For all you Electrical wizz kids

[dumbass]

A while back I posted something that was sent to be. It was a YouTube link showing a simple modification to a 24v brushed motor setup. The bike happened to be an Ezip but that's not the point at this moment. The videos show the use of a 48v brushed controller on a 24v brushed motor. This person looks to be using an adjustable resistor on the hall wire to control (limit) the controllers output.

My question is...if I have a simular setup and wanted to try this what size resistor (pot) would I need to install? I have a standard 0-5v hall throttle.

Bob

http://www.youtube.com/watch?v=ehKSUmutGnM&feature=mfu_in_order&list=UL
http://www.youtube.com/watch?v=WjTyBVPyqlw&feature=mfu_in_order&list=UL

 

[heathyoung]

Basically what you are describing is a resistive divider that scales the output of the hall of the throttle.

One end of the pot goes to the hall output, the other to ground, and the wiper to the throttle input of your controller.

Since the output of the hall is being loaded to ground, you don't want to pull too much current - so assuming an absolute maximum of 50Ma current sinking ability, you probably want about 30ma to keep it safe.

R = V/I, V= 5, I = 0.03 (30mA) therefore 166 Ohms. In reality, this is not a readily available trimpot size, the the closest will be a 200 Ohm unit.

Since you probably don't want the full degree of scaling (ie. 0-100%), if you only wanted to adjust 50-100% you would put a fixed resistor in series with the negative to the trimpot (ie. use a 100 ohm trimpot, and 100 ohm resistor to get 50-100% adjustment).

 

[dumbass]

heathyoung, Great explaination, I almost understnad it. Just kidding (not really). So if I go to my local Radio Shack and buy a 200 ohm resistor pot or smaller and wire it between the return leg and the ground...Correct? I am saying 200 ohm because I'm guess I would want about 75% of the full capasity of the controller. Based on your calculation of 166 ohms for full throttle that would be about 125 ohms. Does this sound right?

Thanks again,

Bob