[Fabbed Run coming] Electric Druid VCLFO 'Modulation Druid'

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frequencycentral
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[Fabbed Run coming] Electric Druid VCLFO 'Modulation Druid'

Post by frequencycentral » Tue Jan 03, 2012 5:44 pm

Update 15th May 2013:

Tom and I are working on a new fabbed PCB for this project. This will be a single PCB that can either be built as a simple or complex version. Options for 16mm or 9mm pots. I'll also be offering acrylic panels: 10HP for the complex version, 4HP for the simple version. I'm thinking of going with yellow acrylic, so the red LFO LED behind it will glow orange, and the blue Sync LED will glow green. The new PCBs should be available in about 6 weeks.


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Update 17th April 2012.

Ok, people are ordering 'Recycler' bundles and asking if they can order the 'Modulation Druid' at the same time, so I'm gonna order 30 more PICs from Electric Druid and I'm throwing it open for a 2nd run, there will be 30 in the run, even if it means I'll be doing nothing but etch PCBs for the next month!

Each bundle contains the basics that you need to build the 8 knob version:

- Main PCB
- CV PCB
- TAPLFO2 PIC
- 20MHz crystal
- 4 x 50k trimmers

....which is £30 GBP including shipping. Paypal GIFT to:

rickholt22 AT hotmail DOT com

12HP 'VCLFO' front panel for 8 knob version is £15.

Please include your forum name as well as your full address in your payment, together with exactly what you're ordering, helps me keep track...


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(Original opening post, for posterity)

I snagged a couple of these chips a while back and am working through building them into a couple of modules and creating a PCB layout.

http://www.electricdruid.net/index.php? ... cts.taplfo

Here's a base schematic for the modular version:

http://www.electricdruid.net/images/lfo ... cuitV1.gif

I don't see a benefit to having an output level control on a LFO within a modular system, so I'm using a fixed resistor there.

I'm going to add a pot for the Wave Distortion, which is kinda a pulse width control.

Also, I'm going with rotary switches instead of pots for the Waveform and Multiplier functions, as per the PDF:

http://www.electricdruid.net/datasheets ... asheet.pdf

So I'm wondering if it would be worthwhile adding CV inputs for the Waveform and Wave Distortion features? Might either be way cool, or esoterically rarely used.

Any thoughts out there in Wiggleand?
Last edited by frequencycentral on Wed May 15, 2013 10:02 am, edited 6 times in total.

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Post by diophantine » Tue Jan 03, 2012 6:05 pm

If you haven't seen it yet, Doug Slocum's TTLFO (MU) and Modulation Orgy (Euro) use this and have VC on all the inputs, etc. The CV is great to have. There's also an Output Level CV input, which is nice (basically a VCA controlling the output).

http://www.steamsynth.com/m_TTLFO.aspx
http://www.steamsynth.com/e_ModulationOrgy.aspx

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Post by goiks » Tue Jan 03, 2012 6:20 pm

i have a couple of version 1 chips on hand i'm happy to give away to a good home as it seems my diy time has completely evaporated since i started making cases.
Last edited by goiks on Tue Jan 10, 2012 7:16 pm, edited 2 times in total.
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frequencycentral
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Post by frequencycentral » Tue Jan 03, 2012 6:21 pm

No I hadn't seen that, thanks for the link. That's a nice implementation of the features. Great idea re the VCA too. I guess I'll build mine to be similar. I'll post a layout once I've done the headwork.

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Post by meatcliff » Tue Jan 03, 2012 8:39 pm

My favorite LFOs... so easy to mix and match inputs as desired, tons of options and it "sounds" (you know what i mean) awesome.

I've built a few of the first version he had published, but there's a bit of stepping on the lowest frequencies... i just run it through a slew module for that stuff.

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Post by glitched01 » Fri Jan 06, 2012 6:25 pm

I agree with meatcliff--the most fun I've had with an LFO.

The VC waveform and distort are useful; the VC freq isn't as cool as it could be because the range is pretty limited. If you don't care about it not reaching the audio range, then it may be useful.

I built one "deluxe" version and am going to build another, simpler version.

There's no reason not to build at least one.

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Post by frequencycentral » Fri Jan 06, 2012 6:53 pm

Yeah, I'm gonna do the same - simple 4 knobber first, then an 'orgy' version.

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Post by Reese P. Dubin » Sat Jan 07, 2012 1:38 am

Breadboarded the Tap Tempo version yesterday.
simple and wicked

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Post by frequencycentral » Sun Jan 08, 2012 10:11 am

So, I think I've got my 'simple as it gets' layout sorted, I'll post it once it's tidied up a little.

Now I'm thinking about the complex version. How are folks implementing CV of all the features? Summing amps?

I'm going to use half a LM13700 to have control of the output level, and wondering of any useful application for the other half of the chip?

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Post by Reese P. Dubin » Sun Jan 08, 2012 10:32 am

There is a CV circuit example in the data sheet for one of the chips. Half a 074 and a bunch of 100k, dead simple.

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Post by frequencycentral » Sun Jan 08, 2012 10:51 am

Oh yeah, silly to have missed that. :doh:

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Post by frequencycentral » Tue Jan 10, 2012 6:55 pm

^^^

Ok, my confusion stemmed from me having two different versions of the chip, 1 x VCLFO 9D and 2 x TAPLFO2. The data sheets differ too of course. Had a little look at the Modulation Orgy, which would appear to be based around the TAPLFO2 version of the chip. So.........I've designed two PCBs:

Main PCB:

Tempo, Multiply, Waveform, and Distort knobs
Ext sync input
Clock output
LFO output
Tempo LED
Output LED
Provision of 10 pin header
Built in 78L05 5v source
Additional pad for expansion (see below)
Provision for 3 pin power header to CV PCB


Pretty much straight off the data sheet, except I've set the Level to maximum (though I've left a pad for external control) and set up a Distort knob. Although I see the benefit of having VCA control or at least CV control of the level, I've got enough DC coupled VCAs elsewhere.......

So, the main PCB can be used as a stand alone LFO which will fit behind a 4hp or 6hp Euro panel. Here's the clincher: I've laid out the main PCB in such a way that it's really easy to hook it put the the second PCB via an 8 way ribbon cable. The four pots on the main board can have their lug 2's connected to the second PCB, and there is a jumper to select either 5v to lug 3's for the stand alone LFO version, or 15v to lug 3's for the 'Modulation Orgy work-a-like' version.

The second (CV) PCB includes:

Pads for connections to Main PCB
Tempo CV input and amount pot
Multipy CV input and amount pot
Waveform CV input and amount ppot
Distort CV input and amount pot
Provision for 3 pin power header to Main PCB


It's based on the VCLFO datasheet page 6 for 1v/oct CV inputs (x4).

Using both PCBs together will give pretty much all the features of a Modulation Orgy and would squeeze everything onto a 12hp Euro panel if you have dainty little finger like me (!).

Both PCBs are the same size, dimensions are 71mm x 54mm. Pots are mounted along the 71mm edge. Pot lugs 2 are 18mm apart. I'm using 16mm Alpha pots.

I've just etched a pair of PCBs so I'll be verifying them over the next few days, then I'll post the layouts. I'll be offering sets to anyone who wants any. It also occured to me that it might be worth worth me splashing out on a tube of 30 x TAPLFO2 chips (the minimum order from Electric Druid)if there's enough interest, so I could put together some little kits which would include:

Main PCB
CV PCB
TAPLFO2 chip
20 MHz crystal
4 x 50k 6mm top adjust trimmers (to set the CVs for 1v/oct)


I'd need at least 10 interested parties before I could consider buying in the chips. Any interest?

BTW, examples of my PCB work can be seen here: viewtopic.php?t=49355

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Post by fivesteppath » Tue Jan 10, 2012 7:19 pm

[video][/video]

^This guy built one for his system. Bottom row, 3rd module from the left.

Always wanted to build one myself.

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Post by DGTom » Tue Jan 10, 2012 7:33 pm

frequencycentral wrote: I'm going to use half a LM13700 to have control of the output level, and wondering of any useful application for the other half of the chip?
use both OTAs as a crossfader & fade between normal & inverted polarity of the LFO out, that way you have CV control of how much & where it wiggles.

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Post by frequencycentral » Tue Jan 10, 2012 7:41 pm

DGTom wrote:
frequencycentral wrote: I'm going to use half a LM13700 to have control of the output level, and wondering of any useful application for the other half of the chip?
use both OTAs as a crossfader & fade between normal & inverted polarity of the LFO out, that way you have CV control of how much & where it wiggles.
Nice idea.......but.......feature creep......that can be done externally, it's modular after all. :love:
frequencycentral wrote: Although I see the benefit of having VCA control or at least CV control of the level, I've got enough DC coupled VCAs elsewhere.......
.......and would add a whole other layer of complexity.

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Post by DGTom » Tue Jan 10, 2012 7:57 pm

sorry, missed the part where you dumped the VCA, was just an idea to use part of an IC & take up no extra panel space :despair:

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Post by diablojoy » Tue Jan 10, 2012 9:03 pm

definitely very interested
if you do a run
i will take 4 at least
It probably wont happen today but if it does it definitely wont go smoothly.

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Post by iopop » Wed Jan 11, 2012 2:35 am

Having a hard time understand which chip you are designing for? The VCLFO or the Tap Tempo LFO ?

I'm be interested in a PCB for the VCLFO so I can finally use that chip I have in my drawer. Would love to see a generic PCB that could be used for both VCLFO and VCADSR chips.

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Post by frequencycentral » Wed Jan 11, 2012 7:23 am

I'm using the Taplfo2 chip, which has a few more functions than the vclfo. The vclfo should work on this pcb though, with a few exclusions.

The vcadsr is too different to work on this pcb, bit I'll certainly do a layout for it. Just need the chip. Anyone want to do swapsies?

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Post by Luka » Wed Jan 11, 2012 11:51 am

I have a pair of these heavily modded based of blue lanterns pcb. Waveform select cv is realy cool - slew is really handy too. Conditioning cv was a bit of a challenge

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Post by brother303 » Wed Jan 11, 2012 5:27 pm

Hi,

cool stuff! Put me down for two pcb/chip sets,please.

:tu:

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Post by arsonus » Thu Jan 12, 2012 6:22 am

if you do a run i will take 2 pcb/chip sets, please.

:tu:

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Post by frequencycentral » Thu Jan 12, 2012 7:34 pm

diablojoy wrote:definitely very interested, if you do a run, i will take 4 at least
brother303 wrote:cool stuff! Put me down for two pcb/chip sets,please.
arsonus wrote:if you do a run i will take 2 pcb/chip sets, please.
Ok, I'll get the PCBs built and verified ASAP.

Probably need just a couple more takers before I can justify pulling the trigger for 30 chips.

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Post by machum » Thu Jan 12, 2012 7:41 pm

Please count me in for 2 pcb/chip sets also.

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Post by slowalan » Fri Jan 13, 2012 6:35 am

Put me down for 1 pcb/chip set please
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