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211
Joined: Jul 18, 2006 Posts: 50 Location: Marseille - France
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Posted: Mon Feb 19, 2007 4:36 am Post subject:
LFO Delay |
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Hi all,
Does anyone build this LFO delay with success ?
I just built it, with BC547/557 trannies and +15-15 powered, and it don't work at all...
I can see C2 1uF caps discharge on gate, but nothing after R2.
My LFO (initially +5/-5v) output voltage is stuck to +0,5/-0,5 but don't raise to +5/-5 when C2 is discharged..
Any idea ? Do I need to change R2 resistor value to fit with my power supply or BC557 properties ?
thanks ! |
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andrewF
Joined: Dec 29, 2006 Posts: 1176 Location: australia
Audio files: 4
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Posted: Mon Feb 19, 2007 8:02 am Post subject:
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This is one of Kunii San's (aka Masa 921), a master of minimal circuit design.
I built it a few years back, no probs (not that I remember )
I think it was meant to be an add-on for his LFO.
The transistors are nothing special -I've used C1815(npn) and A1015(pnp) for nearly every CGS circuit with no trouble or mods(other than different pinout). Also I used -15V with this.
The synth, it lives in, is in storage now so I can't get to it to check anything.
If you're sure all connections and orientations are good, I guess R2 is the place to start experimenting.
Masa921 is not much good at English but if you are stuck I can check with the guys at Japanese synth-diy for some hints.
I can't resist posting this pic - Masa921 microVCO, no chips just 5 transistors and 2 FETs, V/Hz and V/oct control and it sounds awesome, very meaty. Thats the whole cct in a blob of goop. He bought it to a diy meeting, hooked it up and started playing. everyone was pretty stunned by the quality (and the size)
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funkyfarm
Joined: Jan 21, 2007 Posts: 583 Location: France
Audio files: 3
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Posted: Mon Feb 19, 2007 8:33 am Post subject:
Re: LFO Delay |
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211 wrote: | Hi all,
Does anyone build this LFO delay with success ? |
This is a cheap design as it obviously doesn't reset your LFO waveform.
So, after delay time being elapsed, the LFO doesn't start from zero... |
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211
Joined: Jul 18, 2006 Posts: 50 Location: Marseille - France
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Posted: Mon Feb 19, 2007 8:57 am Post subject:
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This design is the same as MC202 LFO . I connected my LFO in the same way.. I checked trannies pinout with eagle before assembly..
Now, as andrewF has already built it, I m sure that design may works..
I probably missed something... |
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211
Joined: Jul 18, 2006 Posts: 50 Location: Marseille - France
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Posted: Mon Feb 19, 2007 3:31 pm Post subject:
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that's ok, it works fine ! ( was a bad connection ) |
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blue hell
Site Admin
Joined: Apr 03, 2004 Posts: 24079 Location: The Netherlands, Enschede
Audio files: 278
G2 patch files: 320
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Posted: Mon Feb 19, 2007 6:43 pm Post subject:
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211 wrote: | that's ok, it works fine ! ( was a bad connection ) |
Makes sense, good you found it _________________ Jan
also .. could someone please turn down the thermostat a bit.
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sneakthief
Joined: Jul 24, 2006 Posts: 569 Location: Berlin
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Posted: Tue Feb 20, 2007 5:07 am Post subject:
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andrewF - I was looking through Masa921's site and couldn't find the schematics for the microVCO. Are they available online anywhere?
thanks! _________________ Sneak-Thief - raw electrofunk |
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211
Joined: Jul 18, 2006 Posts: 50 Location: Marseille - France
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Posted: Tue Feb 20, 2007 6:08 am Post subject:
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http://masa921.hp.infoseek.co.jp/synth2.htm
But there's no schematics..
It's Korg MS 10/20/50 design I guess.
2 2SK30 FET / 2SA733 2SC945 transistors.
Expo converter is 2SC1583 based, Volt/oct & Volt/hertz control and output easily tri and square signals.
Does anyone test this design ? Is it stable enough ? |
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andrewF
Joined: Dec 29, 2006 Posts: 1176 Location: australia
Audio files: 4
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Posted: Tue Feb 20, 2007 6:56 am Post subject:
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Masa921 used some different transistors for this design. I have no idea how you would go with substituting, the FETs are probably the fussiest.
There are some amazing pics on the link above provided by 211- why use circuit boards when you have a blob of goop?
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sneakthief
Joined: Jul 24, 2006 Posts: 569 Location: Berlin
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fonik
Joined: Jun 07, 2006 Posts: 3950 Location: Germany
Audio files: 23
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Posted: Tue Feb 20, 2007 2:55 pm Post subject:
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oha, these transistors seem very exotic to europeans, i think. i bet they are hard to find! _________________
cheers,
matthias
____________
Big Boss at fonitronik
Tech Buddy at Random*Source |
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23isgood
Joined: Nov 18, 2006 Posts: 236 Location: San Francisco, CA bay area
Audio files: 13
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Posted: Tue Feb 20, 2007 4:05 pm Post subject:
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Wow nice! So does this micro VCO perform as well as a typical VCO? |
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23isgood
Joined: Nov 18, 2006 Posts: 236 Location: San Francisco, CA bay area
Audio files: 13
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Posted: Tue Feb 20, 2007 8:15 pm Post subject:
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What does the upward pointing black arrow supposed to go to? The one labeled "BIAS"? Is this supposed to be connecting to -12v? Will some resistors be enough to take +-15v down to +-12v?
thanks
pete |
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andrewF
Joined: Dec 29, 2006 Posts: 1176 Location: australia
Audio files: 4
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Posted: Wed Feb 21, 2007 12:19 am Post subject:
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Hi
I was impressed with the sound of this cct but i only heard it for a few minutes.
doubt it will be as stable as a typical VCO, no temperature compensation for a start. Maybe if you used the V/hz input it would be okay.
i suspect the reason the entire cct is built into a little compact blob is so all the transistors can warm up to the same temp and attain some stability, like the EFM chip heater VCO perhaps.
it is a very basic cct, don't expect too much from it. If you already have one or more wizzbang VCOs, this would be a good supplement.
it runs on +12V, +6V and Gnd.
Generally, it would be better to use 7812 and 7806 voltage regulators rather than resistors (with resistor dividers - as the current increases, the voltage changes).
That said, if you are breadboarding, try a resistor divider, it might prove interesting...or not |
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23isgood
Joined: Nov 18, 2006 Posts: 236 Location: San Francisco, CA bay area
Audio files: 13
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Posted: Wed Feb 21, 2007 12:37 am Post subject:
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Well I have plenty VCO's but I really want to build a small compact synth that is portable and this VCO would be a nice addition. With a few pic modules it could happen.
thanks
pete |
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janvanvolt
Joined: Nov 24, 2005 Posts: 285 Location: Mainz, Germany
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Posted: Wed Feb 21, 2007 11:01 am Post subject:
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fonik wrote: | oha, these transistors seem very exotic to europeans, i think. i bet they are hard to find! |
the 2SA and 2SC types are sold by reichelt
the 2SK is sold by banzai.
just ordered mine ...
just as of the design, do i get this right:
- LIN CV jack in
- HARDSYNC jack in
- Oct/V CV jack IN
- VCO jack out
- Pot for COARSE ? (below Oct/V)
- pot for LIN CV
anything i missed ? |
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fonik
Joined: Jun 07, 2006 Posts: 3950 Location: Germany
Audio files: 23
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Posted: Wed Feb 21, 2007 11:49 am Post subject:
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okay - not exotic. _________________
cheers,
matthias
____________
Big Boss at fonitronik
Tech Buddy at Random*Source |
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etaoin
Joined: Jun 30, 2005 Posts: 761 Location: Utrecht, NL
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Posted: Wed Feb 21, 2007 12:18 pm Post subject:
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Quote: |
the 2SA and 2SC types are sold by reichelt
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You might not know this, as you are in Germany, but Reichelt have a minimum order of 150 euros outside of Germany. So they're actually very expensive just to get a couple of trannies. |
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janvanvolt
Joined: Nov 24, 2005 Posts: 285 Location: Mainz, Germany
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Posted: Wed Feb 21, 2007 12:48 pm Post subject:
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Etaoin wrote: |
You might not know this, as you are in Germany, but Reichelt have a minimum order of 150 euros outside of Germany. So they're actually very expensive just to get a couple of trannies. |
Well. If somebody want's to do a groupbuy, i can handle this. |
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andrewF
Joined: Dec 29, 2006 Posts: 1176 Location: australia
Audio files: 4
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Posted: Wed Feb 21, 2007 3:47 pm Post subject:
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Quote: |
- LIN CV jack in
- HARDSYNC jack in
- Oct/V CV jack IN
- VCO jack out
- Pot for COARSE ? (below Oct/V)
- pot for LIN CV
anything i missed ? |
Looks good
The BJT transistors are just AF complementary npn/pnp types, probably not much different to 547/9s or whatever you normally use in synth ccts.
In my experience FETs can be fussier. |
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the19thbear
Joined: Apr 19, 2007 Posts: 150 Location: denmark
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Posted: Mon Apr 23, 2007 4:36 am Post subject:
micro vco Subject description: micro vco |
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any schematics for the microvco? i checked out the website and it was in chinese i'm a newbie so i need some help-- |
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andrewF
Joined: Dec 29, 2006 Posts: 1176 Location: australia
Audio files: 4
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