Some imagery...
Moderator: enderzero
-
N3ur0n0saurusl2exs0r!!!
- Hitching Post
- Posts: 913
- Joined: Thu May 06, 2004 10:47 pm
- Location: hidden
-
N3ur0n0saurusl2exs0r!!!
- Hitching Post
- Posts: 913
- Joined: Thu May 06, 2004 10:47 pm
- Location: hidden
Exponential converter. It takes the incoming control voltage, and turns it into an exponential curve for doing 1V per octave scaling. This allows for a few octaves of proper notes in the case of this design. Using a different style of design you can get nearly 13 octaves in some cases, but it's kind of a trade-off for the type of sounds and FM response you're looking for.
That's a Tempco over a chip containing 2 matched NPNs and 2 matched PNPs. The Tempco heats the chip a little bit, so that you get less drift and scaling errors over time and range of temperature. This design uses an OTA (look up operational transconductance amplifier) and a PNP pair to do the conversion from linear to exponential.
The designs that can do more octaves of accurate scaling use an NPN pair, which generally yields better results. However, this is kind of a hybrid version of an old design. Since it uses a certain integrated OTA chip, it needed the PNP pair design. So you lose accuracy. But it was a decent way to get the features of this particular oscillator in a fairly easy design. A discrete OTA would consist of several transistors in various configurations.
That's a Tempco over a chip containing 2 matched NPNs and 2 matched PNPs. The Tempco heats the chip a little bit, so that you get less drift and scaling errors over time and range of temperature. This design uses an OTA (look up operational transconductance amplifier) and a PNP pair to do the conversion from linear to exponential.
The designs that can do more octaves of accurate scaling use an NPN pair, which generally yields better results. However, this is kind of a hybrid version of an old design. Since it uses a certain integrated OTA chip, it needed the PNP pair design. So you lose accuracy. But it was a decent way to get the features of this particular oscillator in a fairly easy design. A discrete OTA would consist of several transistors in various configurations.