Exact half speed pot in Tremulus lune + ramp function

[RonaldB]

Hello,

I'm planning to build the tremulus lune with these two features in there.

I want to have a switch that:
1. Gives me exact half speed/rate
2. Activates a ramp up/down function so i can dail in the time on how fast it goes to half speed and full speed.

I have read the article on Geofex about this ramp feature in a Phase90 and Univibe. But can this be applied to the tremulus lune?
And how can i get the exact half speed, i read somewhere that Mike Fuller does this in his supa trem with a stereo pot wired in parallel.
But how can i do that?

Thanks in advance.

Ronald

[SonicVI]

The speed range is controlled by the 100uF polarized cap. If you switch a 100uF in parallel with it you will half the value and double the rate. If you want exactly double/half you need to use caps that are both exactly the same value. So either measure many to match a pair or use the lowest tolerance caps you can find. 

Can't help with the ramp function.