New project: Dual VCO for Eurorack

[Synthbuilder]

The ASV's VCO circuitry as a 14HP euro module:



Surface mount for the most part but like my other Eurorack projects it's the larger 0805 and SOIC parts.



Builder's Guide should be online towards the end of the week.

http://www.oakleysound.com/DVCO-e.htm

Tony

[Pav]

I see more smd in my future ... the writing is on the wall
Ordered mine though

[Synthbuilder]

I see more smd in my future ... the writing is on the wall

Sadly we are losing quite a few good through hole parts as the world moves towards increasingly smaller electronics. But through hole parts will continue to exist and I'll endeavour to keep the 5U stuff going as long as I can.

That said, I rather enjoy the surface mount assembly process. It takes me about the same time to populate the board. The real bonus though is that the waste is a lot less and there's a lot less solder and flux fumes to deal with. I got Specsavers as part of their get two for one deals to make me a pair of reading specs that are good at four inches distance. These are perfect for SMD assembly. Some folk use these sorts of things:

https://uk.farnell.com/lightcraft/lc177 ... dp/2442795

Probably should try and get some before they sell out.

Tony

[Pav]

I will add these to my next farnell order. With the flanger and sequencer pot board smd work completed i feel I have lost my smd cherry so to speak, and to be fair , confidence has now grown. This is why i was happy to place an additional order.

[tvh]

I got a set of those with the interchangeable lenses from Amazon and they replaced my reading glasses when soldering. The little light is very useful.

[Pav]

The led and lenses headset arrived today and I can confirm my ability to inspect my smd ic soldering has improved considerably. It's cheap and I can use with my prescription glasses.

[Pav]

Hi, Any Hfe value recommendation for BC850 /860 .? .. appears some choices @Farnell

[Synthbuilder]

Any Hfe value recommendation for BC850/860

B or C, it doesn't matter in the D-VCO. Just like the BC550/560s used in the through hole Oakley modules, if it doesn't give the suffix in the parts list then the grade should make no difference.

I'll make them C types in the parts list to save any confusion. I used C types in my prototypes.

Tony

[Pav]

Hi

just to report that I have completed my first build of Dual VCO this afternoon
(1 of 2 pcb sets) and It has been running for 45mins with an Saw1,Pulse2,Tri patch with and without Sync.

Pleased with sound, and happy to recommend it to others.

My soldering was not the best this time so i expected a few problems, but no, only one, which i hope to find quickly.

I have no pulse1 audio output at the moment. saw1 is fine.
i have perused schematic and can see i need to check soldering of pin7 U9 and upstream on main board.
If pin7 has the signal Ill then check pin6 of CN7 connection and then on to checking pot board.

EDIT -- I have no output from comparator U3 pin 7 where im expecting pulse.
I have saw on input pin 5 . but pins 1,2,3 appear to be ok as we have sync working -
can half a comparator fail ? hmmm.
Resistor reflowed U3 reflowed - no joy
- puzzle continues
END EDIT

Ill post audio/video clip something - after i have Is 4.30 too early?

[Pav]

It seemsmain board U3 is ok. It is receiving a 10v from the PW circuit to compare with. Turning the PW1 knob has no effect.
Reflowed the Pot Board PW circuit . and I have the Pulse output working now.!

[whyfarer]

Anyone who's built and using one of these have opinions to share on it? I'm pretty interested but there's not a lot of info out there on it and even fewer examples of how it sounds ... thanks!

[Synthbuilder]

I'm pretty interested but there's not a lot of info out there on it and even fewer examples of how it sounds ... thanks!

Not that many DVCO modules out there to be honest. However, all the sound samples for the other Eurorack Oakley modules on my site use the DVCO as a source. For example, the COTA filter's audio samples use a single DVCO module.

http://www.oakleysound.com/COTA-e.htm

[whyfarer]

Thanks for the pointer! I'll give those other demos a listen