glide/portamento/slew/lag whatever

I think I like the name portamento best, it makes it sound fancy. But whatever you call it, when you play different notes on the keyboard and it slides between the notes.

I gave my friend my kraftzwerg last month, which doesn't have a portmento, and while he likes it he is really missing that glide. Because that is what an analog synth is all about, slidey sounds. 90% of all synth patches I make have at least a bit of glide. I decided I would make him a glide circuit in a tiny little tupperware container., using parts I already had laying around. 

So, I used this extremely simple circuit by Harry Bissell:

I didn't add input or output resistors because he won't be driving multiple things, and I wanted to keep the control voltage intact without voltage drop or that 1k output resistor causing problems. I don't think it will matter and tl072s are very cheap. I used a tl072 instead of the LM1458 in the circuit because thats what I had.

I didn't have any of the correct capacitor sizes. So I used a 15uf electrolytic and put a 100k potentiometer in series with the 1M, so he has more control. Otherwise, it was difficult to dial in the desired glide time on the 1M pot.

I ran it off of two 9v batteries

So here it is

UPDATE in April, I don't think it worked which is sad. Good thing it was cheap and easy