[sdiy] Radio Controlled Synth ?

[Scott]

I can't tell you about the ms it takes, but the servo can travel it's
entire range in just under a second.  The range isn't quite as large as
the turn of a pot.  The servo's do have a lot of torque, and something
could be rigged up with gears to turn to pot, Im sure.

Servo's are pretty quick.  When you've got $1000 zipping around at
100mph through the air, sometimes directly towards the ground, you want
those things to be responsive!
Actually, the main reason I don't fly anymore is because it made me a
nervous wreck!

-----Original Message-----
From: synth-diy-bounces at dropmix.xs4all.nl
[mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of Needham, Alan
Sent: Monday, July 09, 2007 8:58 AM
To: synth-diy at dropmix.xs4all.nl
Subject: RE: [sdiy] Radio Controlled Synth ?

OK, it's not the quickest responding system on the planet ---
BUT
how fast would you wiggle a joystick ?
how fast is a typical, cheap RC servo ?
so if it is as crude as nailing a servo onto a pot shaft
assuming the pulse rate is about 20ms then a microcontroller
could be as quick as one pulse to update to a new value, 2
pulses should be plenty. That would be fast enough for most
joystick applications, pitch bend, filter mod, etc.
It might be fast enough for an RC theremin pitch control :-|
	Alan - now mentally wibbling joysticks


-----Original Message-----
From: Tom Wiltshire [mailto:tom at electricdruid.net]
Sent: 09 July 2007 11:25 AM
To: Needham, Alan
Cc: Scott; synth-diy at dropmix.xs4all.nl
Subject: Re: [sdiy] Radio Controlled Synth ?



On 9 Jul 2007, at 09:58, Needham, Alan wrote:

> Now there's an idea ...
> the signal to an RC servo is a series of 5v pulses, pulse width
> modulated for position, it souldn't be too hard to average this
> to get a crude voltage control signal, a useful signal shouldn't
> be impossible.
> 	Alan - lost the plot again!

Yes, I've played with these too. It'd be easy to filter the pulses to  
get a CV output, much like the PWM output on my own EG or LFO  
project. The problem is that the PWM output for RC is at a much lower  
frequency (can't remember of the top of my head, but might be as low  
as 50Hz) so you're going to need a filter with a very low cutoff to  
remove any ripple.

T.



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