[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 » Mon Aug 11, 2014 7:08 am

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 » Mon Aug 11, 2014 7:44 am

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 » Mon Aug 11, 2014 7:53 am

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 » Mon Aug 11, 2014 7:56 am

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 » Mon Aug 11, 2014 7:56 am

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 » Mon Aug 11, 2014 8:11 am

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 » Mon Aug 11, 2014 8:16 am

This seems to be an interesting design! I hope I can buy a few boards eventually.

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Post by L-1 » Mon Aug 11, 2014 8:31 am

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 » Mon Aug 11, 2014 8:40 am

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 » Mon Aug 11, 2014 9:41 am

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 » Mon Aug 11, 2014 10:52 am

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 » Mon Aug 11, 2014 1:52 pm

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 » Tue Aug 12, 2014 2:06 am

I'm in for one of these :tu:

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Post by horstronic » Tue Aug 12, 2014 3:19 am

Very nice!

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makers
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Post by makers » Tue Aug 12, 2014 1:34 pm

I would also like to build two of these!

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Post by Barcode » Tue Aug 12, 2014 2:01 pm

Single PCB? No wiring? Awesome in my book!

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Post by stereonoss » Wed Sep 03, 2014 1:28 pm

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 » Wed Sep 03, 2014 1:31 pm

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 » Wed Sep 03, 2014 4:04 pm

They require from me a complete system.
As do we! :hihi:

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Post by Stides » Wed Sep 03, 2014 6:42 pm

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 » Wed Sep 03, 2014 10:30 pm

Can't wait for this one!,
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Post by sonicwarrior » Thu Sep 04, 2014 3:36 am

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 » Thu Sep 04, 2014 5:41 am

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 » Thu Sep 04, 2014 5:42 am

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

I already prdered boards for a prototype!

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Post by L-1 » Thu Sep 04, 2014 5:50 am

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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