Base band TZFM-VCO works!

[Rene Schmitz]

Hi all,

after giving up my concept for the discharge switch, I now have a 
new schematic, and best of all a working prototype. I attached the 
block diagramm to this message. The trick was to use a zero crossing 
detector at the FM input and introducing a second switch, which can
optionally 
invert the input for the a schmitt trigger. This does exactly the same thing 
like the proposed FF-discharge section, but since there is no FF it cannot
"crash". This is closer to the Electr*n*tes TZVCO now, but I could still
get away without rectifiing the FM input.

I've toyed arround with the prototype this evening, and I put up two mp3
files to my website. www.uni-bonn.de/~uzs159/samples/tzfm2.mp3 and tzfmvco.mp3
The first file was made at the weekend using the currently discussed
heterodyning method. I've recorded the second one this evening using the
TZ-VCO. (Playing octave jumps, sorry for my lack of musical creativity.) 
You can hear the straight sound from the left, and a VCF-processed version
on the right. Don't expect something fancy however, I set the arrangement
to a fixed waveform. The real fun maybe starts when one modulates the
amplitude of the program VCO, or modulates the expo input of the carrier
TZ-VCO. (And uses more than one program VCO)

I've noticed some dirt in the sound. I suspect that this is form the zero
detector (a comparitor). I'll make it a little bit hysteretic, and see if
that helps. There are other minor tweaks that I'll do, but as it is the
circuit works. I'll post a schematic up to my website as soon as I find the
time to draw one.

Bye
 René


error:asciiartisnotfully  \ uzs159 at uni-bonn.de
supportedwithyourcurrent   \ http://www.uni-bonn.de/~uzs159
displaydriversettings...    \ http://members.xoom.com/Rene_Schmitz