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[BUILD] Fritz Euro Teezer VCO
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author [BUILD] Fritz Euro Teezer VCO
We are very pleased to announce availability of the Ian Fritz Euro Teezer Thru-Zero VCO.

The aluminum euro panel design by clarke68 is 18hp- and is very complementary to the euro Threeler VCF design: they look great together!

This is a two-pcb set with all panel components soldered to the panel pcb. (The dual gang tuning pot does require a bit of flying wire assembly. )
The PCB set has been tested and modified a bit from earlier Teezer versions, optimized for 12V.
All analog, all thru-hole.

Please feel free to use the thread for build examples, questions, mods etc-- the updated Ian Fritz build guide is available as a free download from the webstore , along with the synthCube kit BOM that shows our choices for certain options like the matched transistor pair, et al

special gratitude to ian fritz for collaborating with us, and to our beta testers clarke, mike, pete, raph and quincas!

euro teezer vco

This is excellent - so happy to see this in Euro! I'm a huge fan of Ian's designs. Can you provide more information on the dual-gang tuning pot (R12)? I didn't see any information on that in the BOM. Is it a 10-turn, and do you have a recommended part number? Also, about the turn-counting dial - do you have a suggested part number for that? What is a recommended outside diameter?
Thanks, and thanks for bringing this product to the DIY community!
Here's the BOM we are using for first run kits including the multiturn pot and Bourns multi-turn dial P/Ns... these are not inexpensive by comparison with 'average' eurorack controls but we felt that part of what makes Ian's Teezer design unique is that fine tuning initial frequency- so we kept it!

A few other design points--
a) the panel pcb uses alpha 16mm right angle pots and LJE black barrel 3.5mm stereo jacks (like euro klee sequencer) for height consistency
b) ian chose to use a lot of 1/8w metal film thru-hole resistors to save layout space-- they have smaller bodies than their 1/4w evaluate the pcb before deciding on which resistors you want to use.. since the larger body 1/4w resistors will not fit the pad spacing the same as the 1/8w type
c) you have multiple choices for the matched transistor pair-- well documented in ian's build guide
d) full schematics, notes, and PCB stuffing/layout drawings are also in ian's build guide...
Thanks for clearing that up. This is super exciting!
Having some trouble checking out on the SynthCube site. Sent you guys an email about it through the contact form.
yes, we're sorting some checkout issues resulting from recent changes to credit card compliance requirements... thank you for the patience!
the bad producer
Looks great! But surely it's a "multi-turn" pot, not a "dual-gang" (ie stereo) pot? Or have I missed something! hihi
thank you

post edited accordingly smile

need more coffee
could sum1 share a link to the build guide? It wont let me download on the website seriously, i just don't get it
posted here also
I just finished assembling one of these and the kit had another resistor included for R19. The BOM shows 470K and this one was 680K. I'm wondering if that's on purpose? I partly ask because right now it's not working right, I get a rather slow saw (down ramp, is that right) and triangle but no sine.. and neither the init freq or coarse tune knobs affect the frequency. No obvious soldering issues or mis-stuffed parts found yet, I'm done DIY for the night and will pick up tomorrow after studying the schem a bit more.

EDIT to say the way these kits are packed with each component in a bag with the PCB designations printed right there on the bag made this a breeze of a build smile
R19 should be 470K per the latest BOM and schematic from Ian.
Ok cool, the 470K was included along with everything else and it's what I stuffed in there smile
Got one out of two of these calibrated tonight. The issues I ran into earlier were a bad 3280 and I had the Init potiometer wired up wrong. The legs are organized 2, 1, 3 and I had wired them up 1, 2, 3.

Tuning was a bit confusing at first, until I stopped and took a minute about to think what I was doing. I ended up using this process:

Set the coarse and fine tune so it was at 200hz with 0 volts at the CV input.
Apply 1v to the cv input and measure the frequency. Let's say it was 225hz.
Determine the ratio of the two frequencies. 225/200 = 1.125. An octave would equal 1 in this equation, so this tuning is too wide.
Adjust the V/O trimmer, repeat the measurements and calculate the ratio again. If the resulting ratio moved closer to 1 (say 1.100) then the direction I turned the V/O trimmer was correct, if it moved away (say 1.150) then I'd adjusted V/O in the wrong direction.

Repeat these adjustments and measurements until you get a ratio of exactly one (in practice 1.001 or less is pretty good for a VCO).

Given the small adjustments involved you may find it easier to get it close, then repeat the tuning adjustments across multiple octaves with it mixed with a solid digital oscillator and using your ears.

The waveshape trimming was easy, just a matter of having some patience and checking the results at each end of the init trimmer.

I tweaked it a bit with black aluminum knobs from love my switches

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