servo signal to 0-5k ohm signal

[Bob K]

Might anyone know how I can convert a throttle
channel signal ( std servo signal) to a 0-5k ohm signal?

I have a speed controller that only takes 0-5k ohms
from a potentiometer and I would rather not use a
servo-linkage-pot type of set up.

Thanks!

Bob K

[xtal]

you might be able to use an rc network [to integrate the channel pulse] and directly
connect to the gate of a jfet .. and use the jfet as a variable resistor......

you may be able to do the same with an make shift optical coupler[led and photo resistor]....

[jeffs555]

There are examples with source code for decoding a servo signal with a PIC or AVR, just search for them. Once you have the servo signal decoded, you can drive a digital pot to get your 0-5k resistance. Digital pots come in many flavors with different serial interfaces. Get one to match the serial hardware in the PIC or AVR. Here is one with an SPI interface. http://www.analog.com/UploadedFiles/Data_Sheets/639855AD5160_0.pdf

[slipstick]

Look for ccts for Joystick interfaces for simulators for some ideas. That's how many of them work, though obviously they also decode the channels from a PPM stream rather than just taking one servo output.
E.g.
http://www.welwyn.demon.co.uk/joystick/joystick.htm
http://www.rcdesign.ru/eng/electronics/rc2joy

Steve

[jbeanelliott]

The website below sells an "RCA Analog Interface" for $48.00

http://www.robotmarketplace.com/marketplace_elect_other.html

Use this board to interface between your RC receiver and large speed controls that are not already set up for radio-controlled operation.

* The board closes a forward and reverse circuit
* The board provides a 0-5K variable resistance
* Ships with a Futaba J Cable installed

[Bob K]

Thank you , gentlemen!

Bob K