one due to errors, we take things for granted or in my case as we get older we tend to forget. GREAT JOB!!!!

@Ghost572 5 жыл бұрын

Why does it take a strong man to own up to his mistakes lol?

@jonahansen 3 жыл бұрын

This is great! A hands on, real world analysis of events that really happen to people when they are troubleshooting circuits.

@mikeduino4596 9 жыл бұрын

I enjoyed this, as I also like analog meters. 20+ years ago in tech school, meter loading was a topic that was given significant coverage by my instructors. I love my 260, and also my 374 uammeter. I just have to keep in mind how and where to use them. thanks again for your work in these vids!

@FronbondiSkegs 9 жыл бұрын

Just found your channel, but I'm really enjoying your videos. Thanks for taking the time to make them.

@N.A._McBee 3 жыл бұрын

A still valuable video even after these years 😉 ❣️ Thanks for sharing this experience!

@richsmith46 7 жыл бұрын

If it makes you feel any better I've done the same thing myself, I also grew up with moving coil meters. It's very easily done, none-the-less I'm sure that many people learn lots of new things by watching your videos. For me it's a brave man who sees, acknowledges and corrects (even very minor) mistakes. I have nothing but absolute respect for that. Keep the videos coming!

@alanwolke6253 7 жыл бұрын

Thanks for the nice comment.

@pentachronic 7 жыл бұрын

I have to say that admitting your mistakes is part of the scientific process. One can only move on when you admit and learn from your mistakes. One of my friends used to say that an 'experienced' person is one who's made a lot of mistakes and learned from them. So listen to the experienced person to avoid making the same mistakes they did !!!

@desnort 9 жыл бұрын

I really like your videos. You are an excellent teacher, and, after all, we're all human. At my age, I forgot what I did yesterday (oh yeah.. went to a Hamfest :-)) ... What you did here was turn a common error into another opportunity to excel as an instructor. Heck, we all make mistakes... best to learn ( or be reminded ) from them... and you took it a big step further and shared. BIG thumbs up, sir!

@tubeDude48 4 жыл бұрын

Bob Pease was a wonderful guy! I miss him.

@famossfla 9 жыл бұрын

Thanks for the update. I wish our politicians would own up to their mistakes as well as you do. Thanks for sharing.

@researchandbuild1751 5 жыл бұрын

Thank you for the follow up video. It helps me understand electronics much better even to see mistakes others make since i make so many myself. Good learning material

@w2aew 5 жыл бұрын

Yes, you definitely learn more from your mistakes then you do from your successes.

@WPF465B Жыл бұрын

Great practical measurement video, thanks.

@davidlisney2059 9 жыл бұрын

As always a fascinating video, of course sometimes it is surprising quite how high the impedance of a moving coil meter can be on a high voltage range... even higher than the 10 Megohms or so of a Fluke.

@christophschuermann6512 6 жыл бұрын

Very helpful video to avoid errors in making measurements. You can improve an analog instrument by using an good opamp to drive the meter.

@adriaanroeleveld5823 6 жыл бұрын

Thanks for sharing. In most cases it doesn't really matter, therefore you forget when it does matter!

@Sjampster 9 жыл бұрын

I am glad to learn that ignoring funnyness is something more people do. Great videos again, thanks!

@MrMagnetrixx 5 жыл бұрын

Very nice! And completely true: Note when funny things happen, they probably mean something. Thank you for all your efforts to make your nice and educative videos, Alan!

@pentachronic 7 жыл бұрын

Great videos. Love watching them.

@matematicapraque546 2 жыл бұрын

Always excellent content videos. Congrats and thanks for sharing!

@samba3403 9 жыл бұрын

Grate video, Glad to see you do follow up videos when you over look things, It happens to us all.

@uvatham 2 жыл бұрын

I learnt lot from your channel, Thank you very much

@gadget73 9 жыл бұрын

I work on a lot of old gear, and the schematics with voltage markings always spell out what sort of meter they used. Often its a VTVM for DC, and a 1000 ohm per volt AC meter. VTVM's have input impedance comparable to a DMM so that works out. It does tend to lead to higher AC readings, though considering we're talking about heater supplies, there is plenty enough current that even a 1k meter wouldn't load it down enough to affect anything.

@michaelriner121 5 жыл бұрын

Great Video 👍🏻

@markbell9742 9 жыл бұрын

Hi Alan: Elegant mea culpa. When I have 'put my foot in it' and then tried to brush it off I end-up look foolish and arrogant. Although, sometimes not comfortable, don't lose the ability to be embarrassed. I think it serves use well as you have exemplified. Cheers, Mark ****************************

@indigoskywalker 6 жыл бұрын

Another great vid alan, you sound very embarrassed 😊 I wouldn't worry, we love watching your excellent videos and you really know your stuff!

@opablo_gm 9 жыл бұрын

greeeeeat one Alan... I learned a lot from this one because I am from the generation of kids spoiled by the 10Mohm digital meters :)

@richardgoebel226 7 жыл бұрын

A maintenance person was using a Fluke DMM to check for A.C. voltage on an outlet. The readings were jumping up and down sometimes as high as 87 VAC. I connected my Triplett 630 to the circuit and it showed nothing. His assumption was that the meters were defective. Until i explained about input impedance and loading as well as EMI. The wires were in the same conduit as large wires used for heavy machinery which was turning off & on. Good to know both meters.

@tonybell1597 9 жыл бұрын

Thanks Alan, cracking good reminder, someone once said to me.... On,y God is perfect...... I am reminded of that..... Constantly in my own work! Keep up your great work......

@tinkeringwithelectronics 3 жыл бұрын

Good stuff. Thanks

@James1toknow 9 жыл бұрын

Nice and nothing ever wrong with being wrong.. learned the loading effect in college.. Nice over view.

@iw0hex 9 жыл бұрын

Thanks Alan.. Best regards!!

@jeremyo1457 7 жыл бұрын

really great video and explanation! thank you )))))

@bart99gt 3 жыл бұрын

Saw it first hand when I was adjusting the calibration on my Simpson 260 last night. I had a 1mA current through a resistor and my Fluke 87V as my reference, I put the 260 in series with this setup and saw a small drop in current on the Fluke.

@w2aew 3 жыл бұрын

What you saw was the affect of the burden voltage on current, because you were using a resistor to set the current and not using a current source. All ammeters have a burden voltage - a voltage drop that is inserted in the circuit when the meter is placed in series. Calibration on the 260 is generally done on the 50uA scale where you adjust the trimmer in parallel with the meter movement. Then, after you have 50uA full scale reading, adjust the series pot to get 250mV drop (burden voltage) at 50uA test current.

@spiderjuice9874 7 жыл бұрын

Your videos are excellent and have been a major factor in me starting to "teach myself" basic electronics (hmm, most of the teaching comes from you actually - credit where it's due!). I've acquired a nice CRO and love your 'Back to Basics' type intructional videos. I have 2 novice questions for you: 1) Under what circumstances would using a meter like the Simpson 260 be preferable to using a digital multimeter? 2) Is there a reference book (like an encyclopedia) with lots of circuits where they can be searched via the use you require of them, with details such as you give in your videos (ie. how to use them, variations, etc)? I come from a research background so discovering blunders and owning up to them is not new for me: it adds to you credibility that you can own up to yours.

@w2aew 7 жыл бұрын

1) I use an analog meter like the Simpson 260 whenever I am working on something that I am adjusting or tuning, where it is important to see the "change" in a voltage or current (such as peaking or dipping a response). It's much easier to see this on an analog meter than a DMM. 2) I don't know of a circuit encyclopedia per se. There is a book called Op Amp Cookbook by Walt Jung which is probably the closest thing you'll find. Another great book is The Art of Electronics by Horowitz & Hill. It has a lot of circuit examples, and even has a section at the end of some of the chapters called "Bad Circuits", where you are responsible to figure out why they're bad.

@spiderjuice9874 7 жыл бұрын

Hey, thanks for your quick response - I appreciate it! I will look into acquiring an analogue meter (I have a cheap one somewhere but from memory it's in pieces) and I will definitely try to locate those books. I have a rare day off today so I'll try to replicate a circuit or two of yours to get me started. Thanks again!

@BruceNitroxpro 5 жыл бұрын

@@spiderjuice9874 , Read up on metrology... more than "what it is." How to use standards and owning a few to begin with sure helps put you "into the game." de KQ2E

@billmoran3812 6 жыл бұрын

We all make these simple errors. As engineers, we tend to think of test equipment as "perfect" but, in reality they are not. Good video that illustrated the reality vs theoretical.

@OrbiterElectronics 9 жыл бұрын

Good reminders Alan. Don't worry though mate..Always remember.. The person who doesn't make mistakes hasn't been born yet, and unlikely ever will be :)

@DeeegerD 8 жыл бұрын

+orbiter8 (John) He was born over 2000 years ago but he'll be back :)

@kissingfrogs 6 жыл бұрын

Coming from the previous, I was never going to pick the error. But I have ignored *funny* before, explaining it away as something it was not which dramatically increased time to a solution. Now I try to always remind myself to pay attention and investigate odd.

@SuperRotter 7 жыл бұрын

Hi, your videos and your skill at explaining things is outstanding. In the case of the problem of the voltmeter impedance influencing the measurement, couldn't you simply measure voltage on the other end of the ampmeter? Then only the burden voltage of the ampmeter would contribute, but much less most propably. Thank you.

@1pcfred 9 жыл бұрын

The Observer effect strikes again!

@BruceNitroxpro 5 жыл бұрын

Just bought the book to which you refer! Superb suggestion. We think you rock. de KQ2E

@jasonbrambach6957 8 жыл бұрын

I am new to electronics and I am delving into it from many angles: books (old and modern), radio shack kits with Platt books, Make Magazine projects, radio kits, local arrl group, etc. One thing that I have noticed is that there has been exponential change over the last decade. 1) What direction would you take today in pursuing a career in electronics with the changes in software/hardware? 2) is detailed work on old style circuit with transistors still very useful/relevant? I enjoy the knowledge and the application. Am I on a path of pure hobby as one man told me by spending time on "old school" components?

@w2aew 8 жыл бұрын

+Jason Brambach I think that spending time at the discrete component level gives you a great deal of practical knowledge that is very valuable - something you wouldn't get by jumping in at the Arduino and other *kit* level of things. There is value in both, so don't feel that you're wasting your time on transistors - it is all time well spent.

@SomeGuyInSandy 4 жыл бұрын

No egg. It was valuable news to me. Thanks!

@urlkrueger 9 жыл бұрын

Ahhhh! So Alan really is a human. Or was the oversight the result of incomplete program specifications? Always waiting for your next clip. May you never lose interest in doing these. Many thanks.

@w2aew 9 жыл бұрын

The positive feedback, "likes" and thumbs up that I receive from viewers like you, and the continued growth of the number of subscribers, are the things that keep me motivated to do more! So, thank you!

@jordan390a 4 жыл бұрын

10k-20kohms/volt was and is typical for passive analog multimeters....FET input multimeters really helped true-up your measurements back in the day....I have a vintage Micronta (Radio Shack) analog FET meter that I will never get rid of, even with digital high impedance mms...

@w2aew 4 жыл бұрын

Still a lot of value in having a moving needle...

@jordan390a 4 жыл бұрын

Yes, and there always will be, especially for adjustments for peaks and valleys....

@valebabis 3 жыл бұрын

fine job O.M.

@kjn4685 9 жыл бұрын

We all make mistakes,also a good video I learned a lot

@byronwatkins2565 3 жыл бұрын

The Simpson would have worked fine as the ammeter since its 500 Ohm resistance is negligible compared to the MOhms of the current source. Also, it would be instructive to show the math of how the current source resistance in parallel with the known voltmeter resistance yields the measured resistance; then 1/R_cs = 1/R_measured - 1/R_meter allows us to get a correct current source resistance anyway. The 193k then becomes 5.5 MOhm when the 200k meter resistance is considered.

@aircooledcamper 9 жыл бұрын

There are two kinds of electronics hobbyists or professionals: Those that have made this error, and those who will. I wouldn't be without my analog meters though; they are way too handy for peak and null (among other things). Some of my analogs are high Z (VTVMs or FET), but most are 20K ohms/volt.

@MrWasim100100 3 жыл бұрын

your videos are awesome ... some circuit fun video please on increasing input impedance of analog volt meters by means of transistor emitter follower or some op amp would be nice to compete the DMMs! a vtvm is hard to find for me :)

@w2aew 3 жыл бұрын

An op amp based unity gain follower would be best. An emitter follower would have a DC offset.

@dennisqwertyuiop 9 жыл бұрын

We all make errors thanks for great video

@billwilliams6338 5 жыл бұрын

yes the leads are acting as antenna picking up the signals but the Fluke meters must have a low pass filter build in because it stays close to zero voltage compared to other meters they randomly fluctuate in the normal voltage range. I thought this was a better way of measuring an open circuit because zero volts you can't tell if you have a ghost voltage or an open circuit because its zero volts.

@fmashockie 8 ай бұрын

I just subscribed to your channel and really appreciate your content. I had a question about older meters. I was working on a Tektronix 576 doing some performance checks and in the service manual, they talk of using a voltmeter with input impedence > 500Mohms! Our DMMs today typically have ~10Mohms (depending on range setting). Do you know what kind of meter they were referring to in this service manual? Sorry I know this is a bit of an obscure question, but your thoughts on older meters like the Simpson 260 (I have one as well) having lower impedence triggered this thought. This Tek 576 manual was clearly written in the late 70s so they must have been using an older meter as well.

@w2aew 8 ай бұрын

They were likely using a VTVM (vacuum tube voltmeter).

@GaRbAllZ 9 жыл бұрын

What is the voltage burden on the fluke when measuring current that low? Need to hit Dave up for one of his MicroCurrents :) Great Job Allen

@w2aew 9 жыл бұрын

It was actually only about 4mV, so pretty insignificant. Thus, simply moving the 260 VOM positive lead to the other side of the fluke ammeter would've alleviated the problem.

@power-max 9 жыл бұрын

0:19: Let me guess: You nice analog simpson multimeter has a lowish input impedance so measuring voltage with it loaded the circuit, and if it was loading down a constant current circuit, the high output impedance thing, then maximum voltage reading would be lower than they should be? Not sure yet.

@w2aew 9 жыл бұрын

The low-ish impedance of the 260 appears in parallel with the current source, so the measured output impedance was dominated by the meter.

@Disillusioned_one 9 жыл бұрын

Analog meters can have a use, sitting my practical radio and television exams I was given a radio with a open cct 47k bias resistor. Part of my proof was to to put my meter on 2.5 volt range and placed the leads across the resistor and radio burst into life. Couldn't do that with a digital meter.

@w2aew 9 жыл бұрын

Yes, great tip! I love using analog meters especially when tweaking, adjusting and tuning circuits - so much easier to track changes with an analog meter. In 98% of the cases, the meter's input impedance doesn't matter. In 1% it does. And in another 1% it can be USEFUL as you've pointed out!

@robertcalkjr.8325 9 жыл бұрын

If they have the X10K which has the additional 9V battery like mine does, they are good for testing diodes and components to see if they breakdown under voltage also.

@robbowman8770 9 жыл бұрын

***** And they're nice things in themselves. It's 30 years since I used an Avo - my £9.99 Chinese multimeter is amazing, considering the price, but it's great to tune in a dial isn't it? I used to love doing bridge experiments with these in Uni. I feel a trip to eBay coming on ...

@k6eep593 9 жыл бұрын

How about a video showing how to measure a voltmeter's input load? I have some that are not labeled. I only use them for basic on or off voltage testing but it would be interesting to know a good way to test them. Kind of fun to test my meters to see if they meet specs too.

@w2aew 9 жыл бұрын

Usually, the best way is to measure the input impedance with a second meter. I have done this, and found on my Fluke DMMs that the input impedance on some ranges is 10Mohms (as you'd expect), but on some ranges it is closer to 11Mohms (not expected!). This can be important when using something like a HV probe. For VOMs, simply take the sensitivity value which is usually printed on the meter face (like 20,000 ohms/volt), and multiply that by the voltage scale that you have it set to. For example, if it is set to a 10V range, then the input impedance will be 200,000 ohms. Hmmm - probably worth a video...

@cny02253 9 жыл бұрын

There is no such thing as failure, there is only feedback. Where there is smoke there is a lesson. (or work!). A lot of experimenting is actually making deliberate mistakes. If things went too smooth, I would get nervous, or wonder if what I was doing was worth while. I learned nothing doing what I already knew how to do.

@robbowman8770 9 жыл бұрын

And that, ladies and gents, is engineering! Engineers make mistakes (shock horror!) ... so we go back and do it again. Kudos.

@Backtothefutureradios 4 жыл бұрын

Great demonstration!!! A question on the opposite angle......How can you simulate taking a reading on a tube circuit using a DMM as if you were using an analog meter with 1000 ohms/volt? As you can tell from my question....Ive ran into a big voltage difference using the modern DMM on certain circuits where the schematic show the recommended voltages taken with a 1000 ohm/volt meter.....I used a 270k ohm resistor to shunt the DMM leads....Im sure this is not exact, but I get closer readings.....Am I making the data fit? Or is this a correct way? Thanks--Larry

@w2aew 4 жыл бұрын

If you want to simulate the analog meter, you would need to the the voltage scale that you would have the meter set to. For example, If you would use a 250V scale, then the parallel resistor you'd need would be 250*1000, or 250kohms.

@yoramstein 8 жыл бұрын

Another graet video Alan. Even you don't forgive yourself for making that mistake (as it sounds) we your vieuwers do ! At your 60's birthday your CAKE is going to be a Simpsom Meter. *Easy to remember* _Allways_ try to load as less as possible circuit being measured (unless behaviour under load is the issue :-)

@warplanner8852 8 жыл бұрын

Frankly, Yoram, I personally think it disgraceful that Alan made that absolutely inexcusable error. He should think about abandoning the field of electronics forthwith and sell off ALL of his lab equipment immediately! So, Alan, what will you take for the Nixti tube frequency counter? Give you $25, OK? Just rank sarcasm on my part, Alan, of course! Your work - especially videos like these - are treasure troves of practical educational knowledge. And, besides, I scored this terrific old Eldorado 1650 Nixti tube counter myself. ;-} 73, de k6whp dit dit

@w2aew 8 жыл бұрын

Nice score on the Eldorado counter - more digits and functionality than my little Leader counter!

@warplanner8852 8 жыл бұрын

+w2aew..thanks! By the way, you *know* I am possibly your #1 fan.

@yoramstein 7 жыл бұрын

Do quit your war planning pls

@AlexeiPolkhanov 9 жыл бұрын

Wow, last time I used voltmeter like that Simpson was when I was 10 y old. I always assumed that all voltmeters have 10M impedance minimum. Now I have a QUESTION - looking at my Agilent DMM 34461A there are 2 options for "Input-Z" in DCV mode - 10M and "Auto". I looked at manual and it says "the Auto mode selects high impedance (HighZ) for the 100 mV, 1 V and 10 V ranges, and 10 MΩ for the 100 V and 1000 V ranges. In most situations, 10 MΩ is high enough to not load most circuits, but low enough to make readings stable for high impedance circuits". What kind of conditions exactly they are referring to when I can benefit from reducing input impedance in DCV mode?

@w2aew 9 жыл бұрын

Consider very high impedance circuits... Any tiny induced current in the test leads (acting like an antenna) can result in creating noise or variations in the measurement. In these cases, not having a huge input impedance can be advantageous

@Fusionx916 9 жыл бұрын

I just bought the troubleshooting analog circuits book from amazon.

@dcelctrl 9 жыл бұрын

Ok, Alan, please show us the effects of the burden voltage of the ampmeter shunt on the circuit. Would a MicroCurrent have been a better choice to measure the current with?

@w2aew 9 жыл бұрын

I'll take a look at it, but probably not worth a video in this case. But, a video about burden voltage in ammeters in general is probably a good topic to address in a future video. The +eevblog microcurrent would probably be a good thing to use to minimize the burden voltage, but I don't have one.

@JohnUsp 3 жыл бұрын

Maybe is better to measure the voltage on the 10K scale (because of the precision) AND Disconnect the VOM before measuring the Current. (or move to a high scale with more impedance) V 10.09V 5.00V 2.00V mA 0.420 0.394 0.378 (Simpson) mA 0.372 0.370 0.369 (Fluke) 0.048 0.024 0.009 (Simpson - Fluke) kOhms 24.0 12.7 5.3 (Simpson) 27.1 13.5 5.4 (Fluke)

@jp040759 8 жыл бұрын

I noticed you use the Simpson in several of your videos. I was thinking of getting one. I see you have a series 5. Based on schematics I have located it has a 1.5 volt battery and also a 6 volt battery. Where do you get a 6 volt battery for these. What series would you recommend getting since it will be my first one. I definitely want a series that uses 4mm banana jacks in it. Maybe the 260 would be a good subject for a video for beginners that are used to seeing digital gear.

@w2aew 8 жыл бұрын

+jp040759 I think my unit uses a four AA and one D cell. In fact, I keep the batteries out of the meter, and only use it for watching "slow" voltage and current changes - very useful when tuning, adjusting, tweaking circuits. The batteries are only used when measuring resistance, and I don't use it for that. All the info you could ever want to know about the different Simpson 260 series can be found here: www.simpson260.com/

@jp040759 8 жыл бұрын

+w2aew Thank you. Makes sense. Thanx for link. BTW Great vids!!!!! Always look forward to the next one to be uploaded.

@slhxfa1c0n51 9 жыл бұрын

can we built a constant current source given the voltage source we have is AC and it's constant. we need to vary the impedance and still the constant please answer am stuck.

@w2aew 9 жыл бұрын

Salah Reffis Rectify & filter the AC to a DC power source, and bias the current source with this.

@billwilliams6338 5 жыл бұрын

When using Fluke meters set on DC volts, when the DVM meter probes are measuring an OPEN or have the meter probes not connect it measures zero. Other DVM meters is randomly fluctuate a millivoltage on the the meters display when measuring an OPEN or have the meter probes not connect. I'm guessing Fluke puts a Low Pass filter that built in that can't be turned off when trying to measure an OPEN circuit? When you put the FLUKE meter in MilliVolt mV range the meter will randomly fluctuate a millvoltage when measuring an OPEN circuit but not in the normal Voltage range. This is the only way to know if you have an open circuit or the circuit has a ghost voltage is by using the Fluke millvolt mV range not the normal Voltage range?

@w2aew 5 жыл бұрын

The reason you see a random fluctuation is because the leads are acting as antennas picking up signals from the air. It is not a reliable way to detecting open circuit.

@crawdadsaf7 9 жыл бұрын

Hey Allen I commented on the previous video and probably should have commented here but could you have placed a high value resistor to mimic the digital meter? Just a rookie here.

@w2aew 9 жыл бұрын

This would minimize the parallel current path, but the VOM wouldn't indicate the correct voltage.

@MsFireboy2 11 ай бұрын

I would use the DMM meter before the old Simpson 260 analog meter. But do get me wrong the old Simpson Analog meter back in the 60’s and 70’s in my opinion was the industry leader. Your thoughts?

@w2aew 11 ай бұрын

I like using the analog meters when I can - which is when: - I want to watch the trend up/down - I don’t need high precision - loading effects are ok

@MsFireboy2 11 ай бұрын

@@w2aew Thanks. Also my electronics instructor stated there’s a time and place for each application. Have you done some op-amp output bounding before? I have been working on some circuits I find it very interesting.

@w2aew 11 ай бұрын

@@MsFireboy2 not sure what you mean by output bonding.

@MsFireboy2 11 ай бұрын

@@w2aew output bounding on op-amps is the process of holding the output at a certain level through the use of Zener Diodes.

@OneBiOzZ 9 жыл бұрын

won't measuring the current make even more loading across the shunt?

@emmanuelsuazo1318 2 жыл бұрын

Would this loading effect cause something to turn off? For example: our machine at work is running and when we check voltage the machine turns off. Then we take the probes off and it starts running again

@w2aew 2 жыл бұрын

Loading might cause that, as well as noise injected from the probes. Also, if probing from a non-floating instrument like a scope, real problems can occur if the probe ground isn't used properly.

@emmanuelsuazo1318 2 жыл бұрын

@@w2aew we are using multiple fluke 87 with the same outcome

@w2aew 2 жыл бұрын

@@emmanuelsuazo1318 The loading presented by a Fluke 87 (assuming you're measuring voltage) is very low. I suspect that the probes are coupling noise into your machine (whatever it is).

@davecc0000 9 жыл бұрын

Is there a simple way to construct a CC circuit that is not so sensitive to impedance?

@w2aew 9 жыл бұрын

Even *this* simple CC circuit is not sensitive to impedance! It simply had a 200k resistor (the VOM) in parallel with it, and the ammeter was measuring the total current (CC source + current in the VOM).

@davecc0000 9 жыл бұрын

***** So it is. Thanks Alan.

@KirkOfBellevue 9 жыл бұрын

Is there any benefit to the old meter these days, or, can it do something better than the new ones?

@w2aew 9 жыл бұрын

I find them vastly useful when tuning, adjusting or tweaking circuits while watching the voltage or current change. Much easier and more intuitive than watching digits or a segmented bargraph on a DMM. The 'inertia' of the meter movement is also good to visually average wiggles on a voltage. I like them for the same reasons that I like an analog tachometer in my sports car.

@vedantjoshi1487 7 жыл бұрын

i have a weird question......what does it mean by "w2aew"...??? :)

@w2aew 7 жыл бұрын

W2AEW is my amateur radio license callsign.

@lidarman2 6 жыл бұрын

When my multimeter reads 420 uA, I get out the pipe.

@xxJerry19xx 9 жыл бұрын

Why you just don't put this VOM meter before A meter ? Than you will have some error in voltage, because of voltage drop on A meter, but it will be small error because of small current and impedance of A meter. So in this case is better to connect VOM meter first/closer to source and VOM meter second. Or just use modern meters and you will have smaller problem with this. :)

@w2aew 9 жыл бұрын

Correct on all counts.

@maciejyt 9 жыл бұрын

In circuit with proper current measurement (voltmeter above current meter) error will be small not because low amp meter resistance but because we measure current source dynamic resistance. Current change in current source is very small and it produces very small voltage drop CHANGE on amp meter. So almost constant drop on amp meter will cancel in equation. And you can use also this Simpson old meter and achieve excellent outcome. It is better to use uA meter, because current change will be several uA, and source dynamic resistance should be about 4M ohm. I think you should delete these movies about current sources, and do a new one, because some young engeneers may be confused :) Thank you for your work on KZfaq. I really appreciate it. Best Regards

@BrendaEM 2 жыл бұрын

I appreciate all of your electronics videos, but that will not stop me from being really evil... ...Could not a board be made to replace the Simpson meter workings with an MOSFET/FET, or Op-Amp front end, that would have a much higher input impedance, and then couple it with a current source for the meter?

@w2aew 2 жыл бұрын

Certainly it would be possible to completely replace the guts with a FET input amp to get the benefits of very high input impedance.