How do you mean control the servos without a radio? I think that's the only way to get a signal to them... right? I know there is a failsafe of some sort for nitro powered cars in the highend radios so the car will stop instead of using the last command it had before it lost contact. Not sure how that works though... prolly part of the receiver.
Now that I think about it I think I understand what you mean. You must be making something that you need to control with the servo onboard so you don't need a radio? Like a wire between the servo and something to control it that way?
Servos have 3 wires - one for power and the other 2 are used to control each direction the servo is capable of going. Maybe you could use some sort of dial? to control the servo through it's sweep? or unless you just need the servo to operate from full lock to lock? then maybe some kind of switch? Not sure what kind of switch or dial would work though.
well you guys are kind of right and kind of wrong. Yes a servo has three wires. one hot, one ground and one signal. the signal works on a pulse thing. I found a thing caller aq servo driver which is basically the control with out the radio frequency stuff.
Posts: 112 From: St. Bonifacius, MN USA Registered: Mar 2000
3 wire servos work as follows: 1 wire +v, one wire ground, the third wire signal. The signal can be either positive shift (most radios) or negative shift (airtronics I think). The pulse width if the signal will be 1.5 ms for the nuetral position and 1 ms will be full deflection one direction and 2 ms will be full deflection the other direction. I've built servo drivers and related acc. and over the past 30 years of RC tinkering I've run across a lot of near gadgets.
Posts: 2740 From: Merritt Island, FL USA Registered: Jun 99
Another way to put that would be to say that on the signal input a pulse width modulated pulse train with a period of 1 ms and a 50% duty cycle is the neutral position, any duty cycle less than 50% is reverse, with 0% being full reverse, and any duty cycle more than 50% is forward, with 100% being full forward.
But thats six of one and half a dozen of the other.
------------------ Dillon - Titusville, FL Black '87 SE V6 "Matched Perfect and Staggered Special"
Jul 18th, 2000
Posts: 343 From: Huntsville, Alabama, USA Registered: Jul 99
I used to have a kalt barron 30 heli. Too many crashes - too much to fix. I now have a Midwest cardinal squire (.60), Monocoupe(.15), a Douglas A-26 (Twin .061), an electric park flier, a 1/8 car, a sail boat, and a electric mahogany runabout. I do this r/c stuff, work, have a daughter, have a Fiero, 2 Porsches, a Dakota quad cab, 4 cats, a house. NO WONDER I DON'T GET ANYTHING DONE - but I sure have fun!
I run R/C Cars. Its Cool, but it gets $$$. I run a new HPI NITRO (All the toys) With a Nitro Star Por 12SR SC engine. Guess what body is on it?? MUSTANG!!!! Ohh Yea! .If they ever make a Fiero body Ill scoop one up QUICK.... Yesterday I picked up a new HPI Proceed and a Pro 21R SC (2.3HP Zooooom)