StephenGiles
Well-known member
This is what I have now:
With a guitar connected to the preamp (not shown), when a note is played the signal at the base of the transistor turns it on, and its emitter goes high to the voltage set by the Filter Start Frequency pot. The voltage then decays at a rate set by the Sweep Time pot to a voltage set by the Filter Stop Frequency pot. This sweep generator is quite clever because if the Stop Frequency voltage is set higher than the Start Frequency Voltage you get a reverse sweep at the VCF. Sounds familiar? Well yes, Electroharmonix had this down to a fine art 25 years ago. Now I would like to make the Start Frequency voltage be a measure of the strength if the note played, but keep the sweep time as is. Problem - how does one transfer the Peak value of the input signal on to the + input of the Filter Start Frequency buffer IC without interacting with the Sweep time.
What I am ultimately after is a ripple free sweep, starting at a point controlled by the strength of note played. A normal envelope follower cannot provide ripple free operation from a guitar output.
Stephen
With a guitar connected to the preamp (not shown), when a note is played the signal at the base of the transistor turns it on, and its emitter goes high to the voltage set by the Filter Start Frequency pot. The voltage then decays at a rate set by the Sweep Time pot to a voltage set by the Filter Stop Frequency pot. This sweep generator is quite clever because if the Stop Frequency voltage is set higher than the Start Frequency Voltage you get a reverse sweep at the VCF. Sounds familiar? Well yes, Electroharmonix had this down to a fine art 25 years ago. Now I would like to make the Start Frequency voltage be a measure of the strength if the note played, but keep the sweep time as is. Problem - how does one transfer the Peak value of the input signal on to the + input of the Filter Start Frequency buffer IC without interacting with the Sweep time.
What I am ultimately after is a ripple free sweep, starting at a point controlled by the strength of note played. A normal envelope follower cannot provide ripple free operation from a guitar output.
Stephen