[sdiy] Voltage references in VCO

[Paul Schreiber]

a) you need at least 2 volts more on the input side than the output side for these types of regulators to work.

b) you are trying to get cleaner *power* to the VCO. This is not what the post is about. Rather, in a VCO design, there will be a *reference voltage* (usually +5V) that either the integration cap is tied to, or that the exponential current pair is referenced to. There are many stable +5V reference chips to choose from, based on price/performance.

Paul S.

  ----- Original Message ----- 
  From: Benjamín Velasco 
  To: Synth DIY List 
  Sent: Monday, April 10, 2006 12:00 PM
  Subject: [sdiy] Voltage references in VCO


  Hi list!!
   A few days ago i started a topic about my LFOs affecting the frequency of my VCOs. Searching the archives i discovered this a very common problem. Someone here suggested to use on board voltage references in the VCO rather than using massive decouple in all the other modules. This makes sense to me because in my synth the only modules that need critically good supply voltages are the VCOs. So i plan to use lm317/337 in each of my VCOs. My question is if it is better to connect only the critical points of the VCOs to the on board refences, or it is enough to use them for the whole module? I use +-15V. Can i use the lm317/337 to get a cleaner +-15V from the dirty +-15V or do I need higher voltage at the inputs of the regulators?? 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://synth-diy.org/pipermail/synth-diy/attachments/20060410/b48c029c/attachment.htm>