making a pulse clock for analog bit crusher

[loss1234]

recently i have been messing with sample and holds and colin's bit crusher.
i really just want to make a new clock that is voltage controlled.
but every time i try to open and shut the JFET with anything other than colin's clock, it doesnt work.

supposedly this CV 40106 puts out a pulse wave that works for sample and hold's but i tried it and got nothing.

http://electro-music.com/forum/phpbb-files/40106vco_954.png

SO i have a few questions
1. does anyone know what kind of wave works best for turning a JFET on and off? thin pulse? negative or positive?
2.. is there an easy way to convert a regular square into a pulse?

if i can figure this out, i really can then use the JEFT in all kinds of applications.

thanks so much!!!

[frequencycentral]

HI Dan,

I think I've referred you to this before: http://fa.utfs.org/diy/roland100m/schematicsshow18.html

The Analog Bit Crusher is just a sample and hold really, have a look at how the Roland S/H shapes any input waveform to be suitable for the FET in the above schematic. It's worth breadboarding and analysing whats happening at each stage with a DMM and a 'scope to get your head around it.

[loss1234]

i tried to get the general idea but it is quite blurry.
just so people know, one thing i got to work was using a 40106 as a clock and powering it from gnd/-v.

(pin 14...gnd
pin 7...-v)


that worked. (but you need dual supply)

[rackham]

For something that runs off +9v try one of these?

http://www.queencircuit.com/Generators/Triangle_and_Squarewave_Generator_by_1458.asp

And perhaps have a look at the first circuit in here:

www.national.com/an/AN/AN-32.pdf

Hope they might help?

[loss1234]

thanks but it isnt the LFO i am having trouble with anymore

it's the darn JFET. it only works when it goes from negative to positive.

i am going to try a mosfet