Ramping Speed Control?

[Paul Marossy]

Is there an analog way to take the speed control of something like the EA Tremolo and use a switch to double the maximum speed, but have it ramp up from the slower maximum speed to the higher maximum speed over a certain time interval? I'm thinking something like maybe 2-3 seconds.

[Mark Hammer]

The Geofex LERA comes to mind.  Particularly since the EA speed control is a variable resistance, rather than a voltage divider.

[Paul Marossy]

The Geofex LERA comes to mind.  Particularly since the EA speed control is a variable resistance, rather than a voltage divider.

Haven't heard of this one before! Not sure if this would work or not. Sounds like it just varies the speed to emulate a motor that isn't completely stable.

I want the switch to make it go from one speed to the other and stay there until you want it to be slower again. So the two speeds would flip-flop.

[midwayfair]

Check out the Multiplex's charge circuit for changing the delay time with an H11F1:
http://1776effects.com/wp-content/uploads/2012/11/Multiplex-Build-Doc-1.7.pdf

Schematic's on page 11, and it's the little block of stuff to the left of the photocoupler.

If you use a latching switch, it'll "top out" at a maximum or bottom out at a minimum. There are resistors that control how fast the change happens.

A more extreme example of this is in Culture Jam's Neptune. That one works much more quickly.

[Mark Hammer]

I have a Pearl PH-44 phaser that includes analog ramp-up/ramp-down.  I think I may have a schematic for it somewhere, but I'm not absolutely sure.

[Paul Marossy]

Check out the Multiplex's charge circuit for changing the delay time with an H11F1:
http://1776effects.com/wp-content/uploads/2012/11/Multiplex-Build-Doc-1.7.pdf

Schematic's on page 11, and it's the little block of stuff to the left of the photocoupler.

If you use a latching switch, it'll "top out" at a maximum or bottom out at a minimum. There are resistors that control how fast the change happens.

Aha! I think this may be more along the lines of what I'm thinking. But would it work for changing the speed of an LFO? I see it's connected to the VCO pin of the PT2399, so I would assume so... but I am not an expert in this area.

I have a Pearl PH-44 phaser that includes analog ramp-up/ramp-down.  I think I may have a schematic for it somewhere, but I'm not absolutely sure.

Send it my way if you find it. 

[Mark Hammer]

Check yer website e-mail.

[samhay]

As usual, R.G. thought of this a good while ago: http://www.geofex.com/FX_images/ramp-lfo.pdf

[Paul Marossy]

Check yer website e-mail.

Thanks Mark!

As usual, R.G. thought of this a good while ago: http://www.geofex.com/FX_images/ramp-lfo.pdf

Is there anything R.G. hasn't thought of? 

[midwayfair]

But would it work for changing the speed of an LFO

Yes -- depending.

You need to use an LFO whose rate pot is a variable resistor, and not a voltage divider. This is most of them. You simply hook up the H11F1 across the pot, in series with a second rate pot. There are a couple issues to handle: Your second rate pot will divide in parallel with the first. If you want to be able to slide up to a setting that is less than twice as fast, you'll need to use a second pole on the toggle to switch in a resistor of size equal to the pot, and double the size of the rate pot. Flipped one way, it's a constant pot of 1/2 size. Flipped the other, it's a variable pot of half size.

Note that this is untested. I gave similar suggestions to someone else on BYOC once and he didn't get it to ramp (at least not slowly enough), but I described it using the Neptune's and not the Multiplex's (which I think didn't exist at the time). I just have't been able to test it. But there's no reason it shouldn't work: It's just a timed circuit turns on a parallel resistor in a set amount of time.

As usual, R.G. thought of this a good while ago: http://www.geofex.com/FX_images/ramp-lfo.pdf

So much better and cheaper.

[armdnrdy]

Look at how it's done in the Roland Jet Phaser.

I got a little ahead of myself.

Midwayfair seems to be on the right track.

As far as ramping....you might try (breadboard) to incorporate some type of time constant configuration.

Here's a link to a TC calculator.
http://ladyada.net/library/rccalc.html

[R.G.]

The Geofex LERA comes to mind.  Particularly since the EA speed control is a variable resistance, rather than a voltage divider.

Haven't heard of this one before! Not sure if this would work or not. Sounds like it just varies the speed to emulate a motor that isn't completely stable.

I want the switch to make it go from one speed to the other and stay there until you want it to be slower again. So the two speeds would flip-flop.

That's LERA. It ramps from one to the other, switch controlled. It's basically what you want if you can adapt your LFO to run from an LDR.

[jmasciswannabe]

Danelectro Rocky Road has a ramping feature as well as the old school maestro big box phaser. Schems are out there...