extreme newbie questions on xavax.com/efm's cookbook

[Happy Harry]

Hail Newbies !!! (inline)


>From: Egbert Teeselink <egbert at gmx.co.uk>
>To: synth-diy at node12b53.a2000.nl
>Subject: extreme newbie questions on xavax.com/efm's cookbook
>Date: Thu, 4 Jan 2001 21:54:02 +0100 (MET)
>
>hello, it's us again: the ultimate Synth-DIY newbies (!)
>
>well, we finally soldered something, a VCO to be exactly. we took some
>simple schematics from http://www.xavax.com/efm/cbook/vco5.html
>the one using the LM13700 I.C.
>
>but of course we have got some questions:
>
>1) at several places it shows little triangles at the ends of a wire, does
>this mean you have to connect them to the positive side of the power
>supply?

If they point "up" they go to positive supply... down to negative supply.
>
>2) the same goes for the ground/mass symbols, should these be connect to
>the negative end of the power supply?

Ahh... NO.  These have a Bipolar supply.  Think of two 12V batteries
in series. The Plus of the top one is +12V... the wire from the
minus of the top battery to the plus of the bottom battery is the
Ground (or more common... COMMON) terminal.  The minus of the bottom
battery is -12V.
>
>3) we decided to replace the part connected to the base of the leftmost
>transistor by just one wire with a +V as control voltage? (it's because we
>just want to cook an osci that creates sound, we do not really need a 
>complete
>keyboard incl. pitchbend-wheels or something.)

I would not do that... use the components labeled "Init" as shown to
control the frequency. You could eliminate (for now) the 1V/oct
components and the 22K resistor (CV input) and trim pot. These are
needed to make the oscillator  track a keyboard, not just to make
a noise...
>
>4) what voltage (from power supply) should we use at all anyway on the
>whole circuit? would two 1.5V penlites do, for example or do we need all 
>sorts
>of noise-free highquality adaptors?

Use +/- 12VDC as I said above. I don't recommend batteries.

>    and in what range should te control voltage be?

Control voltages are usually between +/- 5V for the EFM circuits
but could be up to +/- 10V
>
>we're also planning to build the VCA located on
>http://www.xavax.com/efm/cbook/vca3.html
>
>5) we bought a TL071 to use as the Op-Amp. is this right or should we use
>another model?

You mean for the pulse, sawtooth and sine... yes TL071 is OK
>
>6) do you by any chance know some sites listing all kinds of electrical
>components and their characteristics. For instance, which pin of transistor
>type XXXX is the base, and which one the emittor, etc.

If you find the manufacturer of the part... their web site will have
data sheets to show what pin is what. Try looking for ON semconductor,
Fairchild semiconductor, National Semiconductor for a beginning.

Good luck New-Beez!

H^)  harry
>
>Thanks a lot, Peter van Hamersveld and Egbert Teeselink.
>
>--
>Sent through GMX FreeMail - http://www.gmx.net
>

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