Hey everyone, i was wondering how to stop an LFO in a circuit so i can manually move the sweep of a modulation effect(i.e. the Electric Mistress)? is it simple?hard? what all do i need to know. thanks for any responses.
kris
You couldn't really stop it and manually alter the level. But you could disconnect it and control the sweep manually (eg; with a foot pedal).
Got the schematic?
You could basically stop it by putting a very very large value capacitor in series with it's timing capacitor, or even a series resistor with the timing resistor.... basically slowing it down so much that you don't notice it going. Schem?
-Colin
hey, there's an idea. Then you use an op amp to "mix" the "stopped" LFO and an external DC control level... there's some unpredictability to that setup though. but a good idea is a good idea!
I've done it, sans the external control, before as a mod.
-Colin
Quote from: kristoipher612Hey everyone, i was wondering how to stop an LFO in a circuit so i can manually move the sweep of a modulation effect(i.e. the Electric Mistress)? is it simple?hard? what all do i need to know. thanks for any responses.
kris
Most commercial flangers have this capability with a manual control that sets a
fixed voltage going to the VCO along with a Range control that mixes the LFO output and the fixed voltage. Take a look at the EH EM schematic to see how the range control is switched from using the LFO output to a fixed voltage at the opamp driving the VCO, simple but effective.
Any effect that uses a VCO can be can be converted to a manual sweep by using a varible voltage in place of the LFO output voltage.
Stopping an LFO is not hard. I did that for an effect in the Vibra-Matic mod to the EAN Tremolo. See
Quotehttp://geofex.com/FX_images/vibmatic.pdf
From March 2001.
However, as the others note, just stopping an LFO isn't what you're talking about.