You should create and sell a diy kit...with a small booklet explaining each components purpose and function.. it would be a great project for students, beginners and those looking for a useful electronic project.. Thanks for this worth while video!!

Dude I just found your channel a few days ago and I am incredibly happy I did. I tried to learn electronics two times in uni and failed, it was just so theoretical I could not keep up. Now I started a video course that is much more practical and seeing your videos with this honest, structured, no frills approach to sharing your knowledge is exactly what I need to push me through. The more I learn, the more I understand and the more I feel like electronics isn’t incomprehensible black magic but something I can understand and use. Your editing style is simple and effective, your explanations clear and concise, and your motives are (or at least seem to be) honestly altruistic. This is the content youtube needs and the content that deserves millions of views. Thank you so much for making it ❤

I'd like to say a massive thank you for your circuit. I don't have the exact parts but i do have the equivalents, after making them i realized I've used it more than i could count, it's there, it's ready, it's convenient and durable. Even my teacher likes it.

Excellent deconstruction, Leo. Thanks for taking the time to show how you designed an awesome tester.

Good morning Leo. I absolutely love how you laid this video out, using the KISS method for the design is great.

Just stumbled upon this channel on an unrelated search, Excellent videos, learning new concepts already! Thanks for making them and can't wait for more.

I really like your video's, content and especially the presentation. Excellent voice quality, clear, concise, with some background usually thrown in. The design puzzle you went through seems very logical, and shows how one works through issues one step at a time. +1 for casual Friday attire instead of what appears to be YT default t-shirt.

I have a feeling just sticking around I can finally design meaningful circuits. Keep it up!

This is a problem I've meant to tackle for a while. An excellent, to-the-point solution. Thank you very much for this!

Thank you for your videos, I love the focus on learning step by step with emphasis given to more complex ideas. You're awesome!

Thank you for a very clear discussion of both design principles and the nitty gritty of developing a circuit to solve the problems which I might not even have thought of. As a beginner I found it invaluable to see such a clear statement of the problems and how the values of components are calculated to solve them. I will certainly build this tester, subscribe to your channel and look at your other videos.

I really liked this video. A beautiful development, everything is clearly explained, and the most important thing is implemented in hardware. Thanks Leo for your work.

Love this video, built one and it works great. built on one sided copper clad board. Used a combination of scratch and sniff and island cutting method method for soldering the TBU and SMD components ,resistors and diodes. I had to read all the comments section to really understand how it signalled the < 5ohms beeper works. Beeper beeps at around 3.4 ohms or less yet the current registers on the red led up to around 470 ohms then nothing. Learned alot building this. Thanks Leo.

Thanks for sharing many of your projects and advices. Your videos rekindled my long lost interests into discrete electronics.

Very clever design, your content is so amazing, I love it !

excellent commentary, and i really enjoy touring the various elements of design

This is great, thx. love that box. "I don't want to be distracted by anything except the project I'm working on." Speaking to my soul.

Built! Works amazingly, thanks for the work you put in!

I am going to make one of these for sure. Been an Electrician for over twenty years and for the last ten years I have been working on an Army Air Force base. So I have had to learn how to troubleshoot runway lighting. And a properly wired runway circuit should be about 15 to 50 ohms from one end to the other and trying to find an open circuit with a regular multimeter is a nightmare!

I work in software.... we make SO many really really bad tools designed for salesmen and not users.... more people in my industry need to listen to your intro to this video.

I love the way you think. You have great ideas and I appreciate how you manage to put it down so compactly and logically in a video. I'm a bit scared of doing the SMT stuff myself.. even though most of the real good goodies I find are like SMT only a lot of times. But yeah, doing it seems so scuffed, I"m already terrible at 'normal' soldering haha.

Excellent stuff. I may need to build something like this for a research project, although I think the tolerances I need are different (and specialized rather than generalized), mainly it needs to detect continuity in the microvolts range. This will be a great jumping off point, thanks a lot :)

Nice design, well thought out!

Thanks for sharing your circuit idea. I immediately proceeded to build this circuit using slightly different parts. No problems at all with the functionality of the circuit. The only thing I have to point out is that I decided to omit capacitor C2 (10nF) which caused a delay of about 45ms until the input voltage at th Op-Amp falls from 3V to 50mV when continuity occurs at the probes. This is a problem when you are searching for connected traces on circuit boards and slide the probe too fast so that you can miss the beep. So I advise to omit C2 or at least make it 10 times smaller (1nF) so that the delay is no more significant. Thanks again. This device is something I really needed when repairing unknown circuits where reverse engineering is required without switching the multimeter on and off all the time or worrying about the battery when leaving it "on".

Great video. Effective design methodology. Begin with the requirements.

Totally agree with your opinion on tools. Simpler tools bring you joy and efficiency.

Just like a continuity tester should be! Instant result! Thanks for sharing.

At last, I’ve found your channel, this is what it’s about. I’m 74 (never to old to learn) A to Z and nothing in-between in old radio’s. live in England (someone has to) thanks for you time and skills.

The rare occasion of total agreement with someone elses perspective.Thank you very much

Nice work! We posted your video on our homemade tools forum this week, credited to you of course :)

Wonderful explanation, thank you! Your shirt game is excellent too!

I don't know if your reading these anymore but I just ordered all the parts and decided to go with the other guys updated design. I would have never even tried this if you hadn't put up this video which really helped me understand. This is my first project like this. I will admit, I chickened out a little bit and ordered the board from JLC PCB using the other guys PCB design. Regardless, I can't wait to get started Thanks again Leo!!!

This rocked - great channel - I'm hooked!

Nice discovery... new sub indeed! great job explaining the circuit!!

I love your videos - I am trying to learn about real world electronics - please do lots and lots more.

Thank you, I've learned a lot again. I'm looking forward to the next video. They have my Abbo and thumb.

Clever design , thanks for sharing

Great video and design exercise. I wish I understood half of it but that's on me.

Thanks for sharing, I just build one and it works just fine .

Good job Leo

Really nice work

Another great video!!

Thanks! I'm going to make this in the future.

I have been wanting one of these for a while

Very clever circuit!

Love this channel 👍

Thank you! Mr Leo

Awesome! Thanks for sharing.

Great circuit!

Damn that opening statement about that old tool was on point! (no pun intended)

Thanks for this! I might build one up for myself. I always seem to need a continuity tester at the same time I'm using my meter for something else, haha. And the "always-on, don't need to turn a dial" is a big plus too...

I was unaware of the TBUs. They may be useful for my future designs.

Good job dude

Congrats!

I am soooo with you!

Love it! My biggest gripe with common mulltimeters is how SLOW they respond in continuity testing. I want it there, straight away: YES, or NO, and move on.

awesome great video !

I like that you thought of almost every eventuality 😉👍. This is a continuity tester on steroids 🤔🤘

Great video

thanks Leo !!

This is a great design. It's inspiring me to design something similar I've had in mind for a while, and that's a low voltage continuity checker. Something with an open voltage of about .2V, so that it won't bias any diodes, and I can use it to test actual continuity, not circuit path through active devices. I used to have a Beckman DMM that had a setting for 'low power ohms' that would do that, but all the modern dmm's seem to intentionally light up diodes, so to speak. That's not helpful when I'm testing wiring and traces, rather than the circuit.

Excellent !

I love your channel.

Thank you for sharing! Any ways you can do this remotely? Like being on the main panel and by an outlet upstairs? Thank you

Thanks I almost didn't watch, but was very pleasantly surprised. Added this to my "want to build" list. Also figured I can get you out of 666 hell.

this is what im looking for, God bless

Good video.

thank you!

good job

Thanks🙏

Thank you

I wish I could build one of those! I have burned 2 extech already cause I forget power is one. Plus it would be awesome if we could test a single wire remotely.

Super cool

Built circuit using all parts as shown in schematic. Circuit does work except my threshold is under 2 ohms before beeper comes on. Used 1% metal film resistors. Wonder if anyone else experienced same result? Other than that it does work as designed.

Great video and I can stand behind your reasoning on how tools should be :) I hate tools that can be used for 63 different things but not be ideal for any of them. I will definitely give your build a try, but I have one problem -- MCP6022 is not available in my location at any supplier. Looks like close substitute would be TLC272. I was wondering if any other more common dual op-amp would do? Thanks in advance!!

Could you substitute nickel metal hydride rechargeable batteries at 1.25v nominal in place of the two alkaline batteries in this circuit?

Great!

For Q1 I'd use MPSA94 and for Q2 I'd use MPSA44, these two transistors have a VCEO of 400 volts and they can handle twice the current of the 3906, 3904

sir your idea behind it and the view of respecting the workmanship is awesome ,thank u for such videos .( pls clarify sir the concept of testing LIVE and NEURAL wire ,what can be conclude from it)

New to all of this. Is there a parts list, or must I figure it out from the diagram?

we would like to use like that a device but feedback voltage makes fault even this works in this kind of sytem without any feedback voltage

That buzzer sounds nice... Exact make/model??? Please and thank you.

Instead of using a TBU (expensive and hard to get), you can use MOV with PPTC. Also a crowbar circuit should work as well. Use a triac instead of a thyristor.

I've been trying to find a good multimeter to buy with decent continuity testing. so far, every single one i've tried was very flakey. They would all beep for a second, then stop, then beep again, then stop, all while holding onto points, or even just holding the probes together. So far the best one I have is the little pocket multimeter i got from RadioShack a while back.

Thanks for another excellent video Leo. Can you discuss the choice of OP amp, or will any generic Rail to Rail OP amp suffice (ie. is there any particular characteristic of the MC .... that you depend on for the circuit). Thanks

It is a good simple tool. In 1959 I built a new VTVM and when done it did not work. I had np test instrument. So I took some wire flashlight bulb and a D cell like your circuit. With that circuit I tested each wire until the bulb lit up.

6:21 would this also cause it to trigger if there was a capacitance between the two test nodes, even if the path was a bit more than 5 ohms?

For D2 I'd use a more common diode like the 1N4006, lately I've discovered that the 1N4000 diode series isn't as slow as I once thought, it will work up to 1500 NS (1.5 MS) and 2000 MS (2MS) for the 1N4007 or the high-speed diode 1N4937,

Nice! I balked a little at the electronic fuse device because I tend to use parts from my limited stock of relatively common components. Which leaves the puzzle, how would you make such a thing from discrete transistors..?

This is a great design! If you sold them, I would buy one. In fact, it is just the circuit board soldering that is my hurdle. If you made and sold just that piece, I could solder on my own test leads and battery pack without making too big a mess of it. Regarding your first improvement (adding a threshold at 4:42), you have 2 resistors in the circuit R1 82, and R2 240. Do these resistors need to be exactly those settings, or is there a range of resistance for each resistor for the circuit to still operate correctly? Still learning!! Thanks.

I wish you had a pcb of this. I'd buy a dozen.

how quickly does it latch and also the beeper to light quickness?

Where to find a through hole circuit board type version of the TBU-CA050-WH?

Awesome, now I have to design a pcb to make it happen as trough hole won't work.

Is the negative probe shorted to the case? could give a nasty shock on high voltage

Hi Leo! I saw your video and I like your very practical point of view. I work like an electrician in Constanta Shipyard ,Romania. I work many times with large bundle of cables and I was searching for a very robust continuity tester like yours ,practical without many fancy functions, in a few words ,one to do its job and nothing more. I also like very much the way in that it is protected of accidental high voltages ,a very important function which has it. I would very much to build one like yours but unfortunately that TBU suppressor type is not available here, in the place where I live. I wonder if I can change that TBU with a PTC fuse resistor or you can help me with a solution .I want also to mentioning that phase voltage is 240v AC in my country and peak voltage is somewhere at 338v. Please excuse any grammatical errors because I am not a native english speaker . I will thank you in advance for your answer if I willl get one. Best regards !

I like it, except for the metal box. There's a reason that devices that might be near mains voltage are in non-conductive cases.

Hi Leo great design. Is the TBU-CA050-050-WH difficult to solder with pads underneath? (I have soldered leaded smd parts before)

Hello, I did it. Very nice, thank you. The LED reacts quickly but it beeps too slowly. Any tips?

Instead of TBU, would "P6KE120A 120V Tvs Diodes Transient Voltage Suppressors" works?