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Hello , I tried to check the stability of the circuit by opening the feedback loop and placing the pertubation as shown below. How ever I made two plots Vf anole and Vf,Vin in AC responce and I get quite different result. What is the proper way to test feedback responce? Thanks. /g/electronics101/files/john233/classA_driver_new.asc /g/electronics101/photo/296358/3872575?p=Created%2C%2C%2C20%2C2%2C0%2C0 /g/electronics101/photo/296358/3872574?p=Created%2C%2C%2C20%2C2%2C0%2C0

I'm a sucker for test equipment, more so for good equipment at rock bottom prices. A friend dropped an inexpensive audio oscillator by for me to check out. https://www.akitika.com/1kHzOscillator.html#:~:text=Distortion%20is%20very%20low%2C%20typically,only%202nd%20harmonic%20is%20visible.) This oscillator has a claimed distortion of 2 parts per million (0.0002%). I only have access to test equipment that can measure down to 0.001% and this oscillator's distortion was lost in the noise floor of the test equipment. The frequency was slightly off, well within specs but 1002.31Hz. At $89 this represents an amazing value. Yes you can download their assembly manual and "roll your own" but I doubt you can achieve the performance of this unit. Part of their magic is their PCB layout and hand selecting the frequency determining devices. It isn't worth my time and energy to try and copy their PCB and locate accurate parts. I'm well know as a cheapskate and I ordered one.

I was given this little thing a while back, haven't done anything with it yet... There's this board, no particular identifying marks on just what it is. The oddest BNC I've ever seen on top, some switches down the left side that seem to be for selecting sensitivity and coupling, some DC input connectors on the top to power the thing, five buttons labeled OK, +, -, SEL, and RESET. A couple of pin headers and a USB micro connector on the bottom. A plug-in board labeled "2.4" TFT LCD. Two bits of paper came with it. One is labeled Oscilloscope DIY Kit User Manual but it seems to be assembly instructions. This bears the numbers 138803K and 13804K, no indication as to which unit I have here. The other paper has "How to Use" calling out the "Display and Controls". And some stuff about "probe calibration". On the back of that one are schematics that are barely readable. With a magnifying glass I see them showing power input as "9.39V". (!) Apparently some of this thing runs at 3.3V also. There's no case, though I'm told that one is available. Not told where, though. Have any of you guys run across anything like this? I'm a little dubious as to how useful this thing might turn out to be, haven't yet gotten around to digging out an appropriate wall wart to power it up... -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, a critter that can be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin

If you are only interested in looking at audio on an oscilloscope, one decent method is to use a "high quality" USB audio interface. The Behringer UMC202HD is a decent unit that can be found at several music stores for around $100. Behringer enjoys a mixed reputation, apparently if you get a good unit they will work fine "forever." My three have been in nearly daily services for 4 years now. They are used as the analog to digital converter as a test instrument and to feed AF into a PC for audio analysis/decoding on a shortwave radio and one is used as an actual musical instrument input device. This circuit is used for the oscilloscope input conditioning. PC Oscilloscope Interface https://sound-au.com/project154.htm And these circuits are used for radio to PC, PC to radio PC To PA System Interface https://sound-au.com/project133.htm I used parts I had on hand so my circuits are slightly different. We use similar circuits to feed PC to/from our church's PA system and I carry a pair with my laptop just in case I find myself pressed into service as PA source or recorder. The PC to PA system interface will also function as a basic PC oscilloscope interface. For those who wish to study audio distortion, Mr. Elliot has some interesting, and downright weird, techniques. Intermodulation - Something 'New' To Ponder https://sound-au.com/articles/intermodulation.htm#s4 And Distortion Measurement System https://sound-au.com/project232.htm One can get by with a less then stellar USB AF device. Some well respected AF amplifiers show some surprising weaknesses when tested this way.

Hello, I have built a system shown below by the attached article.Its a frequency locked loop. basicky I am using a YIG as VCO to tune it exactly to the cavity resonator. The phase and amplitude of the resonance shown below. The mixer acts as a frequency discriminator by the behavior in photo 3. So if we input a tone at some frequency and look what IF (error voltage) we get at point B as shown in photo 4 and 5 . The main problem I have is the YIG VCO. The YIG has two coils which we tune. A large coil call "tune" and a small coil called FM. The large "tune" coil is being fed near the resonance area,while the smaller FM coil is the coil I use to tune the error of the mixer IF (frequency discriminator) which compares the signal coming from the cavity resonator and the signal coming from the YIG. The second coil is FM coil: 1.5uH inductance and 1Ohm resistance FM coil. sensitivity 400Khz/mA The main problem is that I am tuning the error using the FM coil while the tune coil (which is biased by constant voltage) is not in the feedback fixing mechanism I only have the FM coil to compensate for the gap between the YIG and cavity signals. I was told to use a PI controller(between the IF output and YIG input )to compensate fro the tune drifting. Is there some strategy on how what parameters the PI controller should have to compensate for the exteral frequency drifting caused by the tune coil? Thanks. /g/electronics101/files/john233/High_spectral_purity_microwave_oscillator_design_using_conventional_air-dielectric_cavity%20%284%29.pdf /g/electronics101/photo/296358/3871687?p=Created%2C%2C%2C20%2C2%2C0%2C0 /g/electronics101/photo/296358/3871686?p=Created%2C%2C%2C20%2C2%2C0%2C0 /g/electronics101/photo/296358/3871685?p=Created%2C%2C%2C20%2C2%2C0%2C0 /g/electronics101/photo/296358/3871684?p=Created%2C%2C%2C20%2C2%2C0%2C0 /g/electronics101/photo/296358/3871683?p=Created%2C%2C%2C20%2C2%2C0%2C0 /g/electronics101/photo/296358/3871682?p=Created%2C%2C%2C20%2C2%2C0%2C0

Been playing with various chinese-originated latching relay solutions from Amazon. Most are 'overly optimistic' about capabilities. Very 'overly optimistic'. Otherwise the rest have issues operating in environment with heavy canbus, Bluetooth, pwm alternator, 2M xceiver, and brushed engine / HVAC fans. Reaching way back in my mind, I seem to remember JK flip flops toggling output when strobed if J&K are tied high. Maybe it wasn't JK, but another type? Important points being that outputs are low upon turn on, and stroking with momentary (debounced) switch (high input). I am thinking that can tie outputs to darlington driver array, like ULN2803 or similar. Up to 1/2A current, 50vdc max, designed for inductive loads. Haven't found any information on temperature control yet. Not sure if I am reinventing the wheel. I do know that relays / contractors that utilize magnets for latch hold are probitive physically and way overkill. Incidentally, relay outputs will be controlling multiple isolated power supplies. Need around 16ch of mixed outputs. Suggestions or alternatives if I am on wrong path? Tomorrow I will be trying to find 32/64 bit versions of LTSpice (or similar) as my 486DX4 based PC (500MB drive and 8MB Ram!) 16/32bit machine died during Hurricane Beryl. ~SD

Hello,I have the following old mixer called TXF-18075 which I want to test for saturation and power levels in down converting mode. I dont have any datasheet only this brief table I found.Unlike amplifier A mixer needs two input powers the RF and LO. How can I see In my lab two things: 1.What is the needed LO power? 2. How can I see mixer saturation using lab equipment? Thanks. /g/electronics101/photo/296358/3870599?p=Created%2C%2C%2C20%2C2%2C0%2C0

Hello: I am Ken Gordon, am now 82 years old, and have been involved in electronics since I was 13 years old in 1956. So, recently I have been involved in "Elmer-ing" a good friend who is not particularly adept at electronics. I have been helping him get his ham station operable on digital modes. He bought a new Acer laptop to use for these modes. While trying to get Fldigi installed, we discovered that his Acer laptop's USB ports' two data lines are reversed from all others we have dealt with up to this time: i.e. Data - (minus) and Data + (plus) are "reversed" in his new machine. This, apparenty, doesn't matter when those lines are used for USB devices such as a mouse or a USB powered CD drive, but that DOES matter when those data lines are used to pass audio to/from the computer to the digital interface (in this case either a SignaLink or a DRA device). I thought it might be easiest for me to make him a short jumper cable out of a short USB extension cable by cutting it, and "cross-wiring" those two data lines. However, upon opening the cable, I find not 4 (or 5) wires, but a total of 11, 3 of which are obviously grounds. I have not yet been able to "ohm-out" the wires vs connections since I must make a needle-point adapter for my VOM, but in the meantime, here are the wire colors. First, separate black, white, green and red. These should be the standard + and - 5 V and Data + and Data - But there are two "bundles" of other wires, These "bundles" contain a slim bare wire and two other thinner wires, pink and purple in one "bundle" and blue and yellow in the other. Might anyone here have a clue as to what these are, or how they are wired? Ken Gordon W7EKB Virus-free.www.avast.com

This is only relevant for this group because we deal with science, or at least I assume the study and practice of electronics is scientific. A friend suggested this book and I just finished it....I'll avoid any rants about how the left needs to get a clue. Higher Superstition: The Academic Left and Its Quarrels with Science Read it and cringe..... To me a pound is a pound, a kilogram a kilogram, numerals go from 1 to as high as you want to count, social repression has nothing to do with any of the proceeding. Note, I don't especially like the metric system but I accept it is real and valid. It is worth noting the book was written in 1994, well before the current social conflict over woke, social justice, DEI, et al. To me a business exists to make money, Proctor and Gamble's Gillette's "We Believe" ad campaign credited with causing a $5 billion dollar loss. I'd be a little upset if I were a stockholder... [For those who require proof, do a net search or https://pguru12.medium.com/procter-gamble-three-year-after-gillettes-we-believe-ffa9c82d9772 "A major development was reported between late July and early August, when it was announced that Gillette had lost $5 billion in quarterly sales, resulting in P&G giving Gillette an $8 billion non-cash writedown in terms of valuation." Or look into Bud Lite....and what a debacle.] "Go woke, go broke." [I believe John Ringo, SF author, came up with that witicism.] A society that turns it's back on science or uses social criteria to decide scientific truths is in deep trouble. I'm reminded of the Indiana Pi Bill, look it up on wiki and laugh, then look at the current social situation. I bet it'd pass today. I actually heard an English professor in college complain that "Pi should be rational, it just isn't right....makes no sense." I kept my mouth shut because as an EE major I was alread on thin ice for studying something real. <you had to be there> Hum, reality isn't right or wrong, but it is real. [and yea Quantum Mechanics gives me a stomach ache, but it's real...for various versions of real.] If you can't remember 3.1415, maybe you shouldn't teach or vote. [If you only have a 4 banger calculator, a very close approximation to Pi can be found with 355/113. Give it a try...] [A friend used Pi to 25 places, backwards, as her master password to the Big Iron in college. Yea I know some odd people.] We have the most advanced civilization in the history of the planet, people in third world nations enjoy cell phones, computers and instant communication. One might expect this to lead to an appreciation of science. [When I see the ISIS or Starlink satellites I'm filled with wonder that we've come so far so fast. I remember John Glenn atop that rocket...poor BW TV in school.] I wonder how long before they start burning us at stake for being heretics in the current social structure because we believe 1 and 1 are 2, not the result of some inherent racial paradigm. [My wife read this, "Oh don't be silly, they won't burn you at the stake, they'll simply send you to a special camp to be reeducated.] I just heard a rant on the radio about the inherent racism in math which lead me to write this....I wanted to call in and as "so which numeral is an oppressed minority?" But decided against it as trying to convert a rock to life by lecturing it. Or get our cat to not twine between my legs as I try not to trip over her. Both tasks are futile.

I normally type in a special font for dyslexics, Dyslexie. I can go to character map and snag Greek letters and other symbols, like those used in math, but it is a royal pain while typing. For serious writing, I place {} around the normal ASCII English letter and then I'll go back and replace them after I finish, in TV we called it "We'll fix it in post." I find trying to engage number lock and press alt while trying to remember what key to press for what Greek letter I want to be a bit too confusing, of course I could make a cheat sheet, that I'd have to keep track of.

Hello,I have built a PI controller I have its time domain step responce and AC responce. PI controller is supposed to help with the DC part of the error signal of a PLL system. I cant undertnad how,Is there away i could see it? /g/electronics101/photo/296358/3866087?p=Created%2C%2C%2C20%2C2%2C0%2C0 /g/electronics101/photo/296358/3866088?p=Created%2C%2C%2C20%2C2%2C0%2C0 /g/electronics101/photo/296358/3865523?p=Created%2C%2C%2C20%2C2%2C0%2C0 /g/electronics101/photo/296358/3866089?p=Created%2C%2C%2C20%2C2%2C0%2C0 Thanks.

A company that offeres every RF connector in the universe, if they don't have it, it doesn't exist. I've been collecting RF adaptors since my first hamfest, 1966, and, we used an ungodly mess to adapt his odd equipment. He found Brache Manufacutring LLC Newport Beach California. Their catalog has connectors I've never seen! And that's saying something! Their prices are reasonable considering the oddity of some connectors and if the quality of the adaptor my friend received is any indication, they are a first class company. Note: I have nothing to do with Brache other then as an amazed neutral observer. Another company I have dealt with is Pasternak, they have a lot of microwave connectors and other components such as RF relays, but nothing near the number Brache has. Pasternak's products are also first class. Note: I have nothing to do with Pasternak other then as a satisfied customer.

Does anyone have any idea how difficult it is to arrange a circuit to apply power to a DUT (Device Under Test) only at peak voltage? On both halfs of the 60Hz waveform? It is an imperial PITA on steroids! I went with a NE555 triggered at the zero crossing point and timed half way from that point for peak voltage. Simple zero crossing pulse generator to start the NE555 cycle. https://sound-au.com/appnotes/an005-f1.gif I used a 4N27, the output transistor drove another transistor, Darlington configuration. This drove a 600V 6Amp Triac by Teccor Part# Q6006F52. I used a 300 ohm 100 watt resistor (I have all sorts of odd stuff) as the load to insure the TRIAC would turn on and off. The turn on and off was OK but the timing was anything but OK. The output drifted around the peak but never was remotely stable. I was ready to give up when a friend said "Terry just use a 2 wire light dimmer module, they'll let you set for peak and hold it. My friend brought over several Hubble dimmer and, after some rewiring, I have a peak current turn on power supply. Note: Use a dimmer with dual RC network for increased stability. Now tomorrow or Sunday or Monday or someday really soon now I'll check the peak current through a 0.5uF capacitor. Now the real question, will a Siglent SDS 1202X-E capture the transients as the capacitor charges from the rapid delta-V? [Damn I wish this font had Greek characters!]

There have been several comments on high voltage measurements and probes buried in various messages. While fixing my microwave, I needed to measure the high voltage output from the transformer. As many have mentioned, a regular DVM cannot be used at that high voltage. I have a 1000 to 1 high voltage oscilloscope probe, but it is designed for a 1MΩ load, not the 10MΩ of the DVM. Adding a 1.11MΩ resistor across the input to the DVM compensated for the input resistance. I double checked measuring the 120AC. The transformer output was 2,380VAC . As usual do not do it if you really do not know what to do. It was a bad high voltage capacitor. Surprisingly, the very detailed service manual had a surprising error: It described testing the high voltage diode in forward and reverse with a regular DMM using the diode test mode. It will read open both ways since the forward diode drop is typically 8V because of the stacked diodes. Bertho

The following items have been added to the Files area of the [email protected] group. /Bertho's Folder/Sync Pulse R0.pdf /Bertho's Folder/Sync Waveform.png By: Bertho <boman33@...> Description: Line sync pulse Generator

Been kicking around idea of getting a pc based o-scope to keep in my tool box. My first ever was one that connected to a SoundBlaster Pro sound card. Have had a few over the years (portable pc based). Came across this apparent jewel at Amazon. To my eye, looks like a winner. Amazon Share-Link, nothing nefarious beyond screwing up your looked at history. https://a.co/d/10yH0lr Thoughts? SD

My wife's an RN. I had to ask her "Whats a nebulizer," and, follow up, "Is that something people carry with them to use in a car?" I had imagined the 'inhalers' asthmatics employ to help them breathe. She recalled that a Nebulizer was a machine unlikely to be employed while driving about in a rental car. So I went online and found the instructions for use: How to Use a Nebulizer: Prepare the medication: Follow the instructions provided by your healthcare provider to mix the medication with saline solution. Assemble the nebulizer: Connect the medication cup, tubing, and mouthpiece or mask to the nebulizer unit. Plug in the power source: If the nebulizer is electric, connect it to a power outlet. Start the nebulizer: Turn on the device to create a mist. Inhale the mist: Sit comfortably and breathe deeply through the mouthpiece or mask. Continue until all medication is gone: The treatment typically takes 5-15 minutes. Clean and store: Disassemble the nebulizer, clean it thoroughly, and store it according to the manufacturer's instructions. Are you sure you weren't using s Hookah? -- G.T.

"Their cars monitor and record conversations, video, one company even claims the right to collect DNA." As responsible adults, given the current lack of 'Truthiness,' I think it is incumbent upon the author to include a link to the "reliable source(s)" for his assertion - esp the bit about DNA. As to the hacking comment "I wonder how long before someone hacks into a car and shuts it down . . . " I do believe that has been demonstrated some years ago - but a link wouldn't be out of the question. In the alternative, revise the claims by adding a couple of words - maybe a preface of "I believe" to the " one company even claims the right to collect DNA." As in "I don't believe immigrants in Ohio were "eating the cats, eating the dogs, eating the pets of the people that lived there." Further, it would be great if an Electronics Focused Group was able to divine and publish hacks that would allow owners to disable this feature or that much as 'the community' has discovered ways to disable (reprogram) this annoying key or that on my Windows Laptop. One of our vehicles had the ability to send location data to the dealer/company application whenever I pressed the "PANIC" button. Something I did a few times when I forgot what the aisle I'd left the thing in looked like from the perspective of the store I'd, just moments ago, gone into. Sometimes, after I park, the cars around mine move about while I'm in the store - maddening! There oughta be a law! -- G.T.

This is kinda interesting: https://phys.org/news/2024-02-altermagnetism-magnetism-broad-implications-technology.html#google_vignette Might kick tech up a notch or two... -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, a critter that can be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin

Andy, I may have missed a couple of other observations but I would like to mention: 1) In situations with a lot of old fashioned 1/2 wave rectifiers or SCR voltage controls (arc furnaces, electroplating controls, certain PCs and the like) or in particular, simple light dimmers, there is a DC unbalance reflected back to the line transformer source. Line power transformers are likely to be running near saturation (it's an economic design choice.) The transformer is now non-linear and harmonic mixing will take place. This effect even shows up in big substation links from ground currents such as Schumann resonances generating modulation side bands. Another example. I went to a customer site for a problem with our equipment. They had racks of PCs being turned and off for the start and finish of test sequences. The surge of too many adjacent test PCs simultaneously coming on coupled with too small wiring, led to PC power supply glitches affecting the test as each test start required the charging of the electrolytic capacitors in the step down power supplies. A couple of cycles, but more than enough to cause trouble. The turning-on PCs ignored the glitch as they have have delay circuits built in and ignore their own disruptive effect, but already ON PCs were not happy. Thinking back about the past, mercury vapor rectifiers were often in 1/2 wave configurations -- too expensive to wire up full wave rectifiers -- a 4:1 cost. Your linear accelerator may have had a similar problem, needs for a lot of power on a pulse basis. It may even have been synchronized to the line as I believe some are to minimize line noise from data capture, Regards, Charles Patton