Neutron with LFO!

[Gila_Crisis]

hi,
I'm thinking about building a Neutron and I wanna had an LFO to modulate the filter.
for the LFO I'm thinking about the one from the Tremulus Lunes (which I find a good starting point).
But know how can I implement the lfo in the circuit?
My idea was to use a LED/LDR and connect them on the LDR-side of the photocells of the neutron.
or from the out of the LFO should I control the LED-side of the photocell?

what do you think about?

[MarcoMike]

hey, this sounds like a good plan...

but as the Neutron has dual power supply I would go for something like the LFO you find here:

http://www.schematicheaven.com/effects/telray_phaser_vol_pfa_pfv.pdf

the ability to change starting and final point (or centre and amplitude in this case) of your modulation is definetly a plus!

[Gila_Crisis]

up

[MarcoMike]

the photocell in a mutron is voltage controlled: the envelope of your signal is translated to a intensity dependent voltage signal, which determine the brightness of the led part of the optocoupler, so the resistence of the 2 resistive parts, controlling the sweep in frequency of the filter.
any other way of applying a voltage to that LED part can be used to control the filter frequency, so you just need to drive the led with a voltage (which can be the output of your lfo)
just try not to "burn" the optocoupler exceding its maximum voltage.

[Gila_Crisis]

that's about the idea I had, driving the led with both the envolope circuit of the mutron and the LFO at the same time