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DIY Stompboxes => Building your own stompbox => Topic started by: digi2t on June 22, 2017, 12:12:05 AM

Title: Spaceman Sputnik II
Post by: digi2t on June 22, 2017, 12:12:05 AM
Managed to get my hands on this piece of vaporware. Ironically, after failing miserably to buy one when they would become available, I find one for sale about 30 minutes from my house. Go figure...

Anyway, let's get on with it. Gutshots;

(http://i214.photobucket.com/albums/cc196/digi2t/Sputnik%20II/DSCF5316_zpsoegjvcqs.jpg) (http://s214.photobucket.com/user/digi2t/media/Sputnik%20II/DSCF5316_zpsoegjvcqs.jpg.html)

(http://i214.photobucket.com/albums/cc196/digi2t/Sputnik%20II/DSCF5317_zpsxy3bqutj.jpg) (http://s214.photobucket.com/user/digi2t/media/Sputnik%20II/DSCF5317_zpsxy3bqutj.jpg.html)

As always, they're up to their usual shinanigans, like defacing components, weird a$$ values, and whatnot, but this time, they went as far as embedding the traces between the ground planes. Needless to say, lots of time poking and prodding with the multi-meter was spent, trying to follow where everything was going. This is my preliminary schematic;

(http://i214.photobucket.com/albums/cc196/digi2t/Sputnik%20II/Schematic_zpsoelvpwcz.jpg) (http://s214.photobucket.com/user/digi2t/media/Sputnik%20II/Schematic_zpsoelvpwcz.jpg.html)

I've got some unknowns here, specifically one component that reads as "N-Channel FET" on the Peak meter, but it only identifies the gate, so I'm unsure of with is the source and the drain. It might be an MPF102... maybe.

It's an interesting circuit. Really nice fuzz, with a "Drift" mode which basically send the unit into oscillation. The oscillation is adjustable, you can have it on full time, or set it to be attack sensitive. Very reminiscent of the Skyripper in a way. The filtering is lovely, really lots of usable tones in this thing. It's as if they took the Gemini III, and went a totally different direction with it.

Anyway, what do your eagle eyes see? Does this schematic make sense? Wouldn't surprise me if trace(s) are still hiding. :icon_lol: 

Title: Re: Spaceman Sputnik II
Post by: diy-tubes on June 22, 2017, 04:58:03 AM
2 ge transistors are russians, no marking?
Title: Re: Spaceman Sputnik II
Post by: digi2t on June 22, 2017, 06:36:11 AM
3 Russian transistors. The only transistor looking part that I could lift a marking off was the VP3203, the rest were all sanded and painted over. The Peak meter gives me a reading on the first two, and diode testing the third one gives me the same pinout as the two others. I would hazard to say that they may all be the same model. The Peak gave me a gain of mid 60's for Q1, low 80's for Q2, and Q3 is unknown, but breadboarding will be the ultimate fact finder. Where the gains are concerned, and the shape of the transistors, maybe something out of the MP 15/20/etc. series. Probably in the "B" gain bracket.

EDIT:

Just noticed a problem. Low filter, in the middle position won't work, nothing going to the base of the second Ge transistor. Must be a trace going somewhere from here. I'll check it tonight.
Title: Re: Spaceman Sputnik II
Post by: diy-tubes on June 22, 2017, 12:42:58 PM
Do you use DCA55 or DCA75? DCA75 gives a bit higher measurements.
What about transistors housing, it can be many types: similar hFE (80) gives GT308/1T308, MP series will give a bit lower hFE (only Q1 can be used here, traditional choice of low noise MP39B, P28 and others, or something simple like MP42) Higer hFE gives P416 in the same housing. But I think any with the same pinout and hFE must do the job.
Title: Re: Spaceman Sputnik II
Post by: digi2t on June 22, 2017, 12:50:13 PM
DCA55. To date, I haven't really been able to justify moving up to the 75. Overkill for what I need.

Your call on the transistors is probably spot on.

That missing link between Q1 and Q2 with the switch in the middle is really bugging me. Can't wait to poke at it some more tonight.
Title: Re: Spaceman Sputnik II
Post by: thermionix on June 22, 2017, 01:17:05 PM
Can't wait to poke at it some more tonight.

Sig-line material right there.

(I'll delete it if you want me to.  Will anyway after a while when I get bored of it.)
Title: Re: Spaceman Sputnik II
Post by: digi2t on June 22, 2017, 02:20:29 PM
Can't wait to poke at it some more tonight.

Sig-line material right there.

(I'll delete it if you want me to.  Will anyway after a while when I get bored of it.)

It's all good brother. It's like a Trump tweet, once it's out there... :icon_mrgreen:
Title: Re: Spaceman Sputnik II
Post by: pinkjimiphoton on June 22, 2017, 03:36:56 PM
dino, i've found that reversed beta'd ge transistors will often read as an n channel fet.

i think at a certain point of leakage, the gain evens out either way its oriented, but it appears to the tester as a fet
and will often work as one.

if this has russkie q's in it already, i'd wonder about that. probably wrong, but i've seen some weird shit too!
Title: Re: Spaceman Sputnik II
Post by: pinkjimiphoton on June 22, 2017, 03:37:54 PM
Can't wait to poke at it some more tonight.

Sig-line material right there.

(I'll delete it if you want me to.  Will anyway after a while when I get bored of it.)

It's all good brother. It's like a Trump tweet, once it's out there... :icon_mrgreen:

its gonna be 'UGE.....
Title: Re: Spaceman Sputnik II
Post by: digi2t on June 22, 2017, 04:37:24 PM
dino, i've found that reversed beta'd ge transistors will often read as an n channel fet.

i think at a certain point of leakage, the gain evens out either way its oriented, but it appears to the tester as a fet
and will often work as one.

if this has russkie q's in it already, i'd wonder about that. probably wrong, but i've seen some weird shit too!

Naw, Ge is out of the question for the one with the "?????". It's a plastic package, which they painted silver. If you look at the pic I posted, there are four in a row, with a fifth one further down, on the left side. The first and second from the top are for the Mill bypass. The third one is painted the exact same color as the second, which would lead me to believe that it's another BS170/2N7000 MOSFET. The fourth they painted silver, and the the Peak tells me that it's an N-Channel FET, and the gate is not the same pin position as the others. N-Channel FET with a gate on the end, that makes me think J201 or similar. The fifth one, the space boys got careless. They painted it with a darker green paint, but didn't grind it, so the writing was visible through the paint. Other than the Mill bypass, I'm not quite sure what the MOSFET/FET combo is doing here, especially when the drain of the Mill bypass MOSFET is also feeding the gate of the next MOSFET. Mill bypass of the DRIFT circuit? Acting as a cut out for the Q1 signal from hitting Q3 maybe? I'm not familiar with this arrangement at all.

Well, more "poking" revealed a missing trace. Also corrected a resistor value. Those 1/8w resistors are so tiny, the red looks like brown and vise versa.  :icon_evil: Here's the update;

(http://i214.photobucket.com/albums/cc196/digi2t/Sputnik%20II/Schematic_zpscdgugmph.jpg) (http://s214.photobucket.com/user/digi2t/media/Sputnik%20II/Schematic_zpscdgugmph.jpg.html)

I missed a connection between the 100K/123 junction, and the Q2 base. Audio now floweth.
Title: Re: Spaceman Sputnik II
Post by: pinkjimiphoton on June 22, 2017, 05:59:35 PM
you are a very sick young man. i respect that and salute thee!!  :icon_mrgreen:
Title: Re: Spaceman Sputnik II
Post by: digi2t on June 22, 2017, 09:25:45 PM
More corrections. Unfortunately, the new glasses haven't helped.  :icon_sad: The trimmers make more sense now.

(http://i214.photobucket.com/albums/cc196/digi2t/Sputnik%20II/Schematic_zpszjpgg4lv.jpg) (http://s214.photobucket.com/user/digi2t/media/Sputnik%20II/Schematic_zpszjpgg4lv.jpg.html)

The unknown FET (?) is still, well... unknown, but I'm thinking that maybe it's being used as a sort of threshold gate for the oscillation. By adjusting the SCAN voltage, you can adjust where the oscillation will kick in, according to the signal strength coming from Q3 collector. You crank up the SCAN, and the oscillation is on full time, turn it down and you can have it come on at a desired signal output level.

As for the BS170 below it, I'm guessing it's switching off the unknown FET when in bypass, maybe to prevent any oscillation audio from bleeding into the clean signal?

Does that make sense, or am I whistling Dixie here?
Title: Re: Spaceman Sputnik II
Post by: bluebunny on June 23, 2017, 02:47:30 AM
DCA55.

As I understand, the 55 doesn't have the chops to differentiate between D and S, so all it does is identify the gate on a JFET.
Title: Re: Spaceman Sputnik II
Post by: digi2t on June 23, 2017, 07:46:14 AM
DCA55.

As I understand, the 55 doesn't have the chops to differentiate between D and S, so all it does is identify the gate on a JFET.

Not my experience. I think the problem stems from the fact that I'm testing the components in situ, so the surrounding components are messing with the readings. If I take a FET or MOSFET and test it directly, the 55 has always been able to tell me what's what. The same applies to testing transistors. In some cases, depending on the surrounding cast of characters, the 55 might give you a proper declaration, other times, it comes back with "Common diode network", which is understandable considering that other components in the circuit are influencing the reading. Another thing when test transistors while they're in the circuit, the gain/leakage readings  may or not be accurate. I would tend to take them with a larger margin of error in this case.

All in all though, it's a pretty fine tool.
Title: Re: Spaceman Sputnik II
Post by: bluebunny on June 23, 2017, 07:51:58 AM
Ah, OK. I was misinformed. Thanks Dino. (I should really have tried it myself!)

Title: Re: Spaceman Sputnik II
Post by: digi2t on June 23, 2017, 08:45:51 AM
Ah, OK. I was misinformed. Thanks Dino. (I should really have tried it myself!)

Marc, my sincerest apologies, you are correct where JFET's are concerned. Only the gate is identified. It will however identify all the pins on MOSFET's.

I spoke too soon. Sorry.

On the other hand, your astute observation on the 55 helps reinforce that the unknown component is indeed a JFET. Thanks!!

I think I have enough info now to start breadboarding this sucker.
Title: Re: Spaceman Sputnik II
Post by: diy-tubes on June 23, 2017, 09:45:30 AM
Measuring JFET with DCA75 or chinese transistor testers like gm328 can measure Vgs(off), so we can suppose the type. Even fake ones like modern J201 with Vgs(off) about 1.2-1.5.
Common diode network DCA will show if hFE is too low, or if it fail to determine the type.
BTW do you measure in curcuit? DCA manual warn from it.
Waiting for breadboarding results! At least I will try to offer russian ge transistors types with proper hFE. :)
Title: Re: Spaceman Sputnik II
Post by: bluebunny on June 23, 2017, 09:53:28 AM
No problem, Dino!  Sometimes I just regurgitate stuff that other far cleverer folks say in the hope that I appear intelligent.  Doesn't always work!   :icon_rolleyes:   Either way (and in the best scientific tradition), we end up learning something.  And either way, I'm intrigued by what happens next.  Over to you.  :D  <reaches for popcorn>
Title: Re: Spaceman Sputnik II
Post by: digi2t on June 23, 2017, 10:43:45 AM

Common diode network DCA will show if hFE is too low, or if it fail to determine the type.
BTW do you measure in curcuit? DCA manual warn from it.


In cases like this, where I'm really not interested in removing components, I'm not looking for accurate numbers. Just a simple pinout to point me in the right direction. I understand that the readings can/will be erroneous measuring in circuit, so I don't put that much faith in them. It gets me into the ballpark, and breadboarding gets me the more accurate numbers.

If the 55 does give me numbers in circuit for Ge transistors, I've noticed that the gains always tend to be lower, and the leakage higher, than what the transistor would actually measure if it was off the board. As such, I've developed a sort of "guesstimation" of what it is probably close to. For instance, if I see "hFe 62" and "leakage = 0.72mA", I find that choosing a transistor in the mid 70's, with a leakage around 0.20 or better, usually gets me pretty close to the voltages in the original circuit. Not an exact science by any stretch, but it helps noobs like me to keep plodding along. :icon_biggrin:

In the case where the 55 returns "Common diode network", I refer to the DMM diode test for pinouts. Breadboarding then becomes the process of elimination where gains and leakages are concerned.

Finally, where tone is concerned, well... everything goes out the window. You can plug in an AC128, and then an MP20, with exact same gain and leakage specs, and get two totally different feels from a circuit. Why, I don't know, and frankly, I could care less. It's that unknown that keeps me interested. A fool in blissful ignorance.  :icon_mrgreen:

No problem, Dino!  Sometimes I just regurgitate stuff that other far cleverer folks say in the hope that I appear intelligent.  Doesn't always work!   :icon_rolleyes:   Either way (and in the best scientific tradition), we end up learning something.  And either way, I'm intrigued by what happens next.  Over to you.  :D  <reaches for popcorn>

Thanks just the same Marc. You're absolutely correct, we always have more to learn.
Would that happen to be buttered popcorn by any chance? Yum! :icon_lol:
Title: Re: Spaceman Sputnik II
Post by: diy-tubes on June 24, 2017, 05:11:35 AM
Just remark for DCA55 users, that DCA55/75 not intended for testing in circuit. It can be damaged by DC stored in capacitors, or if AC/DC is connected.
digi2t, thank you for sharing you experience!
Title: Re: Spaceman Sputnik II
Post by: digi2t on June 24, 2017, 09:17:37 AM
Just remark for DCA55 users, that DCA55/75 not intended for testing in circuit. It can be damaged by DC stored in capacitors, or if AC/DC is connected.
digi2t, thank you for sharing you experience!

The AC/DC connected most certainly makes sense, and to date, I've never dreamed of testing with the power on. My brain sort of figured that doing that would result in "bad things" happening. Then again, it could give me an excuse to buy a 75... right? (Aw dang! It blew up... aww shucks.):icon_mrgreen:

As for the caps, I must admit, it never dawned on me, so I guess I've been lucky that nothing's happened to my 55 yet. I suppose I could always drain the caps to ground before testing directly. Like I said, in some cases, removing components for direct testing isn't an option, especially with something of limited availability, not to mention Ge transistors that can be easily damaged.

Gonna start breadboarding this weekend. There's some component values that I don't have, so I'll fake them by chaining other values together while I'm waiting for my order to come in. I'll at least be able to see if I'm in the ball park. Stay tuned folks....
Title: Re: Spaceman Sputnik II
Post by: digi2t on June 25, 2017, 11:34:47 AM
Another update. Noticed that I had the DRIFT footswitch in the wrong position on the schematic, and I retook the voltages. Also managed to get a reading for the third Ge transistor on the DCA55. They're not accurate mind you, just a starting point. The voltages will take you the rest of the way. I also added the resistances of the trimmers as they are set. This should help in narrowing down the correct transistors for the first and third spots.

(http://i214.photobucket.com/albums/cc196/digi2t/Sputnik%20II/Schematic_zpscdvthkl4.jpg) (http://s214.photobucket.com/user/digi2t/media/Sputnik%20II/Schematic_zpscdvthkl4.jpg.html)
Title: Re: Spaceman Sputnik II
Post by: digi2t on June 27, 2017, 10:55:24 PM
Well, good news folks!

I have it on the breadboard right now, and it pretty well emulates what the original does. Instead of Russian transistors, I pulled out some Japanese 2SB172's instead. Call it the "Nippon" instead of the "Sputnik". Anywho, they're all 0.03mA or better leakage-wise, 72 in Q1, 82 in Q2, and 80 in Q3 for gain. The voltages are more or less aligned with the original, +/- 0.1 of a volt here or there. I'm attributing the slight variance to the fact that I didn't have any 475K resistors, so I have 470K's in there right now. Instead of two 10K's below the CALIBRATE pot, I used a single 20K. Also, on the high filtering, a 472 cap is filling in for the 502 while I wait. The 243 CALIBRATE cap is being temp'ed by a 273.

As for the unknown JFET, I tried a 2N5457, 2SK30Y, and a 2SK30GR. As for the Ge diode, I tried a 1N60, 1N270, and a Russian D9E. The combo of the 2SK30Y and D9E gave the best performance when it came to setting the edge of oscillation, and the best decay as well. Funny, I was singing the praises of the D9E earlier today, and once again, it didn't disappoint. My source and drain voltages are a bit higher than the original when the gate is set at 6.26v, but again, I'm attributing this to the missing 5K at the B-C of Q1. Once my order comes in, I'll be able to tweak it some more, and retest the voltages.

I'm almost positive that the BS170 that's just below the unknown JFET is used in conjunction with the Mill bypass to switch the JFET off. Otherwise, I think the oscillation would bleed into the audio in bypass. This is my theory, but it would be cool if some one with more brains on this could confirm.

All in all, pretty fuzzy, and when you kick in the DRIFT (oscillation), you can get all sorts of textures. The filtering is pretty cool as well. With the DRIFT off, at lower settings, it can be discreet. At higher settings, more effective. With the DRIFT on, freakin' awesome. Tone-wise, it's similar to the original, but the stand-in values, as well as different transistors, give it a different flavor. Say... a bit crunchier.

I'll audition some Russian transistors as well. I've got lots of them. The 2SB172's do sound pretty rad though.

More to come....  :icon_biggrin:
Title: Re: Spaceman Sputnik II
Post by: stringsthings on June 28, 2017, 10:10:25 PM
Interesting!
Title: Re: Spaceman Sputnik II
Post by: digi2t on June 28, 2017, 10:40:24 PM
Well, this is pretty much it. I've played and I've tweaked, and I've tweaked and I've played with it. This is what I have;

(http://i214.photobucket.com/albums/cc196/digi2t/Sputnik%20II/Schematic_zpsdxtq4sfa.jpg) (http://s214.photobucket.com/user/digi2t/media/Sputnik%20II/Schematic_zpsdxtq4sfa.jpg.html)

An interesting mod would be a diode polarity reversing switch for the Ge drift diode. I tried a BAT48 in here as well, and it works pretty well. A reversing switch changes the character of the drift effect by raising the oscillation onset point on the SCAN pot. While the initial oscillation attack is a bit more subdued with the diode the other way around, the decay is much nastier. I'll be adding a toggle for this on my build.

As I expected, the second MOSFET gets it's cue from the Mill. bypass, and kills the oscillation by grounding the JFET when you switch to bypass. The drift LED will still stay on if the footswitch is engaged, but you won't get any screaming oscillation bleeding into the audio. Of all the JFET's I've tried; 2N5457, 2N5485, BF245A, 2N3819, 2SK30A-Y, 2SK30A-GR, and J201, the J201 and 2SK30A-Y seem to perform the best. The 2N5457 is my second choice.

Going to try to clear up the bench (somewhat), and try to shoot a video tomorrow.
Title: Re: Spaceman Sputnik II
Post by: stringsthings on June 29, 2017, 11:58:40 PM
Looking forward to the vid!  I always enjoy reading about your circuit pursuits.
I need to build me one of them.  Maybe the spaceman!
Title: Re: Spaceman Sputnik II
Post by: digi2t on June 30, 2017, 06:50:42 AM
Well, I've decided to kick the bucket where Photobucket is concerned  :icon_evil:. I've uploaded it to the Gallery now. Here's the schematic again;

(http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=53154&g2_serialNumber=1)

Here's the video. First half deals with the original, second half with the breadboarded version. It's long winded, I know, I suck at these things, so feel free to shuttle through it.



Like I mention in the video, the hi and lo filter switches are more discreet when just on fuzz mode. Of course, a crappy camera mic doesn't help their cause either!  :icon_lol: Anyway, what I have on the breadboard for the video, I combo'd some of the components to closer match some of the weird values of the original.
Title: Re: Spaceman Sputnik II
Post by: stringsthings on July 01, 2017, 08:03:33 AM
Very good video.  Lots of unusual sounds.
Title: Re: Spaceman Sputnik II
Post by: digi2t on July 01, 2017, 09:09:48 PM
Here ya go folks. Not build verified yet, but back trace to the schematic looks good. Let me know if you spot something that's out.

(https://s23.postimg.org/bb2agys7r/Sputnik_II_vero.jpg) (https://postimg.org/image/bb2agys7r/)

To help with the cuts, a reversed image;

(https://s15.postimg.org/72sxyzvd3/Vero_reverse_cuts.jpg) (https://postimg.org/image/72sxyzvd3/)

Use the schematic to get your voltages dialed in. The gains are merely guidelines, depending on the transistor used, you can tweak it to your liking. If you can get the voltages close, you won't be disappointed. As for the weird ass component values, you can try more conventional values, or if your anal, hunt down the original values. Your call.

EDIT:

Images are updated. Forgot the transformer number, and the number of jumpers was incorrect. The "Diode reversing" switch is my own addition, after my breadboard testing. If you don't want it, then just connect from the vero direct to the Drift 5 lug. Also moved a few items around.

Title: Re: Spaceman Sputnik II
Post by: PMowdes on July 03, 2017, 10:12:28 AM
Here ya go folks. Not build verified yet, but back trace to the schematic looks good. Let me know if you spot something that's out.

(https://s17.postimg.org/x4wpzgbzf/Sputnik_II_vero.jpg) (https://postimg.org/image/x4wpzgbzf/)

To help with the cuts, a reversed image;

(https://s15.postimg.org/72sxyzvd3/Vero_reverse_cuts.jpg) (https://postimg.org/image/72sxyzvd3/)

Use the schematic to get your voltages dialed in. The gains are merely guidelines, depending on the transistor used, you can tweak it to your liking. If you can get the voltages close, you won't be disappointed. As for the weird ass component values, you can try more conventional values, or if your anal, hunt down the original values. Your call.

EDIT:

Images are updated. Forgot the transformer number, and the number of jumpers was incorrect. The "Diode reversing" switch is my own addition, after my breadboard testing. If you don't want it, then just connect from the vero direct to the Drift 5 lug. Also moved a few items around.

Dino

A coupla things I've noticed.

You are missing D3 from the BOM, and I think that you may have D1 and D3 mixed up (unless they are the same)

You seem to have two 3.92K resistors but I can only find one on the schematic.  Is R20 the CLR for the stomp LED?  in which case does it need to be such an obscure value?

Can you update the Vero so that the transistor numbers are visible.  They are obscured by the pin orientation.

Thanks

Phil
Title: Re: Spaceman Sputnik II
Post by: digi2t on July 03, 2017, 12:12:41 PM
Gotcha Phil.

The CLR's are 3.6K, and there's only one 3.92K resistor.

There are two THREE diodes, and two LED's.

As for the obscure values, these are the original values. What's in there is what's represented. That said, there's no law that says that the builder cannot sub more common values. That's up to the builder. Personally, I build using the original values. This isn't my first dance with Spaceman builds, so I already have many of these weirdo values in stock.

I'll make the corrections later today.
Title: Re: Spaceman Sputnik II
Post by: digi2t on July 03, 2017, 07:08:28 PM
Vero updated.

Thanks Phil!  :icon_biggrin:
Title: Re: Spaceman Sputnik II
Post by: digi2t on July 04, 2017, 10:55:45 PM
Another update. Couple of resistors were mislabeled, and the BS250 image orientation was wrong way around. Also corrected both filter switch connections. They now reflect what the original does when the toggles are up or down.

(https://s1.postimg.org/wj7rww7jv/Sputnik_II_vero.jpg) (https://postimg.org/image/wj7rww7jv/)

(https://s17.postimg.org/dsbaluf17/Vero_reverse_cuts.jpg) (https://postimg.org/image/dsbaluf17/)

Progress so far on the vero...

(https://s1.postimg.org/yqf4jldq3/DSCF5325_1.jpg) (https://postimg.org/image/yqf4jldq3/)

The sockets are temporary for testing, I'll solder everything in permanent once I've settled on the right transistors. Initial voltage test puts me right in the wheelhouse of the original.  :icon_biggrin:



Title: Re: Spaceman Sputnik II
Post by: digi2t on July 09, 2017, 04:58:16 PM
Well, that's it!! I'm stickin' a fork in this one, it's done.  :icon_biggrin:


(https://s13.postimg.org/v49nx7z77/DSCF5326.jpg) (https://postimg.org/image/v49nx7z77/)

(https://s9.postimg.org/934a4xoaj/DSCF5328.jpg) (https://postimg.org/image/934a4xoaj/)

(https://s12.postimg.org/r33qsyxh5/DSCF5330.jpg) (https://postimg.org/image/r33qsyxh5/)

Works like the original, but I prefer the sound of the 2SB172's though, so I hucked the original into the trash. (Just kidding  :icon_razz:)

I have made some slight changes to the vero. Firstly, I forgot the wire for the bypass LED - (dummy!), and I replaced the 22K (R17) resistor with a trimmer. Different diodes react a bit differently, so the trimmer allows for some adjustment where the detection point is concerned, especially when reversing the polarity. You can set it to 22K before you solder it in, record your initial voltage for reference, and then play with it to set your oscillation envelope.

Here are the verified veros, one with the switch, one without (as per the original). I've also added reversed images with the cuts highlighted.

(https://s24.postimg.org/r7h4sfkn5/Sputnik_II_vero.jpg) (https://postimg.org/image/r7h4sfkn5/)

(https://s24.postimg.org/uia361zy9/Vero_ORIGINAL_reverse_cuts.jpg) (https://postimg.org/image/uia361zy9/)


(https://s24.postimg.org/iqhmhify9/Sputnik_II_vero_diode_switch.jpg) (https://postimg.org/image/iqhmhify9/)

(https://s24.postimg.org/teldgcpxd/Vero_DIODE_SWITCH_reverse_cuts.jpg) (https://postimg.org/image/teldgcpxd/)

I'll get a video of it up soon.


Title: Re: Spaceman Sputnik II
Post by: stringsthings on July 10, 2017, 01:52:08 PM
Awesome !!  I haven't made a vero project in a long while.  ( used to do it all the time )
This would make a great addition to my DIY pedal collection.  Many thanks for your work/efforts!
Title: Re: Spaceman Sputnik II
Post by: digi2t on July 15, 2017, 10:33:07 PM
Video is done.



The overall brightness of the 2SB172's is especially apparent in Drift (oscillation) mode.

What's interesting here is tonight, after staring at the schematic for a while, I suddenly hit me that I had seen that diode feedback oscillation scheme somewhere before.... the Schumann Two Face Fuzz.

(https://s12.postimg.org/nk8t756fd/Two_Face_circuit.jpg) (https://postimg.org/image/nk8t756fd/)

The only difference here is that Schumann added a clamping cap to ground, but the premise seems the same. When I built the Two Face, I found that different clamping cap values dictated the oscillation tone when the signal was fed back. In the original Two Face, the cap values were quite small. In my clone, I found that 1800pF gave the oscillation a much better tonal range. Given that I used different transistors in the Two Face clone, I think that here the cap values may have been a help in getting the oscillation mode into a range that better matched the original.

So, it's kind of late now, but tomorrow, I'm going to try this angle in the Sputnik. Given that I'm not using the same transistors as the original, a clamping cap might be the ticket to adjust the oscillation tone range to better match the original. If so, it might be a decent add-on.

The fun continues...
Title: Re: Spaceman Sputnik II
Post by: Cozybuilder on July 16, 2017, 08:32:42 AM
Great job Dino. Another for the to-do list.
Title: Re: Spaceman Sputnik II
Post by: digi2t on July 16, 2017, 07:51:34 PM
Great job Dino. Another for the to-do list.

Thanks Russ! This one's been quite a bit fun to noodle with.

As I expected, a cap to ground on the anode side of the Ge diode was just what the doctor ordered. What I did was set the two units gain and tone settings to 9 o'clock, both filter switches to the middle position, and nudged up the oscillator voltage until they would self oscillate. My clone was oscillating at a much higher frequency, so I just auditioned caps until the clone was oscillating at the same frequency as the original. It ended up using a 0.1uF cap, which I soldered in. I could probably gone with a 0.12, or 0.15uF, but 0.1uF sounds good to me. The diode reversing switch still works as before, again, with a lower frequency range.

I used the frequency counter function on my DMM, measuring at the HIGH FILTER 1 side of the 39nF cap. Anywhere in the 400Hz to 600Hz zone gets you into the original's oscillation frequency zone.

The oscillation is now not only on par with the original, but also in a much better range high to low. The high end was almost into dog whistle territory!  :icon_lol:


Belay last!!!

The cap to ground was NOT a good idea. After much noodling today, I found that it was a game of diminishing returns. Bigger cap, yes, does tame the oscillation, but it also darkens the original tone. By the time you get to sanity, the top end is too dark. So, the cap is out.

But, using a Ge diode with a low Vf helps. The D9E I used originally measured in at 0.323. Sorting through my bag, I found one at 0.272. I swapped it in, and there's a bit more variety in the jumping octaves, motorboating, and whatnot. At the end of the day, different transistors will yield different results, so socketing is highly recommended.

So that's it. Done.
Title: Re: Spaceman Sputnik II
Post by: bluebunny on July 18, 2017, 03:01:40 AM
So that's it. Done.

(http://upload2.inven.co.kr/upload/2017/06/15/bbs/i14051224868.gif)
Title: Re: Spaceman Sputnik II
Post by: digi2t on July 18, 2017, 10:39:20 AM
So that's it. Done.

(http://upload2.inven.co.kr/upload/2017/06/15/bbs/i14051224868.gif)

My feelings precisely... I can move on to something else now.

(http://upload2.inven.co.kr/upload/2017/06/15/bbs/i14051224868.gif)