VCF

[Niklas Rönnberg]

Hello!
I'm still working with the VCF...
Here is the question:
In this circuit there are a 10K from the output (pin 8 on LM13600) to
-12 v. http://www.geocities.com/efm_gc/cbook/pics/vcf8b_sd.gif
Should I also have a resistor from the output of the TL072 to -v?
http://www.itn.liu.se/~nikro/littleman/vcf.gif
In the circuit with the LM13600 there is only a 10k pot for resonance,
in the other circuit there is a 2.2k resistor and the 10 pot... What
does the 2.2k resistor do? Do I have to use it?
I think both circuits come from Tom, so maybe he knows the answer?
Regards
/Niklas 
______________________________________________
|                                            |
| Niklas Rönnberg, Lecturer                  |
|                  - - -                     |
| Dept of Science and Technology (ITN)       |
| Linköping University, Campus Norrköping    |
|                  - - -                     |
| Phone: +46(0)11-363316 Fax:+46(0)11-363270 |
| E-mail: nikro at itn.liu.se                   |
| Homepage: http://www.itn.liu.se/~nikro/    |
|                  - - -                     |
|      "The semiotic $64,000 question:       |
|    Why and how is who communicating what   |
|       to whom and with what effect?"       |
|____________________________________________|