Suggestions for Fundamental Friday - Page 1
Forum section: electronics / general

author: AnalogFever
author_rank: Newbie
timestamp: May 10, 2013, 11:06:14 pm
content: First off, many thanks to Dave for his excellent takeoff on the first FF episode. It is very well done, smooth, and informative.I am wondering if Dave can do lectures on various bridges used in analog electronics such as Wheatstone bridge, Wien bridge, and Maxwell bridge just to mention a few.Of particular interest to me is the Wien bridge as I am trying to understand how this bridge is being used with rejection amplifier and bridge amplifier to null out the fundamental frequency in the HP334 Distortion Analyzer.I think these bridge circuits are great gems of analog circuitry as they were also used to measure the value of an unknown component like an inductor, before the digital meters became popular. I think there are other applications as well, so I am fairly confident that these would make for very good Fundamental Friday materials.Once again, thank you Dave and I look forward to see what you have in store for us.

author: Strada916
author_rank: Frequent Contributor
timestamp: May 10, 2013, 11:45:59 pm
content: And for the more advanced how aboutIntergrater circuits and there uses.dv/dt circuits and there uses.And for a little more advanced.La Pace Transforms and how they are implemented in electronics.Fast Fourier Transforms also how they are implemented in electronics.

author: jmole
author_rank: Regular Contributor
timestamp: May 11, 2013, 12:11:32 am
content: I want to see a confirmation, or a rebuttal of this video:

author: pickle9000
author_rank: Super Contributor
timestamp: May 11, 2013, 12:40:41 am
content: Electronics safety, not the rules but the concept.This is one of the best descriptions I have seen, and yes it involves ohms law. Of particular interest if the table that shows how dangerous punctured skin can be.http://www.mpoweruk.com/shock.htmI know this stuff but think there are many who do not.

author: NiHaoMike
author_rank: Super Contributor
timestamp: May 11, 2013, 04:28:06 am
content: What about sine wave vs. square wave inverters in motor drives? For a physical example, you could compare one of those Noctua fans (sine wave drive) against an el cheapo fan of the same size and power rating (square wave drive). Maybe even cover DSP drives that can dynamically vary the waveform based on operating conditions. (The Cindy Wu DSP drive technology in some high end Delta fans uses sine waves at low speeds for quietness and trapezoid waves at high speed for power.)

author: Corporate666
author_rank: Unknown
timestamp: May 11, 2013, 07:36:42 am
content: If we are talking about fundamentals, what about the big one... transistors. BJT's, FET's, IGBT's, diode drops, gate capacitances, Rds, level shifting, switching FET's with BJT's, unique uses for FET's (overvoltage protection, polarity protection, etc).It's an interesting topic, IMO, and many of the tutorials out there are either way too simplistic or massively overcomplicated with tons of math and dry minutia that puts you to sleep. There are so many examples that could be done as well.Another idea is EMI... what is it, what causes it, how to measure it, how can you avoid generating it through circuit layout or make your circuits less susceptible to it, or how yo mitigate it (i.e. snubbers). I bet a lot of people see that metallized spray on the inside of an enclosure and wonder "why do they do that, how does it work and what's the point?".

author: AndyC_772
author_rank: Super Contributor
timestamp: May 11, 2013, 07:49:45 am
content: I'd vote for something on high speed switching, decoupling, and why a breadboard is such an awful way to try and build a logic circuit that will work reliably. Talk a bit about power distribution, switching current and the effect of inductance in the supply lines, the benefits of using termination resistors and solid ground power planes, and about why you sometimes see double clocking when two chips are joined together over a distance.

author: Skimask
author_rank: Super Contributor
timestamp: May 11, 2013, 08:10:39 am
content: How about a F.F. all about how to ask smart questions?nah...that would take days, possibly weeks to drill into some people's heads...

author: Rerouter
author_rank: Super Contributor
timestamp: May 11, 2013, 08:27:41 am
content: feedback loop stability? its not really as fundamental, but a topic not many of us understand, and very important in most circuits...e.g. pole and zero compensation, bandwidth limiting, etc,.

author: justanothercanuck
author_rank: Frequent Contributor
timestamp: May 11, 2013, 10:34:45 am
content: One topic that comes up every now and again in one place I frequent is "how do I choose an op-amp?"...

author: TerminalJack505
author_rank: Super Contributor
timestamp: May 11, 2013, 11:20:17 am
content: Quote from: Rerouter on May 11, 2013, 08:27:41 am+1

author: codeboy2k
author_rank: Super Contributor
timestamp: May 11, 2013, 12:29:15 pm
content: Quote from: justanothercanuck on May 11, 2013, 10:34:45 amYes, that would make a good video topic, because it can be a place to discuss the datasheet information.my answer: more often than not, I have a specific characteristic that is important for a specific opamp in a design. Sometimes I need a low offset, or low bias, or sometimes that doesn't matter, and I need to operate up to 30 or 40V, and max supply is important. Sometimes I need both. Sometimes I need high bandwidth, sometimes output drive is important, etc.The other day, I was specifically looking for a DC opamp that was good up to 45V and could drive a 40mA load. That was my search criteria, and I just used the parametric tools on the manufacturers website to find some candidates. Then I drill deeper into the datasheet to make sure there is nothing to bite me, or that it fits all my other secondary requirements (is it unity stable, if I needed it, or what's the GBW? do I need to cascade another opamp because I am exceeding the GBW, will it's offset and bias harm me, if I care, etc)Yes, there's a lot to consider when choosing an opamp, I don't even think Dave can cover it all in one video

author: SeanB
author_rank: Super Contributor
timestamp: May 11, 2013, 12:44:28 pm
content: I had that with a piece of equipment that used OP07's there, i replaced them with 741's in a TO100 can and added a heatsink. Worked well, the original ones had overheated and had drifted badly, the new ones stayed cool. The application was only 12 bit, and the new opamps were perfectly happy there. At the time if I had to order the OP07's this would have taken 2 months, the 741's were in stock, and I had plenty that had been tested and had JAN-TX certificates.

author: c4757p
author_rank: Super Contributor
timestamp: May 11, 2013, 01:17:43 pm
content: Quote from: TerminalJack505 on May 11, 2013, 11:20:17 am+20

author: Neilm
author_rank: Super Contributor
timestamp: May 11, 2013, 04:35:54 pm
content: One thing that might be good Dave touched on in a recent episode. When tearing down the Uni-T UT513 he mentioned the Guard terminal. Now I know what this is and why I would want to use it but there are a LOT of people out there who don't - event ones using Insulation Testers at work.Neil

author: bullet308
author_rank: Frequent Contributor
timestamp: May 25, 2013, 03:06:57 pm
content: Not sure if it quite qualifies as a "fundamental", but I for one would like to see Dave take his DC voltage doubler to the next level and talk about high voltage, low current applications. Up to 2kV in the microamp or low milliamp ranges. But that’sjust me.

author: Alana
author_rank: Frequent Contributor
timestamp: May 25, 2013, 07:57:59 pm
content: Simple transformer based linear power supply. Sounds simple but i learned the hard way that this is tricky stuff with [as Dave says it] lots of traps for young players.

author: marvkaye
author_rank: Contributor
timestamp: May 26, 2013, 07:11:19 pm
content: Maybe not a great topic to detail on a whiteboard, but I'd sure like to see a presentation on external triggers... scopes & multimeters & other test gear have inputs for them but when and how and why do you use them? Advantages, disadvantages, traps, limitations, best practices, etc, etc...

author: c4757p
author_rank: Super Contributor
timestamp: May 26, 2013, 07:15:02 pm
content: Quote from: marvkaye on May 26, 2013, 07:11:19 pmI second this. The trigger is the most versatile and useful part of the scope. You could spend hours talking about how to use it properly, especially on modern digital oscilloscopes. (And don't forget the analog ones! Lots of tricks there that aren't needed on digital.) External is just part of that.

author: DarkPrince
author_rank: Regular Contributor
timestamp: June 09, 2013, 10:36:48 pm
content: I had a thought earlier of a discussion I (and probably others) could benefit from. A clear explanation of Q factor and its influence on circuits (especially tank circuits). For some strange reason I don't believe our university has a course which covers the topic (or a section of my memory is completely missing). I came to the realization of a lack of understanding when I was reading an article someone wrote about a home developed LCR meter and how the Q factor affects the devices measurements. Baffled why this wasn't covered in the uni. Just chucking the idea out there.

author: cthree
author_rank: Frequent Contributor
timestamp: June 14, 2013, 02:11:54 am
content: uC clocking, crystals, load capacitors and such would be an awesome tutorial.

author: azi
author_rank: Contributor
timestamp: June 28, 2013, 06:08:00 am
content: I would like to see Dave do a video about why anyone ever needs 5 or 6 digit accuracy for a multimeter.For what I'm doing now, 0.1% accuracy is perfect. I get more than enough accuracy without being distracted by extra information. As you can guess, I am not a gear freak.It's easy for technical people to be fascinated by a long string of correct digits, but in practice, what are they really good for?The only thing I can think of is when designing ADC or DAC circuits, and I may need to do that someday. But what else?

author: c4757p
author_rank: Super Contributor
timestamp: June 28, 2013, 06:27:32 am
content: How about one on the difference between accuracy and precision, azi?One quick example: I recently built an electronic load that uses a quite small sense resistor (0.01 ohm). At the specified 1mA resolution, that's 10uV steps on the sense resistor. I was definitely exercising the last digit of my 5.5-digit 3468A while testing and characterizing the current sense amplifier. I'd have loved another digit or two...I'm sure I could have found another way to do it. For instance, I could make it the lower resistor in a voltage divider, and then I could compute the voltage across it instead of measuring. But when a project is already complex, my will to complete it is inversely proportional to how much of a pain in the ass the little things like that are...

author: Unknown
author_rank: Unknown
timestamp: June 28, 2013, 07:48:05 am
content: Dave did a video about precision and accuracya long time ago. It's not like the meaning of those terms has changed in the mean time.

author: Smithy
author_rank: Contributor
timestamp: June 28, 2013, 08:41:59 am
content: I mentioned this in another thread but Id still like to see one on inrush current.

author: EEVblog
author_rank: Unknown
timestamp: June 28, 2013, 10:30:52 am
content: Quote from: azi on June 28, 2013, 06:08:00 amI was going to do something very simple along those lines, although for "resolution", not so much the accuracy part.It won't be a FF video, just a real quick simple video. Yep, could do this one in a few minutes.Ok, maybe 5 minutes...

author: casper.bang
author_rank: Frequent Contributor
timestamp: June 28, 2013, 10:47:56 am
content: Love FF stuff, especially as presented by Dave with theory followed by a breadboard setup - great for a rainy day while on vacation.How about the topic of hysteresis? I noticed it came up in Dave's latest multi-meter review, and I would not have known what it was, if I had not just been playing with ADC and battling the problem of "fast switching between two close states".Switch latching/de-bouncing could be another fundamental topic. There's a software aspect to these problems, so may be a little harder to cover, though unavoidable when BOM reduction is a concern.

author: Mr Smiley
author_rank: Frequent Contributor
timestamp: June 28, 2013, 03:15:59 pm
content: Hi,What do almost all newbies and seasoned designers hide from.Impedance matching using transformers, or for that fact, impedance matching full stopa X:1 transformer wound on a toroid, explaining what the load sees and what the source sees.Simple,easy to do, easy to demonstrate, but very frightening for a lot of people

author: Unknown
author_rank: Unknown
timestamp: June 30, 2013, 12:41:55 am
content: Quote from: cthree on June 14, 2013, 02:11:54 amI second this. I'm trying to figure out what the best way to hook a crystal to an AVR is.

author: jonwilhelmjr
author_rank: Regular Contributor
timestamp: July 26, 2013, 06:10:17 am
content: I would not mind seeing a video about filters for example RC filters. How many are they? Maybe Dave can do a series like he did with the charge pump and voltage double videos.

author: rakesh
author_rank: Unknown
timestamp: August 28, 2013, 11:09:41 am
content: Quote from: c4757p on May 11, 2013, 01:17:43 pm+1

author: ddavidebor
author_rank: Super Contributor
timestamp: August 28, 2013, 11:18:38 am
content: Quote from: jonwilhelmjr on July 26, 2013, 06:10:17 amBoooooring!

author: kizzap
author_rank: Unknown
timestamp: August 28, 2013, 11:40:45 am
content: Quote from: ddavidebor on August 28, 2013, 11:18:38 amand so is your negativity.-kizzap

author: Excavatoree
author_rank: Frequent Contributor
timestamp: August 29, 2013, 02:40:57 pm
content: I know a "datasheet" video has been proposed before, and I know Dave has shown some datasheets on previous videos and explained how to use one to understand a component, but I was thinking of a slightly differing idea.It may be helpful to do a series of videos on some basic components: Diodes, transistors, basic op amps,etc. Show the data sheet, explain the important specs, and maybe give an example of why one can or can not substitute component A for component B, and why or why not. (some cases are circuit dependent.)

author: Rerouter
author_rank: Super Contributor
timestamp: August 29, 2013, 08:27:49 pm
content: while i see that as a good topic Excavatoree, each of those components would really be worth there own video, there is a lot of things even at a fundamental level about a resistor for instance, temperature coefficients, noise, capacitance, winding patterns, materials, wattage, drift, breakdown voltage, etc,

author: Excavatoree
author_rank: Frequent Contributor
timestamp: August 29, 2013, 08:42:25 pm
content: Quote from: Rerouter on August 29, 2013, 08:27:49 pmThat's what I meant. Maybe one a month or so. "Fundamentals Friday - Resistors." for example, discussing the aspects you mentioned.

author: Kjelt
author_rank: Super Contributor
timestamp: September 07, 2013, 01:52:38 pm
content: Maybe designing and choosing the right components (which have their quirks), for instance like a standard ceramic X7R vs NPO SMD capacitor, capacitance derating (Voltage and Temperature Coefficient, last year this got even the pros at our company in trouble.

author: helge
author_rank: Regular Contributor
timestamp: September 20, 2013, 09:40:49 am
content: Clock/frequency generation, especially PLL-based!Be it in FPGAs, Microcontrollers or even in that bloody 74HC4046- based tesla coil you built over the weekend - we cannot hide from it. I'm currently digging into this subject for a project that implements a serializer with fine adjustable bitrate. PLL clock synthesis in particular is a whole world in itself. After Dave has tackled FPGA basics and JTAG in some videos I am confident he won't crumple in the face of sigma-delta fractional-N synthesis ;-)Here's some stuff to get started:http://www.skyworksinc.com/uploads/documents/101463b.pdfhttp://www.ece.ucsb.edu/Faculty/rodwell/Classes/ece218b/notes/MTT_2004_meninger_IntNFracN.pdf

author: george graves
author_rank: Super Contributor
timestamp: October 12, 2013, 06:26:20 am
content: Quote from: cthree on June 14, 2013, 02:11:54 am+1

author: TMM
author_rank: Frequent Contributor
timestamp: October 17, 2013, 03:36:54 am
content: I know it has been covered before (in one of the Agilent multimeter teardowns, i think?) but perhaps a more comprehensive tutorial of integrating ADCs.

author: helge
author_rank: Regular Contributor
timestamp: October 17, 2013, 10:56:25 am
content: Quote from: TMM on October 17, 2013, 03:36:54 amLet me start by adding a helpful piece of information:http://www.latticesemi.com/~/media/Documents/ApplicationNotes/AnalogLayoutandGroundingTechniques.ashx?document_id=1116

author: ShaunAndFRED
author_rank: Contributor
timestamp: October 27, 2013, 08:02:24 pm
content: I think one that would be great for FF is isolation. Why certain systems are isolated vs not, maybe even get into creepage distance and pcb slotting.

author: awallin
author_rank: Frequent Contributor
timestamp: November 04, 2013, 09:22:49 pm
content: Quote from: ShaunAndFRED on October 27, 2013, 08:02:24 pmI suggest: "how not to kill yourself with a variac"

author: con-f-use
author_rank: Unknown
timestamp: November 05, 2013, 01:18:13 pm
content: Wasn't aware this thread exisited. Howto not kill yourself with a variac is kind of similar to what I'd like to see, ageneral tutorial on mains safetywith focus on equipping your lab for mains safety.General vicinity:Isolation TransformarsRCDVariacsMains FiltersUPSsEmergency Shutdown SwitchesFuses

author: codeboy2k
author_rank: Super Contributor
timestamp: November 06, 2013, 01:04:20 am
content: Quote from: con-f-use on November 05, 2013, 01:18:13 pm+1 voted up

author: Syko_
author_rank: Contributor
timestamp: November 13, 2013, 12:34:35 pm
content: Just throwing this in there, for what-the-heck-ness.Hysteresis losses and Eddy current losses?