Build a guitar tuner - Page 1
Forum section: electronics / projects

author: Guitar42
author_rank: Contributor
timestamp: January 22, 2021, 11:53:47 pm
content: I'm way over my head here, but I'm looking to build a small guitar tuner circuit. I know there are a million cheap tuners out there that work great, but I have my reasons. Unfortunately I don't know where to begin. I'm looking for something fast, but as low a part count as possible. Anyone have any thoughts?

author: Benta
author_rank: Super Contributor
timestamp: January 22, 2021, 11:56:05 pm
content: Tuning fork?

author: gnuarm
author_rank: Super Contributor
timestamp: January 23, 2021, 01:40:02 am
content: Many years ago I wanted to do this for myself because tuners were much more expensive. With the available components it was not easy and I gave up. Looking at it more recently I think there are many more ways to do this using digital signal processing (DSP). If you don't know where to begin, DSP will be a long, hard road to travel though. However, there may be analog techniques.To start with, how accurate do you need it to be? Typical tuners provide a ±50 cent range with resolution to about 1 cent. Do you want to just tune guitars or be more flexible? I ask this because if you only want to tune the six strings on a conventional guitar that can be done with six circuits of one note each. With more notes you likely will want a circuit that finds the closest note and tunes to that.I would love to know how the inexpensive circuits do it.

author: retiredfeline
author_rank: Frequent Contributor
timestamp: January 23, 2021, 01:51:53 am
content: Why not use a smartphone app unless you like building?

author: JohnnyMalaria
author_rank: Super Contributor
timestamp: January 23, 2021, 02:00:31 am
content: https://www.instructables.com/Arduino-Guitar-Tuner/

author: Teledog
author_rank: Regular Contributor
timestamp: January 23, 2021, 05:20:00 am
content: Been doing that since the 80's.Building/repairing old 7 segment display & other tuners.Lots of time & money for a so-so outcome.The red "Snark" tuners are my "go-to" units now..guitars(reso), banjo, mandolin, sitar, etc..They DO tend to eat CR2032s though..

author: MIS42N
author_rank: Frequent Contributor
timestamp: January 23, 2021, 09:10:43 am
content: IMO the simplest way would be to make a circuit that generates the frequencies you want, put them into some sort of amplifier, tune to the note. A while back I wrote code for a top octave generator running on a ATmega328P @ 16MHz. Something likehttps://www.ebay.com.au/itm/Mini-USB-CH340G-Nano-V3-0-ATmega328-5V-16MHz-Micro-Controller-Driver-For-Arduino/264368325445It simultaneously output the following frequencies on different pads:; note frequency(Hz) Output; C9 8368.2 D2 (PD2); B8 7905.1 D3 (PD3); A#8 7462.7 D4 (PD4); A8 7042.3 D5 (PD5); G#8 6644.5 D6 (PD6); G8 6269.6 D7 (PD7); F#8 5917.2 D14 (PC0); F8 5586.6 D15 (PC1); E8 5277.0 D16 (PC2); D#8 4975.1 D17 (PC3); D8 4694.8 D18 (PC4); C#8 4434.6 D19 (PC5)To hear the note I had a resistor divider that went to the line in of an old boom box (the signal from the uP is 5V, overloaded the input). Touch the right pad and hear the note. The notes are way to high for guitar pitch, but a program to do something similar at guitar frequencies would work. Not as convenient as a proper tuner but for very little money and some programming it's simple.

author: rs20
author_rank: Super Contributor
timestamp: January 23, 2021, 09:41:06 am
content: I did something like this (not exactly guitar tuning, but a different frequency detection) way back with an Arduino-equivalent -- the basic steps were as follows (half recollection, half redesigning from scratch):Microphone -> ADC pinSampled at 8KHz or somethingEach sample was multiplied by cis(omega * t), and added to a (complex-valued) accumulatorTake the argument of the complex value out of the accumulator (resetting it to zero in the process) every 100 samples or so, putting it in an arrayThen inspect the values in the resulting array:If the principal tone being heard by the microphone matches the desired frequency (omega = 2 * pi * frequency), then the values in the resulting array will have no overall upwards or downwards trend.If it's higher than the desired, the values will steadily decreaseIf it's lower than the desired, the values will steadily increaseTones far away from the desired frequency will get mostly averaged away in the accumulators, leading to little wiggles in the value, but no overall upwards or downwards trend.So you just detect the direction/rate that those values change (keeping in mind that they'll wrap around from -pi to pi), and display it as a "sharp / good / flat" indicator/scale.To tune a different string, just change omega (or, as a fun hack, change the sampling rate instead!).(The underlying principle is similar those spinning strobe-light based things that let you check the speed your vinyl disc record player was playing at, except all done digitally of course.)The nice thing about this is that it's much much cheaper than FFT, easily doable on an Arduino IIRC. Obviously the sensitivity to background noise won't be great compared to a full on DSP/FFT approach, but I'd be surprised if it wasn't highly useful. Just making a device that emits a tone and demanding that the user sync up the frequencies manually seems kinda boring to be, but YMMV of course.PS/ cis(x) = cos x + i sin x

author: Renate
author_rank: Super Contributor
timestamp: January 23, 2021, 03:14:31 pm
content: Quote from: Teledog on January 23, 2021, 05:20:00 amMine doesn't.https://www.eevblog.com/forum/projects/not-too-bright-guitar-tuners-(snark)/msg3348774/

author: Distinctly Average
author_rank: Contributor
timestamp: January 23, 2021, 04:42:25 pm
content: I made one for fun with a raspberry pi during lockdown as I was bored. I did it in python using the script herehttps://www.chciken.com/digital/signal/processing/2020/05/13/guitar-tuner.htmlI did it with a Pi4 but I reckon it could also be done with the new £4 Pi Pico -https://www.raspberrypi.org/products/raspberry-pi-pico/. Looks like an amazing little bit of hardware for the price.

author: CaptDon
author_rank: Super Contributor
timestamp: January 25, 2021, 04:05:37 am
content: What is it you want to create? When there are a thousand different wheels out there why re-invent the wheel?Do you want yours to be smaller? Lighter? Fancier? Solar Powered? You want to make one, why?? Give us at least some idea of what is special about yours?? I use a hand held korg unit and when playing out I have a korg dtr-2 in my floor rack which I can see from 20 feet away and can tune on-the-fly. Starting off way-over-your-head is a short road to disaster. Do you have even the basic soldering tools, digital multimeter, oscilloscope or any other diagnostic tools to test your design when the magic smoke rolls out?

author: james_s
author_rank: Super Contributor
timestamp: January 25, 2021, 05:07:53 am
content: Have you tried searching google for "DIY guitar tuner"? That's where I'd start, seems like the sort of thing multiple people would have built already.

author: ledtester
author_rank: Super Contributor
timestamp: January 25, 2021, 06:16:08 am
content: There are a bunch of guitar tuner projects based on an AVR microcontroller.I think it all started with...- Jesper Hansen's gtuner (2001)(written for a at90s2323 but easily ported to a modern Atmel processor)http://web.archive.org/web/20150625074143/http://www.myplace.nu/avr/gtuner/index.htm- "Guitar Tuner v1.2" (2003)https://community.atmel.com/projects/guitar-tuner-v12- "Stimmmopped" (2008)https://github.com/das-labor/Stimmmopped- An attiny45 version of gtuner (2010)https://www.mikrocontroller.net/topic/162839Update:Here's a project from 1999 using an at90s8535. Has a good description of the theory behind its operation:http://web.archive.org/web/20010515192629/http://instruct1.cit.cornell.edu/courses/ee476/FinalProjects/s1999/berman/project.html

author: BradC
author_rank: Super Contributor
timestamp: January 25, 2021, 07:24:25 am
content: I like stroboscopic tuners.I used a Parallax propeller to estimate the incoming note by looking at the period between zero crosses, rounded that to output a precise clock which drove a 64 bit shift register with leds on it. I then used a simple data-slicer (zero crossing detector) on an op-amp to drive the common of all the LEDS.Play a note and as long as it's vaguely close it locks on and you see the waveform moving on the leds. Tune to stop it moving. If it picks up a harmonic by mistake it's still doing the right thing.

author: Guitar42
author_rank: Contributor
timestamp: January 25, 2021, 03:36:09 pm
content: Mine is embedded in a guitar. It's something I've been doing for years, but the product I've been using (modifying) won't be available for much longer. I've been buying a custom IC that does all the work, but the guy I've been buying from has retired and I'm trying to decide if I should purchase his chip inventory and kick my problems down the road a bit or just figure out how to make the entire product in-house. I've been building guitars for almost 25 years and effects for 12. I have a fair amount of Arduino experience and a limited amount of Atmel Assembler experience, though I cringe at the thought of doing that again. The product I've been using is similar to the old Sabine tuners.

author: Guitar42
author_rank: Contributor
timestamp: January 25, 2021, 03:43:15 pm
content: I will check these out this week when I have a minute. I've looked at a few Aduino based tuners in the past, but it was several years ago at least. I also found a company that produces a tuner IC, but it's a bit on the expensive side and isn't quite the interface that I want to use.

author: james_s
author_rank: Super Contributor
timestamp: January 25, 2021, 06:26:24 pm
content: Quote from: Guitar42 on January 25, 2021, 03:36:09 pmI don't think many people use assembler anymore for this sort of thing. In most cases an embedded project like this would be done in C. The Arduino is very similar to C but it does take some effort to transition.

author: MIS42N
author_rank: Frequent Contributor
timestamp: January 27, 2021, 09:01:03 am
content: Quote from: james_s on January 25, 2021, 06:26:24 pmI write assembler and nothing else. [well, maybe a bit of BASIC to test algorithms before writing them in assembler]. I mentioned the top octave generator a few posts back, written in assembler. There was a 'competition' on Hackaday, the best anyone managed using C with some assembler IRC was half the frequencies, some generated by onboard using the PWM modules and running a 20MHz clock. I came late to the conversation, did the full speed job entirely in software with a stock 16MHz clock. That is the difference between assembler and C.I don't think my current project (a GPSDO) could be written in C. It has an IRC running at 40kHz, a software UART receiver running at 9600 baud, a detector that times a pulse arrival to within 25nS, hardware UART also at 9600 baud (I needed to collect 2 serial inputs and the uP has only 1 UART). It has two background tasks running, one to interpret one serial stream and the other to do do calculations. All this on a $2 uP (PIC16F1455) with a 10MHz clock. Yes, I could use some much more expensive chip and hope the C can deal with the timing constraints. But my experience with C for uP is you need to know all the details of the uP anyway, and badly documented C is harder to deal with than well documented assembler.The big advantage of C is maintenance. There are few assembler programmers and each processor line has its own set of instructions. So finding someone to take over an existing assembler program is difficult. I don't have the problem as I'm working on personal projects for fun.

author: jmelson
author_rank: Super Contributor
timestamp: January 27, 2021, 04:19:37 pm
content: Years ago, there used to be a chip called a "top octave generator". You hooked it to a quartz crystal, and it produced all the notes for an octave. They were used in electronic organs. Then, you put a string of divide by two FFs after that, and tap off the octave you want.The divider string is fed by a 12-position switch for the specific note you want. it can be done with 3 chips, the top octave, a CMOS 4020and an audio amplifier chip.Jon

author: james_s
author_rank: Super Contributor
timestamp: January 27, 2021, 07:27:52 pm
content: Quote from: MIS42N on January 27, 2021, 09:01:03 amYou are the exception rather than the norm. There are of course still hobbyists who program in assembler and there are some rare professional projects that might have a little hand tuned assembly here and there but the VAST majority of modern embedded development is done in C. It's already possible to get quite close to the hardware in C, not to be confused with the slow and bloated (but reasonable for their intent) libraries that Arduino uses.You don't need a more expensive chip, you can get a 100MHz 32 bit ARM for under $2 that will absolutely blow away the old PIC16F and for not much more you can get even crazier speeds, multiple cores, etc. Not that there's anything wrong with using an old part for hobby projects, I'm still occasionally using ancient AT90S2313 AVRs because I got a good deal on a whole tube of them over 20 years ago. I don't use them for anything where I have to go to heroic lengths to squeeze out the necessary performance though.Anyway in a nutshell, there is no reason IMHO for a beginner today to learn assembly if they just want to build a working project. If one wants to gain a deeper understanding of how a microcontroller works then by all means give it a go.

author: james_s
author_rank: Super Contributor
timestamp: January 27, 2021, 07:29:09 pm
content: Quote from: jmelson on January 27, 2021, 04:19:37 pmI encountered those looking at the schematic for an old Heathkit musical doorbell. I ended up recreating a top octave generator in VHDL and playing around with it, I don't think anyone has made the dedicated ICs in years though.

author: jmelson
author_rank: Super Contributor
timestamp: January 28, 2021, 02:10:45 am
content: Quote from: james_s on January 27, 2021, 07:29:09 pmRight. I think you could easily build a one output at a time programmable divider with 4 input lines that would select the desired divider ratio, and put it in a relatively small CPLD. If you wanted the whole octave at once, it would take a larger chip.Jon

author: MIS42N
author_rank: Frequent Contributor
timestamp: January 28, 2021, 04:17:52 am
content: Quote from: james_s on January 27, 2021, 07:27:52 pmYou are right. But when one knows all the intricacies of a particular processor, it is hard to move to another. How to write to non-volatile memory, how to trigger a timer from an analog signal, how to run the PWM, order the interrupts etc. etc. Also, like you, having a stock of one part it is convenient to use them.I can't really comment on the value of learning assembler, I've been writing it for various architectures for a long time. For instance, ICL computers used a 6 bit character and wrote data to magnetic tape 4 characters to 3 8-bit frames. When work moved from ICL to DEC computers, they used 8-bit characters. It looked like we'd need to send our tapes off to be converted. Instead I wrote an operating system mod for the DEC that had a mount mode to make the ICL tapes look like DEC tapes. Assembler was fast enough to do it as the tape was being read.I like the challenge of getting more for less. I wrote a program in BASIC that given the time and date, your latitude and longitude, would tell you where to look in the sky for the various planets. It took less than 4Kbyte.I guess I'm just a dinosaur.

author: Renate
author_rank: Super Contributor
timestamp: January 28, 2021, 11:34:40 am
content: Quote from: MIS42N on January 28, 2021, 04:17:52 amRawr!It never hurts to know a bit of assembler (or smali, Android Dalvik instruction code).You may not know enough to write it but it helps to analyze, reverse engineer or just double check what your compiler has done.I write assembly still for odd-sized fixed point numerical routines.Still, with even crappy chips having floating point now...The trend is clear with Arduino and digitalWrite() instead of flipping a silly bit.Soon you'll be needing a 1 GHz processor just to blink an LED.

author: james_s
author_rank: Super Contributor
timestamp: January 28, 2021, 07:24:11 pm
content: Arduino is for beginners and hobbyists, it has its place, digitalWrite is crap but it works for what it's supposed to do. Plain old C is much lower level and much faster, there is nothing like digitalWrite, IO is normally done with bitwise operations.As I said, there's nothing wrong with learning assembly, I spent some time recently learning 6502 assembly which is even more archaic. It's not something I'd do if I just wanted to build some gadget though.

author: SiliconWizard
author_rank: Super Contributor
timestamp: January 28, 2021, 07:57:51 pm
content: Of course, Arduino is by no means an indication of where the embedded software industry is heading.That said, the trend with HALs is there. You have similar functions for setting IOs in most available HALs. Of course nobody is forcing you to use them, but Renate may not be completely wrong.https://en.wikipedia.org/wiki/Wirth%27s_lawPoint is, available resources unfortunately dictate how we use them. This is true in all areas of life. No need to note that this is especially true with how we use energy. We can afford to "waste" resources when they are plentiful.As small embedded targets become more powerful and with more integrated memory, we WILL waste those resources. Guaranteed.

author: Renate
author_rank: Super Contributor
timestamp: January 28, 2021, 08:19:05 pm
content: Well, yeah, there's a lot of things going on here.If you have to dev on a new processor and all you want is a stinking timer do you want to read 50 pages of registers or just call gimme_timer();There's also a lot of dependency hell. You want to use string::isEmpty() and it pulls in a JSON parsing library, an XML parsing library and SSL.All I can say is that a lot of time I see a utility that weighs 7 M and I can duplicate it in 70 k.I know, the current metrics says, "Who cares?"

author: james_s
author_rank: Super Contributor
timestamp: January 28, 2021, 09:51:05 pm
content: A lot of the new micocontrollers are fiendishly complex. It's one reason I've largely stuck with the 8 bit AVRs, I can make something work without spending a week studying a 300 page datasheet-novel.

author: MIS42N
author_rank: Frequent Contributor
timestamp: January 29, 2021, 03:43:21 am
content: Quote from: james_s on January 28, 2021, 07:24:11 pmThe old 6502, the heart of Apple II, VIC 20, C64 and even used as a graphics processor in a Visual 1050.One of my more bizarre assembler hacks was to get a C64 to interface to a 2400 baud modem bit bashing via the parallel port (no UART). The C64 was used as an interim bidding terminal for an online auction, we had quite a few deployed until others were able to get an IBM PC (8086 based?) to do the job. The users didn't like the monochrome PC screen after using the colorful C64 but were appeased by being gifted the C64 to take home to their kids.

author: Renate
author_rank: Super Contributor
timestamp: January 29, 2021, 12:02:20 pm
content: Quote from: james_s on January 28, 2021, 09:51:05 pm300 pages? Ha, that's a pamphlet, not a novel.The NXP "i.MX RT1060 Processor Reference Manual" is 3637 pages.(Even the Atmel ATmega328P "datasheet" is 660 pages.)

author: gnuarm
author_rank: Super Contributor
timestamp: January 29, 2021, 08:03:02 pm
content: Quote from: BradC on January 25, 2021, 07:24:25 amI have a stroboscopic tuner. It is shaped like a pick with a red and a green LED on either side near the point. The two LEDs are 180° out of phase so it shows the same string at two points on the accurate pitch waveform. In tune the two illuminated parts of the string don't move. High or low and they move away and back. It doesn't tell you + or - but that's easy to get once you start to adjust. It has a thumb wheel to select the string. Not bad. It doesn't help me play any better though.

author: gnuarm
author_rank: Super Contributor
timestamp: January 29, 2021, 08:11:10 pm
content: Quote from: james_s on January 27, 2021, 07:29:09 pmWonder how they generate the top octave and how accurate the notes are? I can't think of a way to do that without a PLL or something messy. If I were doing that in an FPGA I would use an NCO to set the frequency to whatever accuracy I desire.Oh, wait! I HAVE done that. It's part of a design for the alarm sounds on a ventilator at this moment. They use music notes in patterns rather than klaxon horns. Don't want to alarm the patients! I think I set it up to be integral on Hz and the fractions are binary. 33.554432 MHz is actually a frequency you can buy in a vendor programmed silicon oscillator now. They seem to be taking over from quartz.

author: oPossum
author_rank: Super Contributor
timestamp: January 29, 2021, 11:45:20 pm
content: Quote from: gnuarm on January 29, 2021, 08:11:10 pmJust integer dividers.

author: oPossum
author_rank: Super Contributor
timestamp: January 30, 2021, 12:38:57 am
content: Some error calculations...https://docs.google.com/spreadsheets/d/1cI3i9CDXdeVyEMNwWbgRs_peHhN3C9gLFOwNf4j2Ju0/edit?usp=sharing

author: rs20
author_rank: Super Contributor
timestamp: January 30, 2021, 06:33:31 am
content: For fun, I thought I'd try redesigning the integer dividers from scratch, to see if I'd come to the same conclusion as the MK50242 designers. It turns out that the set of integer divider values that that chip uses:239 253 268 284 301 319 338 358 379 402 426 451...running at 2.000240 MHz as specified in the datasheet is a conspicuous outlier in terms of just how good the approximation is:And just for bonus marks, the clock frequency being so close to 2 MHz (easily within crystal pulling range) seems like a delightful cosmic coincidence!Other, even better (albeit higher frequency) outliers:2.923018 MHz / [349 370 392 415 440 466 494 523 554 587 622 659] Error: ±0.840 cents4.251793 MHz / [508 538 570 604 640 678 718 761 806 854 905 959] Error: ±0.528 centsOf course, if you start with 16 MHz (or even 2 MHz?) and use 16-bit dividers to jump right down to C4/C5 instead of C♯8/C8, then you'll get much better accuracy than any of the special cases listed above.

author: oPossum
author_rank: Super Contributor
timestamp: January 30, 2021, 07:30:01 am
content: National also made the MM5555/MM5556 chips that use a 2.12608 MHz clock. I have updated my spreadsheet to include them.https://docs.google.com/spreadsheets/d/1cI3i9CDXdeVyEMNwWbgRs_peHhN3C9gLFOwNf4j2Ju0/edit?usp=sharinghttp://www.bitsavers.org/components/national/_dataBooks/1977_National_MOS_LSI_Databook.pdf(Chapter 3)Edit: 2.12608 is very close to half of 4.251793 and the MM5556 has three divisors that use both clock edges (380.5, 452.5, 479.5)

author: Renate
author_rank: Super Contributor
timestamp: January 30, 2021, 12:11:48 pm
content: On the repair forum somebody was working on a Peterson Model 420 strobe tuner.It uses a AMI S50241 top octave generator, which uses the same 9 bit dividers as above.But you can see from the schematics that the Peterson switches in resistors to tweak the main LC oscillator for the notes that are off the furthest.See switch S1B (schematic is showing older two chip solution).https://www.eevblog.com/forum/repair/peterson-model-420-strobe-tuner-repair/msg3378050/#msg3378050

author: oPossum
author_rank: Super Contributor
timestamp: January 31, 2021, 01:18:17 am
content: The Hammond organ does quite well using a mains synchronous motor and gears.

author: ledtester
author_rank: Super Contributor
timestamp: February 16, 2021, 10:02:52 am
content: This Instructable explains how to use autocorrelation to determine frequency and how it differs from time-domain techniques. Contains example code and a link to a Arduino guitar tuner sketch:https://www.instructables.com/Reliable-Frequency-Detection-Using-DSP-Techniques/

author: mikerj
author_rank: Super Contributor
timestamp: July 25, 2022, 09:19:54 am
content: Quote from: DarySixsan on July 25, 2022, 08:59:08 amDid you really sign up just to post that? What "special parts" do you think are required?

author: Halcyon
author_rank: Unknown
timestamp: July 25, 2022, 10:02:51 am
content: Quote from: mikerj on July 25, 2022, 09:19:54 amHmmm... Does anyone else smell pork?

author: eugene
author_rank: Frequent Contributor
timestamp: July 25, 2022, 04:49:25 pm
content: Quote from: DarySixsan on July 25, 2022, 08:59:08 amOne of the least useful posts ever, that's not even considering that the thread is 18 months old. We should have an award...Quote from: Halcyon on July 25, 2022, 10:02:51 amYou think he might be a cop?

author: themadhippy
author_rank: Super Contributor
timestamp: July 25, 2022, 05:54:01 pm
content: QuoteMore likely SPice hAM

author: magic
author_rank: Super Contributor
timestamp: July 25, 2022, 09:27:45 pm
content: If there is a pic of a woman in the avatar, it's a spammer. Every time.

author: ledtester
author_rank: Super Contributor
timestamp: July 26, 2022, 03:40:06 am
content: Quote from: magic on July 25, 2022, 09:27:45 pmThe URL of the user's pic is:https://www.eevblog.com/forum/avatars/Musicians/Christina_Aguilera.jpg

author: ebastler
author_rank: Super Contributor
timestamp: July 26, 2022, 07:12:07 pm
content: Quote from: Halcyon on July 25, 2022, 10:02:51 amObviously; all the spammer hallmarks are there: First-time poster, digs up an old thread, adds a meaningless comment, needs only a few minutes between registration and "last time seen".Do you prefer to make a note and check back after they add their spam link? Why not kill the account right away?

author: themadhippy
author_rank: Super Contributor
timestamp: August 01, 2022, 03:44:20 pm
content: QuoteAnd those specialist parts are?

author: TimFox
author_rank: Super Contributor
timestamp: August 01, 2022, 04:06:40 pm
content: By the way, the integer ratios used in the examples above give reasonable approximations to equal-tempered scales, based on half-step = 21/12, which are needed with keyboard instruments (starting with harpsichords in the time of Bach).For stringed instruments, you may want "just intonation", which have simpler integer ratios. When tuning in equal temperament, the fifth is flat (1.49831:1) compared to the "just" ratio of 3/2.Seehttps://pages.mtu.edu/~suits/scales.html

author: ebastler
author_rank: Super Contributor
timestamp: August 01, 2022, 06:11:01 pm
content: Quote from: themadhippy on August 01, 2022, 03:44:20 pmHalf a pound of the finest spam, with links added to taste.Can't believe that link spammer is back in the same thread, with more or less an identically worded post. See the quoted post from "DarySixsan" above, which has since been deleted.

author: gnif
author_rank: Unknown
timestamp: August 02, 2022, 12:19:22 am
content: Quote from: ebastler on August 01, 2022, 06:11:01 pmWaiting to pounce on this when it's edited with links. I am trying to make the company that is using this scummy SEO operation aware of what these tools are doing.

author: MIS42N
author_rank: Frequent Contributor
timestamp: August 02, 2022, 02:35:48 am
content: Source code for a top octave generator using an AtMega328P.www.cashin.net/TopOctave.asm

author: gnif
author_rank: Unknown
timestamp: August 06, 2022, 01:04:36 am
content: Quote from: gnif on August 02, 2022, 12:19:22 amJust an update on this, the shop owner got in touch, apologised and stated they have terminated their SEO contract with the company that was performing this.

author: ebastler
author_rank: Super Contributor
timestamp: August 06, 2022, 06:58:06 am
content: Quote from: gnif on August 06, 2022, 01:04:36 amIt's a lot of effort for you to contact the companies being advertised -- but if you do this a few more times, maybe the SEO vendor will figure out why they are losing contracts. And while I doubt that this will stop them from using forum spam as one of their "optimization" means, they might instruct their crowdsourced spam agents to leave the EEVblog forum alone.(Ask the companies you contact to point out to the SEO vendor that it was the EEVblog forum which alerted them to the SEO's spam tactics. Assuming that only one or a few SEO services are behind the spam posts we get here, they should notice the pattern after losing a few more contracts.)

author: sam[PS]
author_rank: Contributor
timestamp: August 22, 2022, 02:44:56 pm
content: Wowww you all go way too complicated (or not enough ?) What you do you get a wheel with 4quadrants, 2 are opaque two are translucent. Then you make that weel turn at 1/2 the number of cycle/s than the frequency of your desired note. Then you place a led behind that wheel and command that led with your audio signal. And bim bob's your uncle, you get a strob tuner.As of how you precisely regulate the speed of the motor driving the wheel well i told you it might in fact be bit more complicated ;c)Of course you can do that digitally, but then it's just a boring convolutionJust my 2cts ...

author: Terry Bites
author_rank: Super Contributor
timestamp: August 22, 2022, 06:36:37 pm
content: What reasons?

author: gnuarm
author_rank: Super Contributor
timestamp: August 22, 2022, 08:25:59 pm
content: Quote from: sam on August 22, 2022, 02:44:56 pmSounds rather complex. I bought a strobe tuner that has a red and a green LED with a bit of a divider between them so they light adjacent parts of the string. Pluck the note and the LEDs flash on the string, one 180° out from the other. When out of tune you see the string moving in the strobe. Adjust it further out and it moves faster. Adjust closer to the right pitch and the vibration slows. When you get it right, the red and green bits of the string stand still with respect to each other.I guess the colors are not essential, but allow the motion of the string to be more visible.

author: Terry Bites
author_rank: Super Contributor
timestamp: August 23, 2022, 10:11:36 am
content: I reinvented the wheel once, my patent application was turned down. Corporate bullying again!