[IN STOCK] L-1 Basic VCO. Eurorack. [Mouser cart p.4]

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L-1
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[IN STOCK] L-1 Basic VCO. Eurorack. [Mouser cart p.4]

Post by L-1 »

http://l-1.su/BasicVCO.html


Finally I had time to work on the VCO. I finished the second prototype and prepared docs for ordering a final prototype.

This is basic VCO because has only basic functions.

Triangle core with sync possibility based on the THAT2180 and OPA2604 chips. Regular TL07* opamp doesn't work here because of high wave amplitude. Limiting wave with diodes as were suggested gives problem with sync. So, only OPA2604 in the core.

VCO range is from 8 Hz to 14 kHz. VCO/LFO switch between timing capacitors. I used 100p and 10n 1% polystyrenes. So LFO range is 100 times slower than VCO.

No expo converter here because THAT2180 has expo responce. CV circuit is tempereture compensated with two 2K tempco resistors.

I used BCM847BC matched pair for sinewave circuit.

I used LM4040 precise voltage source for offset voltages to minimize pitch flow. I tested during 4 hours - pitch was stable in range +- one cent.

I installed Schmitt trigger on the sync input. So any wave is good for sync.

I was able to achieve cent-by-cent tracking as on the first prototype.

[video][/video]

The VCO - left board the core, right board - saw, sine, PWM circuits:

Image

Image
ImageImage
Last edited by L-1 on Mon Mar 09, 2015 8:32 am, edited 6 times in total.
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djpasica
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Post by djpasica »

why :despair:
i think there is a lot of basic modules (osc)
IMHO

if it will not cost :75:
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Post by andrewF »

djpasica wrote:why :despair:
The joy & satisfaction of DIYing his own VCO and seeing it work :love:
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Post by L-1 »

djpasica wrote:why :despair:
i think there is a lot of basic modules (osc)
IMHO

if it will not cost :75:


What for example? For DIY Euro, not digital, without timers or logic. Classic analog design.

1. 258J from Thonk.

2... :hmm:
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Randy
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Post by Randy »

I could see this being handy for smaller systems or adding polyphony. Make it 4hp and I'll buy it!

Randy
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Post by andrewF »

L-1 wrote:
djpasica wrote:why :despair:
i think there is a lot of basic modules (osc)
IMHO

if it will not cost :75:


What for example? For DIY Euro, not digital, without timers or logic. Classic analog design.

1. 258J from Thonk.

2... :hmm:
2... this one? :razz:
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CJ Miller
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Post by CJ Miller »

This seems to be an interesting design! I hope I can buy a few boards eventually.
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L-1
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Post by L-1 »

Yes andrewF.

The second reason why I make this - it's local musicians. They require from me a complete system.
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Post by andrewF »

L-1 wrote:Yes andrewF.

The second reason why I make this - it's local musicians. They require from me a complete system.
Pretty lucky DIYers in your town 8_) .
the locals here in P-town have to endure my half-assed insanity :spin:
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Post by livefreela »

i would frame that proto photograph for my wall EDIT now it's my computer desktop. awesome. l-1, way to be man, way to be!
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Post by Reality Checkpoint »

Well I very much like it and applaud the classic analog design.

And I will no doubt end up with one or two in my system.
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Post by bkbirge »

andrewF wrote:
L-1 wrote:Yes andrewF.

The second reason why I make this - it's local musicians. They require from me a complete system.
Pretty lucky DIYers in your town 8_) .
the locals here in P-town have to endure my half-assed insanity :spin:
Don't sell yourself short man, there's nothing half-assed about your insanity.

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cane creek
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Post by cane creek »

I'm in for one of these :tu:
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Post by horstronic »

Very nice!
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makers
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Post by makers »

I would also like to build two of these!
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Post by Barcode »

Single PCB? No wiring? Awesome in my book!
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Post by stereonoss »

L-1 wrote:Yes andrewF.

The second reason why I make this - it's local musicians. They require from me a complete system.
+1
I have Quad VCA/Mixer and Tube VCA from you ) it sounds perfectly and i will buy system complete from L-1 Corporation )))
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Post by stereonoss »

L-1 wrote:Yes andrewF.

The second reason why I make this - it's local musicians. They require from me a complete system.
+1
I have Quad VCA/Mixer and Tube VCA from you ) it sounds perfectly and i will buy system complete from L-1 Corporation )))
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Post by euromorcego »

They require from me a complete system.
As do we! :hihi:
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Post by Stides »

Looks nice to me. Reasonable size to feature ratio, and seems to have a minimal component count. Always comes to price and availability, but your stuff always is reasonable.
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Post by synthcube »

Can't wait for this one!,
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Post by sonicwarrior »

Would have been nice to an attenuator for the PWM input. I always need an attenuator plus offset there.

FM is linear I hope?

Only 3 trimmers look like fun to calibrate. I'm always intimidated by the many trimmers on most VCO PCBs. :oops:

Edit: Does it run with +/- 15 V? Would be fun to squeeze this into a single width MU panel although it would mean panel wiring.
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Post by L-1 »

sonicwarrior wrote:Would have been nice to an attenuator for the PWM input. I always need an attenuator plus offset there.

FM is linear I hope?

Only 3 trimmers look like fun to calibrate. I'm always intimidated by the many trimmers on most VCO PCBs. :oops:

Edit: Does it run with +/- 15 V? Would be fun to squeeze this into a single width MU panel although it would mean panel wiring.

No place for PWM attenuator sorry.

No linear FM, only exp. 2180 chip has exp response, and needs another matched transistors pair for linear.

About 15V. It can I think but some resistors changes will need. There is 10V source for offset voltages.

I plan to make more advanced dual osc later. I will include there lin FM and many other possibilities.
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Post by L-1 »

synthcube wrote:Can't wait for this one!,

I already prdered boards for a prototype!
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Post by L-1 »

Only 3 trimmers look like fun to calibrate. I'm always intimidated by the many trimmers on most VCO PCBs. oops
Really I added fourth. Will be:

- v/oct
- offset
- saw symmetry
- sine symmetry
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