servo controller circuit adjustment

[porchechop]

I understand that the circuit posted on the site www.555-timer-circuits.com of the servo controller (under servo tester) works as follows: u turn the potmeter and the servo turns by a degree proportional to degree the potmeter is turned.

Now i wantted to create an adjustment for this circuit.
first of all i want to create this with a joystick instead of a potmeter. But the joystick should also have to be pulled in reverse, meaning that i basicly want to control the amount the servo turns with a joystick, in both ways.

However, i am not sure if the initial circuit makes sure the servo turns back to the original state, but in what i have in mind it should do this.

Any help is appreciated

im kind of a noob in this :s

thx in advance
porchechop out

 

[duffy]

With that circuit, you turn the pot and the servo turns, you turn it back and the servo turns back.

Might want to check the range on your joystick, some of those only give a few degrees of output and that 56K may need to be a different value.

 

[porchechop]

the joystick still needs to be purchased, so i can basicly still choose the range on it.
And what would happen if the 56K changes value?

Otherwise that circuit does exactly what i would want it to to, except change the pot with a joystick

Thx for your help, much appreciated!

 

[Reloadron]

With circuit you posted and the pot fully CW the servo will be full in one direction and with the pot fully CCW the servo will be full in the opposite direction. When the pot is centered the servo would be centered. The Pulse Width runs from about 1.0 to 2.0 mS with a 1.5 mS center which should be servo center. So if you remove and replace the 100K pot with a 100K joystick it should do exactly what you want and expect. The PRT of the circuit is about 20 Hz.

Ron

 

[duffy]

^ If the joystick pot gave you the full range, but unfortunately most of them only move 45° or so out of the 270° range.

 

[Reloadron]

^ True and the greater the deflection angle in many cases the greater the cost. I was thinking of units like these. Those only offer 55 degree (+/- 27.5) deflection. Stock is a 5K pot with 10K available so the circuit would need modified.

 

[porchechop]

i only need the servo to turn about 30° both ways. so that is no problem

Thx for the help guys!