Building my first VCO

Hello!

I just got a power supply from AI Synthesis (DIY Eurorack Power Supply How To Build Guide) and I’m putting that together soon. Pretty simple for someone like me with limited experience. I’m starting to gather a list of items for the LMNC VCO the build with the Square Out w/ PWM CV (STUFF - LOOK MUM NO COMPUTER).

This might be annoying but I would appreciate the help. Before I purchase I have a list with links below and was wondering if anyone is willing to look through it and let me know if I have any of it wrong.

1x – Strip Board (Big StripBoard 110x93mm (Copper))

1x – Trimpot (10K OHM TRIMMER POTENTIOMETER CERMET 25 TURNS 3296W)

3x --100k Potentiometer A100k (9mm Alpha Potentiometer - AI Synthesis) w/knobs

1x – 16pin IC Socket (16 pin DIP IC Socket Adaptor Solder Type)

2x – 8pin IC Socket (8 pin DIP IC Socket Adaptor Solder Type)

2x – 470R Resistors (470 OHM 1/4W 1% Metal Film Resistor Royal OHM Top Quality)

1x – 620R Resistor (620 OHM 1/4W 1% Metal Film Resistor Royal OHM Top Quality)

1x – 1.8k Resistor (1.8K OHM 1/4W 1% Metal Film Resistor Royal OHM Top Quality)

1x – 5.6k Resistor (5.6K OHM 1/4W 1% Metal Film Resistor Royal OHM Top Quality)

2x – 10k Resistor (10K OHM 1/4W 1% Metal Film Resistor Royal OHM Top Quality)

1x – 24k Resistor (24K OHM 1/4W 1% Metal Film Resistor Royal OHM Top Quality)

4x – 100k Resistor (24K OHM 1/4W 1% Metal Film Resistor Royal OHM Top Quality)

1x – 470k Resistor (470K OHM 1/4W 1% Metal Film Resistor)

1x – 1.5m Resistor (1.5M OHM 1/4W 1% Metal Film Resistor Royal OHM Top Quality

1x – 0.01uF Capacitor (0.01uF 50V Ceramic Disc Capacitor)

1x – 0.001uF Capacitor (0.001uF 50V Ceramic Disc Capacitor)

1x – AS3340 (Alfa AS 3340 VCO IC voltage controlled oscillator chip)

2x – TL072 (TL072 LOW NOISE J-FET DUAL OP-AMP IC)

5x – Jack Sockets (6.35mm 1/4" Stereo Phone Jack)

1x – 8pin Double Row pin header (2x8 Pin 2.54mm Double Row Pin Header Strip)

1x – Ribbon Cable (Eurorack Power Cable - Modular Synthesizer Accessories AI Synthesis)

I tried to look through a lot of the info here to get this list together and I’m sure I still have half of it wrong haha. As the saying goes “Don’t be scared to try it.” I’m kind of scared to try it but I’m doing it anyway.

Thanks in advance everyone!

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You want linear taper pots, not audio taper (B100k, not A100k).

AI’s price on the 3340 is good but you can get the pots cheaper at Tayda, and $5 for a single power cable is highway robbery. Synthcube charges $1.09 for the same, unfortunately they charge more for 3340s but depending on postage they might work out better. Or you can buy ribbon cable and IDC connectors from Tayda and make your own for under a buck a piece. It’s not hard, especially if you have a vise, but it can be done with pliers.

Added: I suggest a shrouded box header rather than a plain double pin header for power. Also, you’ll want bypass caps (a 100 nF on each power pin of each chip, and a couple of 10 µF near the power header). Sam leaves those off the stripboard layouts but you should add them. I also recommend a couple of 1N5817 Schottky diodes for power reversal protection.

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The resistors you list are all 1/4 Watt. I think you can get away with 1/8 Watt given the application. They may be cheaper, otherwise I would keep the 1/4 W types. Do you need stereo jack sockets or would single channel sockets do as well?

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Resistors are a penny a piece at Tayda, 1/4 W or 1/8 W.* I use 1/4 W. And that’s the jack I use, they don’t have any good mono jacks for less and it fits the footprint on Sam’s PCBs.

* Actually $0.012 for 1/4 W, $0.01 for 1/8 W.

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Great info! I was unsure about the pots (A or B) and thanks for linking them at Tayda. I was also unsure about how to get power so I was taking a bit of a guess with the pin header. Looking at my power supply, it has a 10pin. Looking synthcube I can get both the ribbon and the shrouded box header there! Helps a great deal. I primarily make a lot of cable at work (different type of camera connectors) so I’ll eventually learn to make my own ribbon.

Thanks @Jos and @analogoutput for some clarification on resistors and jacks. I was iffy on whether not I was all wrong, but it wouldn’t mess me up if I went either way on those?

A lot of the small components I plan to order bulk in case they can be useful for future projects.

Thanks for the power suggestions too! Glad to see I’m not terribly off on my list. I appreciate the look through

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Shrouded headers at Tayda 10 Pin Box Header Connector 2.54mm

100 nF ceramic caps 0.1uF 50V Ceramic Disc Capacitor

10 µF electrolytic caps 10uF 100V 105C JRB Radial Electrolytic Capacitor 6.3x12mm

Schottkys 1N5817 Diode Schottky 1A 20V

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Buy some assorted multi packs on ebay of…

1/4W Resistors
Ceramic Caps
Small Electrolytic caps.

Makes much more economic sense and gets you set up for a lot of the projects you may end up doing.

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eBay in the US is quite different from eBay in the UK, I think, in terms of what is available and from what sort of vendors. Amazon I think is better for this sort of thing, if only because returns are less of a hassle if what you’re sent turns out to be crap. And the component kits I’ve seen for sale on either site all seem to come from sketchy or unknown vendors, with prices worse or not a lot better than Tayda’s. Worse if you take into account they tend to have a number of values you will never use. And I have more confidence in Tayda’s components.

I have a resistor kit and a ceramic caps kit from Amazon, both bought because I needed one value in a hurry and it made more sense to buy a kit than to order a single value from Mouser. Very flimsy thin leads on the resistors, probably okay for building but questionable for breadboarding. The caps seem okay.

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Tayda + waiting a bit is usually my method. I have bought things from amazon if not found at tayda or need faster. I can usually just wait though.

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