DIY Build CEM3340 (?) (Noob Question)

[RaphaelLari]

Hey, i’m new in the forum and in diy eletronics as well

So im looking forward to build a synth with the kosmo format and i want to start with the VCO, and for that cem3340 is needed, and i was wondering if it is possible to build it myself.
“But why the hell you would do that?” you ask me.
That’s because i’m Brazilian. What it means is the cem3340 costs BRL 66,76 + taxes which is probably more or less 50% of the price + international shipping.

I had this idea when i was looking the cem3340 documents and manual and it seems simple, but shit, i have no idea.

Btw, the 3340 clone its cheaper but still expensive for a south american

Any thoughts?

[Dud]

welcome to you,
maybe some ways in this thread

Cheap Component Search

if done right, these modules and format wont be that expensive at all. for instance im finishing off an envelope generator now that after panel/pcb the parts would be overall £6/7. stuff like the filter is under £10 and the vclfo is not far off! so please chat parts that relate to all of the modules on this topic!

[RaphaelLari]

thank you! i looked on the thread and searched on ebay and its really cheaper than the other options, but im still looking if it is possible to do build it. I will buy if its no other option hahaha

[analogoutput]

There are no noob questions. There are only questions.

@RaphaelLari

What it means is the cem3340 costs BRL 66,76

Google says 1 BRL = $0.18.

So that’s about $12. SynthCube is charging $15 so that’s not a Brazilian thing…

@RaphaelLari

• taxes which is probably more or less 50% of the price

Well, that probably is

@RaphaelLari

• international shipping

And that.

Anyway, yes, you do need a CEM3340 or the cheaper clone for this design, no way around that. There are other VCO designs that don’t use ICs that cost that much, though they’re either much more complicated circuits or much less capable. Still, if cost is the driving issue, that’s probably the way to go for now.

[Jos]

If you are interested in building a modular system and are on a tight budget, then I can recommend the series of videos by Kristian Blåsol called “Modular In A Week”. This is the accompanying playlist.
He builds all kind of modules and always tries to make them as cheap as possible. He even publishes and shows a spreadsheet with all the prices of the components needed for a particular module.

[Dud]

@RaphaelLari

im still looking if it is possible to do build it.

building the equivalent of a CEM seems complicated to me, otherwise as the others say why not try an oscillator without IC

there is also Sam’s Super Simple Oscillator (which pauses some production problems for a lot of people here) but it has very little component

STUFF - LOOK MUM NO COMPUTER

[RaphaelLari]

I was calculating on the £ price and i didn’t know that were another places selling cheaper.
Pay in dollar its better for sure haha
thank you!

[RaphaelLari]

thanks man will check it out!

[RaphaelLari]

yeah, i thought about this oscilator as well and in the future i was thinking to build a module with several of them like the hundred (and now thousand) oscilator project but in the website there were no schematics, Sam posted it in another place?

[Dud]

yes there is the diagram on the page

[analogoutput]

The SSO can be fun but also can present problems since it uses the transistor in an unconventional way, and it also isn’t something that’s very useful for synthesis — by all means play with it if you want to, but it’s not what you want to build a synth from.

[analogoutput]

That diagram is wrong, unless you’re looking up at the transistor from underneath.

[Dud]

I think it is represented from below with the little legs that we see

and it is true that if it is for a modular project it is not the thing that I would recommend either, but it has the advantage of not being expensive it is especially for that that I proposed it

[RaphaelLari]

I mean not the schematics of the oscilator itself but the proper union of several of then

[Dud]

just connect them together the resistance of 100k acts as a “mixer” between them.

look at the Sam vids about that build

[analogoutput]

In the 1000 osc MegaDrone he uses a 100k pot followed by a series 1M resistor and a 1n4148 diode. Those are connected to an audio amplifier for the output.

[twinturbo]

I followed Sams diagram for the CEN3340 simple circuit. I think I paid £5 each for my chips.

I made up a PCB and panel in KiCad, and had them fabricated by JLCPCB

Think the total cost will be around 12 per VCO

Made a mistake on the trim pot, should be on the daughter board.

Waiting on a couple of components before I can finish it.

Hopefully it will work!!

Will share the files once working

[twinturbo]

Soundtronics may ship to you only £4.28 each.

https://www.soundtronics.co.uk/as3340-voltage-controlled-oscillator-vco-16-pin-dip.html

or the druid may be able to sort you out

https://electricdruid.net/product/as3340-vco/

[twinturbo]

And I built two of these little boards too

https://www.mitchelectronics.co.uk/product/voltage-controlled-oscillator/

VCO.pdf

And by the look of it, if you swap out the 358 for a 324, you get all the IC into one package.

[fredrik]

See here for the exponential converter that’s mentioned briefly in the build document:

Help: A Newbie's Drone Synth

The build instructions for that VCO mention an exponential converter but doesn’t explain how to build one. This article (by the same author) has the schematics: (Kristian Blasol of Modular In A Week fame is currently live streaming a build of the AAC version, and I thought the schematics looked suspiciously similar )