[sdiy] Digital Oscillators

[Mark Smith]

thanks, you are right I am a design engineer. The design uses no tempco parts, all standard 0805 parts + standard NPN and PNP SOT-23 transistors. The whole ladder and current sources are made from dual SMD parts from Rohm. The only odd part is the 2SK30 for the oscillator follower.

I was testing the water to see what kind of interest there was. I may be tempted to take things further and make it more DIY friendly - although I don't want to upset anyone by doing so.

My whole intention was to build something as close to the original, but bypass the CV VCO bit. I just wanted to build and play without any setting up. I have built two so far - theres approx 80 UKP of bits each + plus the custom metalwork and front panel. Cheap compared to the real thing - and more flexible.

Not sure if I did sell what I would prefer, pre-programmed PIC is a definite - theres over a year of work in the project.

Will keep you posted with any further developments.

mark

> -----Original Message-----
> From:	Sowa Roman [SMTP:Roman.Sowa at upc.com.pl]
> Sent:	Thursday, January 10, 2002 11:29 AM
> To:	'Mark Smith'
> Cc:	'synth-diy at dropmix.xs4all.nl'
> Subject:	RE: [sdiy] Digital Oscillators
> 
> Just want to tell how impressed I am with your 303 clone.
> Looks like you design hi-tech stuff for a living.
> I may be interested in getting one set of boards for it.
> 
> Do you use any hard to find parts like SMD tempcos
> or unusual dual transistors? What size do you use? 0805?
> Is it possible to get PIC firmware, or should I buy programmed
> chip from you? Can I have the PCB files and make it locally
> or you'd prefer to sell me boards?
> 
> Roman
> 
> ""-----Original Message-----
> ""From: Mark Smith [mailto:Mark.Smith at pace.co.uk]
> ""Sent: Wednesday, January 09, 2002 5:00 PM
> ""To: 'synth-diy at dropmix.xs4all.nl'
> ""Subject: [sdiy] Digital Oscillators
> ""
> ""
> ""Hi,
> ""
> ""been synth DIYing for ages, but only recently joined the 
> ""group - Thanks Trev.
> ""
> ""I've spent the last year playing around and have completed 
> ""yet another 303 type clone. Unlike others I have seen I have 
> ""chosen to bypass the Midi - CV - VCO. The result is a single 
> ""chip ( PIC )  midi to DCO. Although it has been designed to 
> ""replace the original oscillator in a 303 it has many other uses.
> ""The circuit is pretty close to the original, other than the 
> ""level detect/schmitt bit is done by the micro. The 
> ""exponential current source is programmable - so as to keep 
> ""the amplitude constant. Thus I have a digitally controlled 
> ""oscillator which includes many of the original parts, but 
> ""keeps in tune. The design is entirely SMD, but for the J-FET 
> ""and Caps on the oscillator. If anyone is interested I could 
> ""re-lay and possibly get some boards made. Adding triangle / 
> ""sine wouldn't be a problem.
> ""
> ""pictures of my clones are at  
> ""http://www.meadowfield.freeuk.com/synth/synth2.html
> ""
> ""mark
> ""
> ""
> ""
> ""
> ""
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> 
> 
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