I made a layout for the Low-Fidelity / Telephone / Noise Pedal from R.G.'s site and for the most part it works fine. The filter section work perfectly per R.G. schematic, but I am having a problem with the noise source side of the circuit.
This is my first attempt at a layout from schematic, so I suspect it is something I did, but I've been looking at this for 2 nights and I'm stumped. It's only six parts, and not complex.
Would anyone be willing to look at the noise portion just to make sure I didn't miss something silly in the layout? That portion of the circuit is circled in the image. I used 2n5088's for Q1 and Q2 and a .1uF for the unmarked cap per R.G.'s comments on the forum.
When I swing the panner to the "noise" side I hear a faint hiss that is relatively quiet, almost silent. I was expecting to hear a little more racket with more volume, but maybe my expectations are the problem. I will likely experiment with different transistors, but I would like to know that the layout is right and that my expectations are reasonable before doing that.
Thanks for any help.
George
R.G.'s Schematic
(http://www.geofex.com/FX_images/lofi.gif)
My version:
(http://home.comcast.net/~gprause/telephone_sc.gif)
My layout:
(http://home.comcast.net/~gprause/telephone_lo3.gif)
Quote from: chi_boy on December 29, 2009, 11:44:50 PM
I made a layout for the Low-Fidelity / Telephone / Noise Pedal from R.G.'s site and for the most part it works fine. The filter section work perfectly per R.G. schematic, but I am having a problem with the noise source side of the circuit.
...
When I swing the panner to the "noise" side I hear a faint hiss that is relatively quiet, almost silent. I was expecting to hear a little more racket with more volume, but maybe my expectations are the problem. I will likely experiment with different transistors, but I would like to know that the layout is right and that my expectations are reasonable before doing that.
I don't see anything wrong at first blush, but I wonder if I messed up the resistor values on the second transistor, or if the Q1 you have is breaking over at too high a voltage. It's also possible that the 2N5088 you are using for the noise transistor is just too quiet. Modern semiconductor processing has gotten much *too* good in many ways.
Can you test the pin voltages on the noise transistor and the noise amplifier transistor and post back?
What does this pedal do?
R.G. I'll check those voltages tonight and post. The 2N5088's are new Cetral Semiconductors. I verified pins against the datasheet and the part has the pins printed on the face. If the resistors look good, I also have some 2N2222's I could try.
Quote from: caspercody on December 30, 2009, 09:54:46 AM
What does this pedal do?
It creates a low-bandwidth, noisy audio output from a high bandwidth, quiet one. The idea is to make the output sound as though it went through a bad-connection telephone line.
There are two parts: one is a bandwidth limiting filter, the other is a noise source. Well, OK, three parts - there is a pan-pot to let you blend smoothly from pure low-bandwidth audio, no noise, through partial mixtures of the two, and all the way to pure hissy noise.
Quote from: chi_boy on December 30, 2009, 11:24:40 AM
R.G. I'll check those voltages tonight and post. The 2N5088's are new Cetral Semiconductors. I verified pins against the datasheet and the part has the pins printed on the face. If the resistors look good, I also have some 2N2222's I could try.
What I think may be going on is that the amplifier transistor may be running out of amplifying room and not getting enough voltage output. I'm right now going through some sims to figure out why I picked those resistors in the first place. It's been a while since I did that design. :icon_biggrin:
If the voltage at which the noise transistor's base-emitter breaks over is too big, it will saturate the gain transistor and not amplify the noise much. I'm trying to find the range of voltages that this works with. I can't imagine not having done this when I first did the design, but hey, sometimes I just do a forehead slapper. Getting the pin voltages on the transistors will tell me directly if this is the issue with your circuit and transistors, too.
R.G.,
The voltages are as follows:
Battery: 9.38
Q1
E: 6.41
B: 6.98
C: 6.49
Q2
E: 6.98
B: 0.00
C: N/C
Thanks again for revisiting this.
George
Quote from: chi_boy on December 30, 2009, 09:41:17 PM
Battery: 9.38
Q1
E: 6.41
B: 6.98
C: 6.49
Q2
E: 6.98
B: 0.00
C: N/C
The simple way to fix it is to change the 22K to a 68K or 75K. Your circuit's probably fine. The voltage from Q2 is high enough to saturate Q1 so it can't put much of anything out. My bad! Try upping to 68K to 75K - shoot, you could use 82K, 91K, maybe 100K - instead of 22K and see if you don't get more noise.
The first resistor I touched was a 100k, so it was the lucky one.
The voltages changed to this:
Battery: 9.38
Q1
E: 8.42
B: 8.38
C: 8.53
Q2
E: 8.38
B: 0.00
C: N/C
Oddly, the "noise" wasn't much different. Still remains pretty quite when panning.
Hmmm. There's more happening there.
Do two things.
One, try a 220K instead of a 100K.
Two: let me do some simulation and figure out what's going on.
Obviously , the first one is faster. The second one is for me to figure out why the base-emitter of the noise transistor appears not to be breaking over like it should. No way it should be going to over 8V without breaking. Which means that Mother Nature is trying to beat me on the head with something I've forgotten. :icon_biggrin:
R.G.
The 220k made a huge difference. Plenty of noise with lots of volume. Sounds just like the white noise on a "snow" screen on T.V.
I'm embarrased to say I may have made a connection error when testing the 100k. I'm going to put it back in to see if it was me or not. :icon_redface:
The voltages for the 220k are:
Battery: 9.37
Q1
E: 8.61
B: 8.45
C: 8.97
Q2
E: 8.45
B: 0.00
C: N/C
Is there any chance you have the 2N5088's in there backwards?
The reason I ask is that the breakover voltage of the 2N5088 base-emitter seems to be about 4.5-5V from the specs I found. The voltages you're reporting show it going to over 8V, which should not happen. I'm just guessing that with the transistor reversed, the collector-base junction would not be breaking over at all, and that would account for what we're seeing.
Otherwise it's back to the simulator for me.
===================================
Just as I hit send, your reply came up.
I'm glad it's working, but the comments above still apply - boy is it weird that a 2N5088 would have an 8.45V base-emitter breakover. "White noise on a TV screen" is what it's supposed to be, all right.
And no need to apologize for any errors. I'm still hunting down why it didn't work with the first set of resistors. :icon_biggrin:
Quote from: chi_boy on December 30, 2009, 11:33:54 PM
I'm embarrased to say I may have made a connection error when testing the 100k. I'm going to put it back in to see if it was me or not. :icon_redface:
OK, I feel better. I didn't miss it after all. I put the 100k back in and it is quiet again.
The "noise" that is generated is a nice smooth white noise type sound and is pretty consistant. Do you think there would be any benefit to changing the transistors to something like a 2N2222 or 2N3904 to get a different character to the noise? Maybe more snap crackle and pop?
Also, I used MC1458 opamps for the filter section. They are a dual 741. I'm not sure I like them yet, but they do add just a touch of distortion to the filtered signal.
Also regarding the pins, anything is possible, but I checked those several times. The transistors are printed with EBC right under the part number. I also included the orientation in the picture. I may be reading the schematic incorrectly too. EE gave me fits in school. I can't imagine why I would be messing with this stuff now. I must be drinking too much. ;)
Different transistors will give different noises, but what everyone was trying to get was a smooth hiss... :icon_lol:
There are different noise mechanisms. The predominant one you're getting is avalanche noise, which is the smooth hiss. Noise that snaps and pops is shot noise - novel name, eh? :icon_biggrin: And there is another noise mechanism that generates noise which gets bigger as frequency lowers, called burst or 1/F noise.
My proto on this thing ( I found some of my notes) worked OK as reported in the schemo. But it may be that transistors have gotten better again. I'll have to do some testing and perhaps update that circuit.
I'm glad that I could easter-egg it in for you. If you filter the noise before panning it in, it will change the effect too. I was trying to get the smallest, simplest circuit I could.
R.G.
Thanks so much for your efforts tonight. This really is a fun little pedal and I am tickled that it is working. I will play a little on my own now and tweak a little now that it works. As far as the noise goes, the smooth white noise with a little op-amp distortion may be the perfect combination. Time to let it ferment and see how it sounds in a day or two.
Thanks again,
George
Glad you got it working
I am very interested in this.
Would this be something you could do the "wish you were here" intro with ?
Quote from: Brymus on December 31, 2009, 01:20:24 AM
Would this be something you could do the "wish you were here" intro with ?
I think it would sound good for "wish you were here." That is actually closer to the sound I was going for myself. That intro has a little more static and whine and almost has a popcorn popping quality. This noise generator is more of a white noise, so it woulnd't be exact, but definatly close enough for rock-n-roll. Now that it's working, I am planning to try it with more bass cut. The filter is set at 300hz, but I want to play with it and see how it sounds at 600hz, 800hz, and maybe 1khz.
if you happen to have a metal can 2N2222 for Q1. solder a long wire to the rim of the can and connect that to a switch. switched to ground it's stock, switched to the enclosure (NOT grounded) it's an antenna that will pick up more noise and random radio.
> breakover voltage of the 2N5088 base-emitter seems to be about 4.5-5V from the specs I found
That may be a minimum?
It has been a looong time since I worked with these things. IIRC, in the 1970s, you could bet a beer the E-B breakover would be 6.3V-7.5V and never go thirsty. That's some kind of natural for the processes they used then. Then the "5V" number on the sheet is just a safety-margin down from 7V.
And again IIRC, it was risky to try this with a 9V battery, because the noise-power faded quickly as the battery drained. (Ah, but who uses battery today?) Perhaps more risky to also cleverly use the Vz as the bias for an amplifier? When done with 9V there was often a DC-block cap to the amplifier, which was biased conventionally (often just 1Meg C-E, grounded emitter).
Still a very clever low-parts design.
> Sounds just like the white noise on a "snow" screen on T.V.
That's just what it is, nearly. FM (TV) is de-emphasized (treble cut), this should be brighter. (And FM hiss is raw hiss through an FM demodulator, but I think the result is just random.) This plan lacks full bass response, a small difference (Q1 at 0.1mA and C9 at 1uFd gives 500Hz bass-cut). But over most of the "hiss zone" they are nearly pure random sources.
One thing to try, cost you a dime: raise C9 from 1uF to 10u and 100u. Bass-cut hiss is not natural, letting some rumble through may be more "realistic". Also there is 1/f noise, which gets greater at lower frequency. The audible effect is that the hiss is not constant from millisecond to millisecond.
And if you get deep (sub-Hz) 1/F noise boosted far enough to clip the amplifier path (which needs more than just Q1), you will get some "snap crackle and pop".
But the real problem with trying to raise non-Zener hiss up to "annoying" level is that you are likely to pick up all the buzz and even signal in the area. To a point, that may be good. But I think it will require obsessive shielding to be workable.
Change C3 0.1uFd to 1000pFd-500pFd. This shaves a trace more bass from the gitar, but also brings up the generous 1/f current-noise of your antique 1458. I have seen a phono preamp with a similar chip and too-small input blocking cap put out so much subsonic noise it tripped the "DC protect" relays in the speaker amp. This will also work with lusty 5532, but won't work with TL072 (no gate current, thus no current noise).
> The "noise" that is generated is a nice smooth white noise type sound and is pretty consistent. Do you think there would be any benefit to changing the transistors to something like a 2N2222 or 2N3904 to get a different character to the noise?
No. This is raw semiconductor physics. As RG says, avalanche noise. '5088, '2222, '3904 are all essentially the same thing, sold in different sizes and proportions ('5088 may have a thinner base, real '2222 has a bigger die). Back in the late 1960s there were audible differences between -foundries- (some were cleaner than others), but not across devices from the same fab. Since the 1970s all fabs have got very-clean, and I doubt there is any audible difference.
Which does suggest one line of extended research. Get old crappy Germanium devices. Wire for gain and follow with lots more gain. Their dirty surfaces give lots of excess and 1/f noise. However we know from popular Ge FX pedals that even odd-lot Ge devices do not hiss excessively at guitar level. So you still need considerable gain.
Try the digital pseudo-random noise generators. Short registers produce not-very-random hiss. However they are repetitive: mine made a distinct thump every 2 seconds. On long room-tuning sessions, this was annoying. You may try 2 or 3 such hissers running on different clocks to try to "randomize" the loop artifacts. But this is getting complicated.
Look, this is the 21st century, and 2010 already. You can buy "message recorder" chips/modules for about what a handful of CMOS registers cost. They sell stuffed bears with these modules so grandkid can send a personal message to grandma. And they may turn up in post-holiday sales. Anyway, find a hiss you like, record it, loop playback. 30 seconds of time is probably enough to mask the repeat.
Quote from: PRR on January 01, 2010, 05:07:49 PM
> breakover voltage of the 2N5088 base-emitter seems to be about 4.5-5V from the specs I found
That may be a minimum?
It is, assuredly. The old standard was that base-emitters break at 6V, which is the reverse-BE spec on a 2N3904. I took that maximum as being a telegraph for saying "we'll ship anything that meets gain spec, even if the B-E is a little thin."
QuoteAnd again IIRC, it was risky to try this with a 9V battery, because the noise-power faded quickly as the battery drained. (Ah, but who uses battery today?)
It was - and it does. But who does? :icon_biggrin:
QuotePerhaps more risky to also cleverly use the Vz as the bias for an amplifier? When done with 9V there was often a DC-block cap to the amplifier, which was biased conventionally (often just 1Meg C-E, grounded emitter).
Still a very clever low-parts design.
That's what I was after going voltage-mode instead of the more-common current mode circuit.
Quote
Try the digital pseudo-random noise generators. Short registers produce not-very-random hiss. However they are repetitive: mine made a distinct thump every 2 seconds. On long room-tuning sessions, this was annoying. You may try 2 or 3 such hissers running on different clocks to try to "randomize" the loop artifacts. But this is getting complicated.
Even simpler, get the PIC 12F509 or one of the PIC 10Fxxx chips. You can get these in 8-pin dip packages and program them for something in the 64-bit class of feedback shift register noise. A 31-bit feedback shift register repeats in 2.147 billion steps; if you set the step frequency to something out of the audio band for good verismillitude on wideband noise, say maybe 44kHz, the repeat would be something like 13.5 hours for a repeat. A 63 bit register (which the Math Devil made me calc out) would repeat once every 6.6 million years if your battery lasts that long. :icon_lol: Maybe we could use the smaller register length or higher rep rate.
These PICs are about $1.00. I would have done that, but then *-no one-* would ever have built one. :icon_biggrin: For some reason, no one here has tumbled to using PICs for logic or digital functions. I tried to push that for a while, but gave up when it was met with a deafening silence. The digital forum seems to have dropped into the DSP-only rut.
But yes, one eight pin dip and maybe a couple of resistors and caps could do a bang-up noise generator for cheap - and good.
Quote from: R.G. on January 01, 2010, 06:04:28 PM
Even simpler, get the PIC 12F509 or one of the PIC 10Fxxx chips. You can get these in 8-pin dip packages and program them for something in the 64-bit class of feedback shift register noise. A 31-bit feedback shift register repeats in 2.147 billion steps; if you set the step frequency to something out of the audio band for good verismillitude on wideband noise, say maybe 44kHz, the repeat would be something like 13.5 hours for a repeat. A 63 bit register (which the Math Devil made me calc out) would repeat once every 6.6 million years if your battery lasts that long. :icon_lol: Maybe we could use the smaller register length or higher rep rate.
These PICs are about $1.00. I would have done that, but then *-no one-* would ever have built one. :icon_biggrin: For some reason, no one here has tumbled to using PICs for logic or digital functions. I tried to push that for a while, but gave up when it was met with a deafening silence. The digital forum seems to have dropped into the DSP-only rut.
But yes, one eight pin dip and maybe a couple of resistors and caps could do a bang-up noise generator for cheap - and good.
I think many folks on here are starting to pick up on PIC stuff now. I think the draw back is the learning curve plus the cost of programming tools. If you think about all of the resources available purely for guitar pedals, it seems odd that no one has offered the paint by numbers route for PIC programming yet.
Quote from: tiges_ tendres on January 02, 2010, 01:58:49 PM
I think many folks on here are starting to pick up on PIC stuff now. I think the draw back is the learning curve plus the cost of programming tools. If you think about all of the resources available purely for guitar pedals, it seems odd that no one has offered the paint by numbers route for PIC programming yet.
It does, doesn't it?
> PIC 10Fxxx .... A 31-bit feedback shift register repeats in 2.147 billion steps
Cool! Wudda liked that back in the day. And you can't beat the parts-count/cost.
But George said "nice smooth white noise ... Maybe more snap crackle and pop?" Which opens a big can of worms about psycho-acoustics and un-randomness. But we know what he means. Most of the interesting "hiss" is not pure random.
Mathematicians have labored to reach maximal randomness in pseudo-random machines. All possible combinations equally. What George's ear seems to want is less uniform randomness. Big chunks of curd. Grit in the groove.
Obviously we can mis-wire the shift register. Get hundreds of 1s in a row more often than pure-random. But how to be sure you don't get thousands of the same bit in a row (which would be silence)? It's a puzzle my uncle might love. He'd point out that his brain-time is worth more than many alternate hiss sources.
Trying to specify "good snap crackle and pop" is hard. But I know good hiss when I hear it. If I can hear it, I can record it. And if I don't have the exact-right hiss, a digital audio editor can paste and mix and mangle to taste. A layer of plain hiss, a dollop of off-station AM radio, sprinkled with the lead-in groove from the copy of Live Dead which survived The Party Of 1975.
Which would be absurd in days of tape and razors, but is now just a bit more expensive than a PIC. (And can be loaded with stone-age minds.) Here's a fancy kit (http://www.canakit.com/2-minute-digital-voice-recorder-player-with-repeat-function-kit-ck330m2-uk330m2.html) to stash 2 minutes of audio and repeat for 100 years. Here's another with 6 tracks. (http://store.qkits.com/moreinfo.cfm/MXA023) I know they come VERY much smaller and cheaper, toy-level.
Futurlec has a list of recorder chips:
http://www.futurlec.com/ICSFOthers.shtml
"Special Function - Voice Record/Playback"
$6-$12 for the chip. $6 includes a Meg of RAM. High-cut at 3.4KHz to 1.7KHz, trade-off with time. A full-range hissbox would need more. A telco FX box would be fine at 3KHz or probably less.
However the in-stock chips seem to be awful fancy. Some need a CPU to get going at all. We just want a RECord button, and auto-play otherwise. So it may come down to dissecting stuffed bears.
Photo-frames with recordable audio:
Circle of Friends ... space for 8 photos and 8 separate voice messages! ...each 7-8 seconds long (http://www.christianbook.com/Christian/Books/product?item_no=17360X&item_code=WW&netp_id=469157&event=EBRN&view=details) $30
Dad Greeting Card Voice Frame, 10-second message (http://www.christianbook.com/dad-greeting-card-voice-frame/pd/173560?item_code=WW&netp_id=469154&event=EBRN&view=details) $25
Recordable Postcard (http://www.discountschoolsupply.com/Product/ProductDetail.aspx?product=25142&es=18734220000W&utm_source=CSE&utm_medium=weblink&utm_campaign=froogle&cvsfa=408&cvsfe=2&cvsfhu=3235313432) - Clearance Price: $3.97:
...high quality, 10-second recordable voice chip
To record a message, click switch to 'ON'
Hold down the 'REC' button while recording
When finished, click switch to 'OFF' to keep your message saved
Push 'PLAY' to play it back
Well, you guys have blasted way past my abilities. There are some very nice ideas here, but for me at least, they are for the most part impossible to pursue. On the analog side though, I did make some personal progress.
I played a bit with the transistors and did find a difference in the 2N5088's I had on hand. The Central Semi's required an R21(22k) of 220k to work and didn't work with a 100k. I really should have tried some between values, but did not. I switched in some Fairchild 2N5088's and R21 was functional at 68k.
I did play around with swapping in a couple of different transistors and I did hear at least a minor difference for one of them. The others were all the same. The only one that was a little different was the 2N3904 (R21= 68k). It seemed to have a low rumble that the others lacked. It sounded almost like two different tracks on top of each other. The white noise track (hiss) was the same as the others, but the additional track was low and rumbly, (1/F noise?). Pretty much like this:
http://www.ciphersbyritter.com/NOISE/ZENER1.WAV (http://www.ciphersbyritter.com/NOISE/ZENER1.WAV)
Note: This is NOT my recording.
The final noise section I am settling in on is the 2N3904 transistors with R21 at 68k. I also changed C9 to 100uF as suggested. I think this may have allowed some more rumble, but it is a little subjective.
On the filter side I swapped out R10 and R11 from 56k to 15k. From what I calculated this raised the lower frequency 300Hz to 1.1kHz. The result is a great LoFi A.M. radio sound, complete with static. I fully plan to box this one up.
More "character" in the noise section would be fun, but I don't really think it's a necessity. Although I still find myself obsessing over it. I can't explain why.
If it was within my capability I might change a thing or two about the circuit now that I have played with it a bit.
1) I really can't see an application for the noise only option in the panner. When fully in that mode, no guitar signal passes though. Personally I would have the "noise" as an adjustable addition to the constant guitar volume and eliminate the panning all together.
2) Since I am still obsessing over noise, the ability to add in a second, different, noise source would be interesting. The user would then be blending 3 sources for the final product. Of course I haven't found that noise source yet, so this may be moot.
3) Someone suggested adding the noise before the filter, but I can't find the post to give credit. In listening to this circuit, I think that would be an enhancement, but would need to hear it first. A switchable injection point would be the ultimate tweak.
4) Adjustable filter settings would be interesting. I did try a layout to use rotary switches to change the filter resistors. When I breadboarded it, it worked fine, and I don't doubt it would work in reality. I just ran out of talent when trying to do the layout so gave up on it.
Of course this all adds complexity that wasn't part of the original design criteria, and is in no way intended as criticism. It's more like [my] talentless enthusiasm for the project.
Overall I am surprised this schematic has been around for so long and has not been picked up. There are no layouts to be found anywhere. It is significantly more complicated than a LoFoMoFo, but for those that don't care for that design, this one may be a good solution.
R.G. and all, thanks for the help and suggestions. And thanks for a fun little circuit!
Cheers,
George
Quote from: PRR on January 02, 2010, 04:57:56 PM
> PIC 10Fxxx .... A 31-bit feedback shift register repeats in 2.147 billion steps
Cool! Wudda liked that back in the day. And you can't beat the parts-count/cost.
I was pretty sure I wasn't the first to think of this. Check this link from EDN, 2003:
http://www.edn.com/article/CA313057.html (http://www.edn.com/article/CA313057.html)
Note that this is an attempt at a purist's noise generator. Any one of the 12C508s will do noise suitable for audio all by itself, and drive a pinking filter directly as well. The parallel adding ensures better frequency distribution to get a true-Gaussian signal. I doubt I can hear that well, nor can most others. And he got the same number of states for 31 bits I did! :icon_biggrin:
QuoteBut George said "nice smooth white noise ... Maybe more snap crackle and pop?"
Yeah, that takes finding a device that has snap/crackle/pop breakdown. It's much simpler to generate randomly distributed crackle noise.
To do this, one takes a white noise signal, low pass filters it to get the degree of density one likes, then uses the noise as an input to a comparator, the other input being a variable reference level. The output of the comparator can be capacitor coupled to make impulses, or fed into the trigger of a one-shot, and the level of the impulses out used as the snap/crackle/pop signal. It can be added back to the white noise, or even gate the white noise. But all this gets outside the simple circuit realm.
Finally finished building this circuit.
I used chi_boy's first layout (I had a PCB made before he updated it):
http://www.diystompboxes.com/smfforum/index.php?topic=73881.0
Long story short: Q2 needs to be flipped. I should have realized this if I carefully read the schematic and looked at the transistor's data sheet.
I wound up settling on a 100k resistor to get the noise section going.
I did these mods:
http://www.diystompboxes.com/smfforum/index.php?topic=25185.msg164559#msg164559
http://www.diystompboxes.com/smfforum/index.php?topic=26214.0
Impressions:
Cool circuit, though the white noise can get grating after a while.
I have to agree with chi_boy, some "character" to the noise would be beneficial, as would a filter for the noise.
The adjustable filter for the guitar signal is excellent though. Thanks to Mark for the suggestion. There is some distortion depending on your settings and attack. It sounds good though.
I tried some other things through this circuit and realized this is a good candidate for "dirtying" up your sound. Not as obvious as distortion for example, but noticeable.
The other fun/useful thing to use this for is contrast. Play a lick/riff/arpeggio with the effect off, switch it on and play it again, repeat. Interesting for a quick "color" change.
Thanks again to all involved!
That's kinda funny. I've been working on the same project. I did Marks mods too and also changed the panner to a mixer.
For the noise section I made a white noise generator based on this: http://www.musicfromouterspace.com/analogsynth_new/NOISECORNREV01/schematic_pg1.pdf (http://www.musicfromouterspace.com/analogsynth_new/NOISECORNREV01/schematic_pg1.pdf), but converted to 9v. It has smooth white to frying eggs. I like it. I also added whine based on the synth stick, but with 3 oscillators. I also have it set to be able to switch the noise from before or after the filter of the main board.
Needless to say, the scope has crept just a little beyond R.G.'s original vision. But it is a hobby, not a business, so what the heck.
Mine is in the process of being etched and drilled. This part is new for me so I'm climbing up that learning curve, along with learning Eagle.
I'll post my layouts once I verify it all works. For now it's all spread out on 3 breadboards.
Cheers,
George