In this supersized lecture length episode, Dave foolishly attempts to explain how to design an example product (the uCurrent) from start to finish. The Full Article: www.alternatezo... See also: www.alternatezo...
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@hla27b Yeah, in all that ranting I forgot to mention the battery life! More than 200 hours. I determined that it wasn't worthwhile to add an auto-off function to this first version, as that would have required an intelligent device to do it properly.
From urban dictionary: schmick 1. I say this in Australia to mean anything sick, cool, tight or excellent. Usually the item is new, shiny, fresh and mad bling-bling style.
It's definitely a great video, but the problem is that nowadays the Chinese will knock off any product despite its patents, and often butcher the design of the original product. It's a nightmare once one has spent countless hours developing, building, debugging, and marketing their product.
@@BillAnt Don't worry about it, because they don't tend to make counterfeit products if it is not sold over thousands, the circuits like this will not be copied because of feasibility.
@@myetis1990 < I'm not talking about about small run products, but in general. Feasibility? Anything is feasible, it's just a matter of return on investment. I've read that in a particular Chinese city there are actual factories which only do counterfeit products. They have reverse engineering departments, along with China's lax intellectual property laws, they can operate just like any other factory. It's sad but true.
You actually can use a reversed LED as a light sensor, with some careful filtering and amplifying. But obviously it's inferior to proper light sensors (e.g. LDR, PT, PM).
Dave you are amazing man. Thank you soo much for sharing with us your design. I am so happy that here are ppl like yourself who manage to find time to show, explain and put on youtube videos so that we could watch and learn. I am shaking your hand and saying "Thank you Sir, we are glad to have you as our teacher "
@xspoonedx Interesting question. If you have the LED operate the other way around and have it only come on when the battery is low, then if you go to turn the unit on and the battery is completely flat, then it won't come on and you'll think your product can be used. So in this case (with no power LED), it's better to have it the other way around so you can check the battery is OK before you use it. So you could say it's more important to know that battery is OK, than know if it's flat!
Just wanted to say, love the videos man. I've been an electronics hobbyist since my teens (Amateur Radio operator since age 14 and I dabble in guitar amp and effect design/repair as well). I finally took the plunge and enrolled in a BS Electrical Engineering program this year. After 7 years of working security all over the world I'm definitely ready for a career change haha I have several similar channels I follow but the wit, sarcasm, and humor you bring to the videos definitely make this the most enjoyable to watch. Not to take away from the value of the other channels but some can have a very dry delivery of the knowledge. Great channel, and keep it up. -KC9FJE
@@hansdietrich83 In all cases, every pole of the (ganged) switch is connected through to itself, unless it needs to function in a non-ganged configuration, and then I admit I don't know what the purpose of the circuit is. If they are truly ganged, this means an optimization can take place. If you used the poles of the switch to select which input resistance you need, into a common input node to the op-amp, then yes it CAN be reduced to a single pole triple throw switch. Simpler design means less prone to failure. I think Dave would agree.
There is an alternative configuration that Dave neglected to show which only uses 2 banana jacks, and a single SP3T switch. Wire the 3 poles of the switch to each resistor to ground. Wire the common from the SP3T to the input banana jack, as well as the op amp input.
I had bought an electronic blanket from a second hand store. It worked great I thought. It only used 8 watts. I thought "wow they have cone a long way. 8 watts nice.' then it broke a few years later. I went to buy another one to find out that I could not replace it. Every blanket I got was at least 150 watts. Devistated I didn't know what to do. I live in my RV. And to have an electric blanket that I could use for 3 or 4 days on my batteries was I wonderful thing. To use one that eats up 150 watts they would be dead in no time. 1 to 2 hours. The one I bought from the second hand store was clearly defective. But for me, it couldn't have been better. I need to find a way to bring a new blanket from 150 watts to 8 to 15 watts. So many of us love in RVs. And then there are the penny Pinchers. This would be a great thing to bring to market. Who needs 150 watts? That gets so warm it's uncomfortable. Can I just add a resister to the board somewhere to bring that down? Please help. And if you can't, can you point me in the right direction?
I'm incredibly impressed. These should be selling by the truckload. It's elegant, compact, functional, ergonomic, producible, and economical! You just proved that simple is better. Your attention to detail shows the importance of creative skills that many engineers lack. Most engineers likely forget about how the product feels when they get too caught up in the circuit. Yeah, their circuit might be good, but it looks and feels like garbage.
@BitEntropy No, the LED does not switch on if you move the switch quickly enough, a nice side benefit. It's easier to move the switch all the way to one side than centre it, so it's easier to switch it off.
37:53 when I realise that the thing is bright red instead of the normal phenolic cacky brown, and it's like that on purpose not cause you cheaped out on the solder mask.. The joys of being colourblind :P
@oehrlein49 I use PCBcart, cheap and plenty of options. No special deals for Altium Designer unless you are a student. Otherwise it's $3900/year or $5K outright for the PCB version. That's less than half the price it used to be.
About 45:xx I was thinking "how do you test the outputs" and the following discussed how to test for interference. Would be interested in seeing more about verifying the outputs to be correct.
absolutely brilliant video, really helped. My only question (from a noobie perspective) does the 100 ohm resistor that provides overload protection affect the final readings? Surely they will in series with the 3 resistors you can choose from? Many thanks!
David Mason Solo la afecta en un 0.0001%. El MAX4239 entrega su tensión sobre el divisor formado por el resistor de 100 ohm y la impedancia de entrada del voltímetro, que es del orden de los 10 Mohm. Por lo tanto el 99.999% de la tensión que entrega el MAX4239 es leída por el multímetro.
I took a crack at deciphering the uCurrent schematic but a few things were leaving me scratching my head. This explains everything so clearly. In the first 25 minutes of this video I've gained so much knowledge.
Thanks Dave. You have inspired me to design my own dual power / microprocessor controlled lab power supply. I don't really intend to sell it, but thought it might be a great challenge and something to concentrate on, after work and on weekends. About 75% there... as of today.
This is such an interesting video. I love seeing how you develop that circuit and the thoughts and considerations that go into the product. I stopped watching TV a long time ago and started watching videos like yours.
@gameboygenius - If you were using AAs your idea of using 3 would allow use of NiCads/NiMHs (whereas a 2 battery design wouldn't (only 2.4v). I like this versatility. But rechargeables aren't ideal for an occasionally used low-drain piece of test equipment due to internal discharge, so accommodating rechargeables isn't as big an issue. Although generally I like using an even number of AAs as they come in 2s and you don't have one left over when you need to change them.
Or anyone interested in Designs in general.. As products of universal inherent quantization "computation".., default time-timing designs, ..of course the elemental mechanisms are of total importance. Functional Devices focus attention on what, how and why.
A pitty that Dave did not respond on your legitimate remark. A "battery low" indication would show during measurements that the battery voltage came to low and not only when switching to power on, where the battery would come from a no load, recovered mode.
I find the real problem is how to design the front panel and how to imagine switches that can operate deep inside the boxed housing electronics. I think it becomes a mechanical engineering problem which strays from all the effort and excitement of realising the design. What's needed is that front end design handled by some computer process so that the electronic engineering is separated from it's commercial realisation but is automated if the design is taken to fruition by paying the cost.
I love all your videos. But this video is totally unrealistic. Usually when designing, you have some boss breathing down your neck about time, $, etc. And where is your coworker with that annoying habit that drives us nuts?! Seriously, I really appreciate you doing these videos. Instructional and entertaining!
So, I think I will just do a "parametric" search for multimeters that have the same or better current range as Daive's Device here. Stellar work here by Daive. An engineer can create for $10 what any person in a garage would need $100 to make.
Your approach to subject is lucid and spot on. But I have one point to make. Can you not design chopper stabilized amplifier to combat voltage drift? Whenever we measure low voltage this drift is comparable to input voltage being measured.
I love all your videos. But this video is totally unrealistic. Usually when designing, you have some boss breathing down your neck about time, $, etc. And where is your coworker with that annoying habit that drives us nuts?! Seriously, I really appreciate you doing these videos. Instructional and entertaining!
This is a great idea, but you would think multimeter companies would just add in smaller loads and an amplification stage in their meters. Is there any reason why this isn't already incorporated in most multimeters? Assuming all DC measurements, I don't see why not. Maybe power?
lol what did he say at 10:30?? i thought he was glitchin out for a second lol :p i had to rewind n watch it i was workin on somethin so i just heard it the first time
Actually wouldn't it be possible to build this with an opamp working as transimpedance amplifier? That should (theoretically) lower the shunt resistance to zero and the shunt resistance was the main driver behind this project right?
when you said the product was included in the 2009 catalogue, I thought you might have been taking a trip down memory lane, until I noticed this video is almost 11 years old. great standard of video for the time, and today!
I watched this over the last two nights with my 4 year old inventor son, for his bedtime story :) To his credit he was really listening for the first 10 minutes of each 25 minute night... and he loves the way you say "banana" Dave. I really enjoyed the video and all of the information. Thanks for taking the time to put it together!
Excellent video Dave, instead of fortuitous one may even say "elementary my dear Watson". Love the look of the end product, where can I buy one here in Australia?
If you could make the PCB quick to open by using a hinge or a magnet etc. then you would be able to store banana cables in the box to connect the output to your DVM. Or leave it as is and secure a spare battery in there. Or slap some googly eyes on it and "Bob's your uncle".
Dave, it's one of Your older videos. After few dozen of projects, i have to tell You that You opened my eyes and showed me how to do stuff. I'm so glad and thankful... I want to buy You a coffee and meet in 4 eyes :) Maybe one day i'll visit Australia. I hope to do so.
A subtle little thing... If I were to use AA/AAA's for this project I might've used three batteries instead of two, to avoid wasting battery power and having to switch batteries more often than needed. (2.6V/2=1.3V/cell vs 2.6V/2=0.87V/cell) Of course you'd have to consider battery impedance and such. Which brings me to something I'd like you to speak about when seeing this: The black art of bypass capacitors, which would probably deserve an episode on its own merits.
Dave, I just saw this great video! Better than a book! Better than a seminar! Better than college courses! You have inspired me to follow through on an idea I have DaveCadded. When done the finished product will be much better because of your generosity. THANK YOU AND KUDOS TO YOU!
Thank you for such a great tutorial. I wish I saw this job long before. One thing I wonder about PCB layout, is there any countermeasure or consideration for precision measurement (opamp stage)? The second thing is how should protection be for overcurrent?
When you talk about contact resistance needing to be taken into consideration takes me back to in tech school how we took "ideal"components most of the time but even "simple"pieces of equipment you have to be very precise.like taking even say the resistance of conductors or stray capacitance into consideration.enjoyed the presentation.
one more thing you can use op-amp if current usage less like 10 ma (max output of current of opamp) you can use tl431 its even cheaper and current is upto 100ma and can use a transistor to increase current
I'm 3 minuets into this things and I can already tell you've knocked this one out of the ball park. I'm going to grab a beer and some popcorn and enjoy my next hour of engineering bliss. Cheers. George Graves
Wow Dave 51 minutes and you didn't waste a second. I couldn't fill 51 minutes in front of the camera. One question, how long does the battery last? Say if you forget it switched on?
Ten years late to the show, but love the content. Was trained in electrical engineering and took a different path, but wanted to get back in as a hobby. This was exactly what I was looking to walk me through the thought process. Love it!
Nice product... but why don't the multimeter companies build that functionality straight into the meter? Forgive me if there is a really obvious reason I'm missing.
Great advice ! did you make a video about the decisions made when you decided to make the Gold version ? that would be so useful to have you thoughts on the products evolution.
