String pluck detector??

[RGP]

Trying with a different file extension

[RGP]

My file size was too large. JPG works. Here's the E&MM Harmony Gen. Clone

[RGP]

Hetrer's the pluck detector

[RGP]

Ops, more bad typing. Sorry. The images seem a bit blurry but legible. If there are any issues seen in these let me know so I can correct them

[RGP]

Now another question. On the Harmony Generator. Do I need to add some sort of buffer on the square wave output mixer to split it into two dedicated outputs? One for a square wave send and the second to a square to triangle converter.

[ElectricDruid]

Do I need to add some sort of buffer on the square wave output mixer to split it into two dedicated outputs?

If you mean the output marked "Square Send" then the answer's "No" because it's already coming directly out of an op-amp, and that op-amp can easily drive two inputs.

[RGP]

Thanks for clearing that up for me Tom. Did you see any errors with the schematics? 

[Ben N]

Hetrer's the pluck detector

What? The actual pluck?



I'll show myself out.

[PRR]

I found this (again), on an old and slow Chromebook, not sure it goes here, but someone will recall where we were talking digital counters to sine-step waves.
Google  digital_sinewaves_11_76
https://www.google.com/search?q=digital_sinewaves_11_76&rlz=1CAHKDC_enUS965&oq=digital_sinewaves_11_76
Find:
https://www.tinaja.com/glib/rad_elec/digital_sinewaves_11_76.pdf
Don Lancaster, {EDIT} so it is to the point and correct.

[Rob Strand]

Early patent for the conventional diode tapped sine shaper (1951/1956),
https://patents.google.com/patent/US2748278A/en?oq=+us2748278

Don Lancaster, so it is to the point and correct.

I like Don Lancaster's stuff but that article is full of errors.

In your second link check out the table and the 16x clock values.  He is using the 7-tap (vs 8-tap) version (in fact he uses the type which always has an unconnected tap; ie. zero filter weight).

Tell-tale signs something is wrong:
- The single value resistor tap is the high-valued resistor where it should be the lowest valued resistor.
- The resistors that are close in value are the high valued resistors instead of the low valued resistor.

The root cause is the ratios in parenthesis (and the formula) are for *conductances* not resistances.
16x clock, 7-tap: 
incorrect resistances: 22.1K; 41.2K; 53.6K; 57.6K; 53.6K; 41.2K; 22.1 K
conductance ratios: (1.000)(1.849)(2.412)(2.613)(2.413)(1 849)(1.000)
invert conductances to get resistance ratios
  (1.000)(0.5408)(0.4146)(0.3827)(0.4146)(0.5408)(1.000)

As a crossreference, the book Art of Electronics by Horowitz and Hill  gives a 16x clock example with 7 resistor taps  using a CMOS 4015 device.
The resistor values are:  57.6k, 30.9k, 23.7k, 22.1k, 23.7k, 30.9k, 57.6k

The resistance scale factor 1 corresponds to resistor value 57.6k,
corrected resistance scale factors: (1.000)(0.5408)(0.4146)(0.3827)
resistor values approx 57.6k time these: 31.2k, 23.9k, 22.0k

We can see the corrected calculations, based on conductance ratios, agrees with the Horowitz and Hill resistors,
within rounding to the nearest (funky) resistor values.

Exact values for 22.1k: 57.75k, 31.25k, 23.92k, 22.10k, 23.92k, 31.25k, 57.75k

There were other errors in the article.  I'm not even sure the formula produces the correct ratios, or that the example circuits have the correct resistor values.  I have gone over this subject at some point.

[RGP]

Thanks for the info. I'll need to study it. Do either of you see any errors or problems with the 3 schematics?  I'm still looking at the Elektor square to triangle wave converter. Unfortunately I can't find the text for that schematic.   

[RGP]

The point labeled as U2. What is it? Every PDF I found for 301 circuits doesn't include that circuit or it's related text.   

[Rob Strand]

Thanks for the info. I'll need to study it. Do either of you see any errors or problems with the 3 schematics? 

I got a security issue trying to look at the original PDF to compare it with.   Haven't looked at the cause. yet.

I'm still looking at the Elektor square to triangle wave converter. Unfortunately I can't find the text for that schematic.   

Elektor?  which one?   You mean the the circuit I posted here?

https://www.diystompboxes.com/smfforum/index.php?topic=55075.msg1268263#msg1268263

The point labeled as U2. What is it? Every PDF I found for 301 circuits doesn't include that circuit or it's related text.   

Still not sure what circuit you are referring to.  Which post did it appear?

[RGP]

Rob. It's posted here somewhere, but I'm attaching it anyway.

[RGP]

Rob. I have the pdf onmy thumb drive. Should I attach it here?   

[Rob Strand]

Rob. It's posted here somewhere, but I'm attaching it anyway.

Circuit from:  Elektor May 1978, p5-46 to p5-47

(Text translated from German Issue)
"Figure 3 shows a circuit that compensates for the decrease in amplitude with increasing frequency by increasing the charging voltage U2. The function of the short-circuit switch in FIG. 2 is performed here by transistor TI. Its collector-emitter path becomes conductive at the time of the positive edge of the square-wave input signal, so that capacitor C3 is bridged for a short time. On the falling edge of the input signal, T2 conducts; at this point, C4 is charging. The mean value of the current is proportional to the frequency of the input signal within a specific frequency range. So if the input frequency increases, the voltage at C4 also increases practically linearly. The result is an exponential sawtooth voltage with an amplitude in the range of 60 Hz. . . 10 kHz remains constant; however, the shape of the sawtooth still depends more or less on the frequency. This blemish (by the way, a linear sawtooth has less "musical content" than a sawtooth with an exponential rising edge) can be eliminated by replacing resistor R4 with a current mirror (T3/T4 in Figure 4). An output buffer (T5) completes the square-wave sawtooth converter ..."

I believe the idea is that as the frequency increases the DC level at U2 increases to compensate for the drop in level at the main output (the exponential sawtooth).   I have not checked how well this works.   That idea applies to both Fig 3 and Fig 4.

Rob. I have the pdf onmy thumb drive. Should I attach it here?

AFIK, can't attach PDF's or can only attach small ones.

[RGP]

Rob. Thanks for explaining the circuit to me. I'm leaning toward using it. Hope you can figure out why the pdf doesn't show up. I read Marcus' posts over many times to get the schematics right, or at least hope they are. Still wondering where the input signal is coming from and the filter he used. I'm thinking the AMS100's compressed output. Does that seem right to you?     

[Rob Strand]

Rob. Thanks for explaining the circuit to me. I'm leaning toward using it. Hope you can figure out why the pdf doesn't show up. I read Marcus' posts over many times to get the schematics right, or at least hope they are. Still wondering where the input signal is coming from and the filter he used. I'm thinking the AMS100's compressed output. Does that seem right to you?   

The PDF issue is just a limitation of the forum.  It stops people uploading crazy large files - which would probably clog-up the database.

Yes, the input comes from the AMS100.   I had to decipher what was going on there early on in the thread.

I made these short notes at the time.

"This project uses part of the AMS100 circuit from DEVICE magazine.
In particular the envelope extractor from part 1.

The schematic starts at the peak detector output. The buffer on the
schematic is a replica of the buffer on the AMS100.1 schematic.
The one after the peak detector.

On page 4 of the thread some mods are given."
[the thread is this thread.]

AMS-100 guitar processor
Appeared in DEVICE magazine

https://hammer.ampage.org/?sort=new&page=11
https://hammer.ampage.org/?sort=new&page=12

Issue 1 - part 1
https://hammer.ampage.org/files/Device1-1.PDF

The other parts of the AMS100 can be downloaded from there also - compliments of Mark Hammer.

[RGP]

Rob. I based all the schematics on that same criteria you pointed out. I have all the device issues & the E&MM Harmony Generator thanks to Mark Hammer having them on his site. I'm wondering if it's possible to use the 3rd & 5th intervals at the same time? The note hold feature Marcus came up with  is very cool, too. The sound clips he posted seems to prove the circuit works well. This, at least in my opinion, is a great start for building a monophonic guitar synthesizer. Oh, by the way, what do you think of that organ voice schematic?