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 ❤
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 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".
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 liked this video. A beautiful development, everything is clearly explained, and the most important thing is implemented in hardware. Thanks Leo for your work.
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 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!
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.
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.
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.
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 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!!!
I used the PCB from the link in the information here and soldered everything up and it works!! Thank you Leo and whoever the other guy is for this project.
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 :)
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.
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.
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.
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 did have a question though. I'm new to analog circuitry, and I'm wondering how R1,R2,Q1 work together to determine the minimum current threshold to turn on the circuit.
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.
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
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.
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,
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.
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.
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!!
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 am thinking of re-designing the mechanical portion for another video, maybe offer kits that can be purchased on-line that contain a finished PCB and some mechanical parts- you then can download and 3D print the case yourself.
If only RUclips algorithms stopped trying to promote TikTok style trash and instead, showed content like this where people can actually learn how to harness engineering and design tools to help them solve real world problems.
Now is obsolete! Next version is needed. 20 milliamps will blow the shit out of some modern semis. Some of the new microwave transistors cannot tolerate more than 100 microamps and have a breakdown voltage of 3 volts.
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..?
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 !
It's possible, but I have not tried this. You would need to modify the circuit to withstand the much larger amount of energy that would get past the very slow PTC. For example, R1 would need a TVS or Zener to limit the power dissipation. The PTC must have a relatively low cold-state resistance, or it would make the circuit malfunction. This implies a tricky compromise, low resistance PTCs trip at higher current levels.
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)
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
The opamp just needs to work right with an input voltage that goes all the way to ground. Of course it needs to be happy with a 3V supply voltage too. There are many opamp choices that could be cheaper, I never bothered to cost-optimized this design. Maybe I should do another episode where we do a real DFM, cost optimize it and come up with a mechanical design concept that would really make it a great product?
@@leosbagoftricks3732 I personally would love to see that. The jump from quick and dirty, bodged prototype to a finalized design is difficult, and a fascinating topic.
@@leosbagoftricks3732 The question of "why that specific component" is often a tough one for newbies, and I think it would be really helpful to have some treatment of that. Of course numerous parts could satisfy the parameters, but laying out the parameters is, I think, the step a lot of people are missing. And then saying "welp, I had some of these in my junkbox and they're close enough" is the next step for most hobby circuits! Taking it beyond that, to specific parts and supply chain availability and stuff, would be really neat. Personally, I would also love to see a discrete implementation of the Bourns black-box part, just for education's sake, even if that's not what goes into the final build. There are depletion-mode FETs with Vdss > 450v commonly available, I checked! :)
@@leosbagoftricks3732 ok tried out the idea of haptic vibration feedback- IMHO it sucks, when probing tiny stuff, the vibration knocks your probe off the thing you are testing
Hi Leo, I’m building this circuit, already ordered all the parts :) I have one question that is bothering me: why Q2 is biased via voltage divider? (Trying to adapt this to another project and I also need there a positive feedback for a transistor used as a switch, not as an amplifier)
I would really appreciate if you can make me understand this, everywhere on internet I seem to find voltage divider used in bjt amplifiers with another resistor on emitter. Thank you very much
Hello Leo I ask you to give me the way to reach this design with the calculations stage by stage ... because I am trying to learn from you the methods of designing electronic circuits ....Because I don't want to make it only, but I want to learn from it Thanks
The ability to do the calculations is important, but I always tell people learning Electronics to focus on intuitively understanding the concepts, rather than toiling over equations.
![BLACK BAG - Official Trailer [HD] - Only in Theaters March 14](http://i.ytimg.com/vi/Du0Xp8WX_7I/mqdefault.jpg)
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 ❤
Thanks - means a lot!
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 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 idea - fast response is a good attribute
The rare occasion of total agreement with someone elses perspective.Thank you very much
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.
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 liked this video. A beautiful development, everything is clearly explained, and the most important thing is implemented in hardware. Thanks Leo for your work.
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 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!
hi friend do you make this progect??
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.
Totally agree with your opinion on tools. Simpler tools bring you joy and efficiency.
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.
I have a feeling just sticking around I can finally design meaningful circuits. Keep it up!
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.
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 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!!!
I used the PCB from the link in the information here and soldered everything up and it works!! Thank you Leo and whoever the other guy is for this project.
I'm proud I found
your channel. Thank you for sharing, even more than your device, for your experience in design it. Cheers!
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.
This is a problem I've meant to tackle for a while. An excellent, to-the-point solution. Thank you very much for this!
Thanks for sharing many of your projects and advices. Your videos rekindled my long lost interests into discrete electronics.
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 :)
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.
Good morning Leo. I absolutely love how you laid this video out, using the KISS method for the design is great.
Nice work! We posted your video on our homemade tools forum this week, credited to you of course :)
yeah - great vid
Just like a continuity tester should be! Instant result! Thanks for sharing.
Damn that opening statement about that old tool was on point! (no pun intended)
Thank you for your videos, I love the focus on learning step by step with emphasis given to more complex ideas. You're awesome!
Built! Works amazingly, thanks for the work you put in!
excellent commentary, and i really enjoy touring the various elements of design
I love your videos - I am trying to learn about real world electronics - please do lots and lots more.
I am soooo with you!
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.
Nice design, well thought out!
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.
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 did have a question though. I'm new to analog circuitry, and I'm wondering how R1,R2,Q1 work together to determine the minimum current threshold to turn on the circuit.
@@jarrettdoesstuff2318 The current flow through R1 creates a voltage drop, when this voltage exceeds the Vbe (~0.65V) Q1 starts to conduct...
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.
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
Great video. Effective design methodology. Begin with the requirements.
Great video and design exercise. I wish I understood half of it but that's on me.
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.
Very clever design, your content is so amazing, I love it !
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,
The 1N5400 series diode has the same speed as the 1N4000 series
Thank you for sharing! Any ways you can do this remotely? Like being on the main panel and by an outlet upstairs?
Thank you
The 1N5400 diodes have the same speed as the 1N4000 series diodes too
I wanna know more
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 would love to see a design for that?
This rocked - great channel - I'm hooked!
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.
I was thinking the same thing. I'd still want a fire retardant box.
Dudes plastidip is your friend.
Clever design , thanks for sharing
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.
Thanks for sharing, I just build one and it works just fine .
I love that this thing lives on!
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!!
Wonderful explanation, thank you! Your shirt game is excellent too!
That buzzer sounds nice... Exact make/model??? Please and thank you.
I still have a long way to go. Have to go back and relook, till it makes sence,
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 am thinking of re-designing the mechanical portion for another video, maybe offer kits that can be purchased on-line that contain a finished PCB and some mechanical parts- you then can download and 3D print the case yourself.
I was unaware of the TBUs. They may be useful for my future designs.
If only RUclips algorithms stopped trying to promote TikTok style trash and instead, showed content like this where people can actually learn how to harness engineering and design tools to help them solve real world problems.
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
Thanks!
I'm going to make this in the future.
Nice discovery... new sub indeed! great job explaining the circuit!!
Now is obsolete! Next version is needed. 20 milliamps will blow the shit out of some modern semis. Some of the new microwave transistors cannot tolerate more than 100 microamps and have a breakdown voltage of 3 volts.
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..?
Probably rather difficult. Maybe using some depletion-mode MOSFETs?
@@leosbagoftricks3732 never knowingly used them :)
info on the size
Could you substitute nickel metal hydride rechargeable batteries at 1.25v nominal in place of the two alkaline batteries in this circuit?
Tester: Could you tell me more about the tester at 2:23? I was not able to locate it on Amazon.
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 !
It's possible, but I have not tried this. You would need to modify the circuit to withstand the much larger amount of energy that would get past the very slow PTC. For example, R1 would need a TVS or Zener to limit the power dissipation. The PTC must have a relatively low cold-state resistance, or it would make the circuit malfunction. This implies a tricky compromise, low resistance PTCs trip at higher current levels.
Maybe.. look at the DW01A BMS (Battery Management System) for a 16850 cell.
I wish you had a pcb of this. I'd buy a dozen.
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?
No, DC path only. The capacitor looks like an open circuit at DC
I like that you thought of almost every eventuality 😉👍. This is a continuity tester on steroids 🤔🤘
Thank you! Mr Leo
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)
We are NOT "testing" mains voltage- merely demonstrating that the device can WITHSTAND accidental mains voltage contact without damage.
@@leosbagoftricks3732 sir any alternate LBU components and can i use MCP6024 instead of MCP6022
New to all of this. Is there a parts list, or must I figure it out from the diagram?
Where to find a through hole circuit board type version of the TBU-CA050-WH?
Nope- they are SMD only
Thank you, I've learned a lot again. I'm looking forward to the next video. They have my Abbo and thumb.
Good job Leo
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
The opamp just needs to work right with an input voltage that goes all the way to ground. Of course it needs to be happy with a 3V supply voltage too. There are many opamp choices that could be cheaper, I never bothered to cost-optimized this design.
Maybe I should do another episode where we do a real DFM, cost optimize it and come up with a mechanical design concept that would really make it a great product?
@@leosbagoftricks3732 I personally would love to see that. The jump from quick and dirty, bodged prototype to a finalized design is difficult, and a fascinating topic.
@@leosbagoftricks3732 The question of "why that specific component" is often a tough one for newbies, and I think it would be really helpful to have some treatment of that. Of course numerous parts could satisfy the parameters, but laying out the parameters is, I think, the step a lot of people are missing. And then saying "welp, I had some of these in my junkbox and they're close enough" is the next step for most hobby circuits! Taking it beyond that, to specific parts and supply chain availability and stuff, would be really neat.
Personally, I would also love to see a discrete implementation of the Bourns black-box part, just for education's sake, even if that's not what goes into the final build. There are depletion-mode FETs with Vdss > 450v commonly available, I checked! :)
3:57 OMG I was gonna die if you didn’t fix that! LOL 😂! Thanks for te excellent video and idea!
I have been wanting one of these for a while
Awesome, now I have to design a pcb to make it happen as trough hole won't work.
Nice...I'd make that, but with an addition of a vibrator motor along with the buzzer
This is an interesting idea- I would want to mock this up and see how it feels when you use it.
There are tiny ones for cell phones... Cheap as I recall, in Ebay/Asian models, for EE hobbyist DIY applications...
@@leosbagoftricks3732 ok tried out the idea of haptic vibration feedback- IMHO it sucks, when probing tiny stuff, the vibration knocks your probe off the thing you are testing
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.
Hi Leo, I’m building this circuit, already ordered all the parts :) I have one question that is bothering me: why Q2 is biased via voltage divider? (Trying to adapt this to another project and I also need there a positive feedback for a transistor used as a switch, not as an amplifier)
I would really appreciate if you can make me understand this, everywhere on internet I seem to find voltage divider used in bjt amplifiers with another resistor on emitter. Thank you very much
Nevermind, beginer question :)
R6 is a pull down resitor… got it after more digging around.
Is the negative probe shorted to the case? could give a nasty shock on high voltage
No, it's totally isolated.
Hello, I did it. Very nice, thank you. The LED reacts quickly but it beeps too slowly. Any tips?
For those interested....just change the value of C2.
Greetings, Leo. Wouldn't the device be much simpler with a fuse to protect from high voltage ? 😊
Fuses are very slow - and once it's gone, do you have another handy? Probably not.
Instead of TBU, would "P6KE120A 120V Tvs Diodes Transient Voltage Suppressors" works?
No, you need a device that goes into a high impedance state, A TVS diode does the opposite
how quickly does it latch and also the beeper to light quickness?
Maybe 500 uSec?
Awesome! Thanks for sharing.
The only thing simple here is it's basic function.
Nice job.
Hi Leo great design. Is the TBU-CA050-050-WH difficult to solder with pads underneath? (I have soldered leaded smd parts before)
Hot air station makes this a simple operation.
@@leosbagoftricks3732 Thanks Leo I'll look into that.
Dear Leo, will 5V / 20mA not kill ICs, of the polarity is inversed.
This tester runs from 3 Volts, and outputs about 10 mA- but not at the same time! Probably never have an issue at this level.
Hello Leo
I ask you to give me the way to reach this design with the calculations stage by stage ... because I am trying to learn from you the methods of designing electronic circuits ....Because I don't want to make it only, but I want to learn from it
Thanks
The ability to do the calculations is important, but I always tell people learning Electronics to focus on intuitively understanding the concepts, rather than toiling over equations.
I want to buy that one
Why not insert a ~45 ohm resistor in series with your Fluke?
Because... hysteresis.
wow Nice! can you make a Continuity Tester wireless?
Very clever circuit!
Great circuit!