Instructables

help upgrading an old RC truck?

Ive got an old New Bright RC truck, i got it around 2000 so as you can assume the batteries arent very good anymore.
im not looking to repair the batteries though, im looking to upgrade the truck with a little bit of some newer technologies.

heres where i ask for help:
i dont want to overpower the control board in the car, since it may have adverse effects on how it performs, so i just want to up the power to the motor. i have some D2583 and B1658 transistors, i found a datasheet for the D2583's that says they are high power NPN transistors, but no such luck with the B1658's.
using the D2583's (i have 6 of them), i want to create a circuit that runs from the main board, and acts as a second H-Bridge (or some sort of control circuit) that controls more power, so i can safely run more voltage to the drive motor without overpowering the main circuit board.

does anybody know how i can do this?
i have attached a picture of the area on the circuit board where the original H-bridge is.

Picture of help upgrading an old RC truck?
rirdrifta2 years ago
Have you replaced the transistor that goes to the antenna with a higher power transistor to see if doing this will increase it's signal distance from the controller. If you do this please tell me because I would like to know if it works.
usbg3rd2 years ago
Here is the solution just four transistors could do it (obviously u might need resistors to control the current i did not know the specs of your rc truck that's why i didn't use any resistors)

now all you have to do is just disconnect the wires from the motor now when the left button is pressed one of the two wires goes at high potential and conversely when right is pressed the other goes at high potential (you can figure it out using voltmeter)

NOW connect the wire that goes high when left button is pressed to the left labeled in the schematics and similarly right to right wire (IF U WANT I CAN MAIL U THE SCHEMATICS)

this will almost isolate the motor and its current from the other circuitry
and here transistor is operating as a switch (in case if u don't know)
rc answer.png
usbg3rd usbg3rd2 years ago
i for got to mention that ground should be common too.

connect "MOTOR NEGATIVE WIRE" to left labeld in the schematics

connect "MOTOR positive WIRE" to right labeld in the schematics

connect " BATTERY NEGATIVE TERMININAL" to ground in the schematics

connect "a NEW BATTERY" to the source in the schematics
I had a RC truck made by New Bright which had a 7.2 volt battery (I think) and the battery was completely dead and I had no charger for it. So what I did was connect a 9 volt battery to it just so I could see if the truck worked. Now Im not saying that you should do the same and if you ruin your truck its not my fault, but there was no damage to my truck. And later I used a 12v battery and it still worked.
i did same to one of my rc car and i increased the battery from 6 to 9V after that it was not operating with 6V but only operated with 9V afterwards :) strange but true
MattJoeP2 years ago
Hi there, I think you could create a relay with the transistors from where the circut detects input from the controller so that when power is detected going to the motor the other end of the relay to allow more power directly from the battery.
maomao1232 years ago
I also want to help you, but I don't know how to do, I'm so sorry.
http://www.crusher.so
rrrmanion2 years ago
Just use the transistors to form a darlington pair, then hook that up to a relay. this should prevent draining power from the board excessively, and minimize back EMF
psymansays2 years ago
Do you want to build a new H-Bridge board that just uses the signals from the old board? Connect the ground on the old board to the ground on the new board, and run wires from the base pins of the four existing H-Bridge transistors (center pins) to the bases on the new circuit's transistors. Only connect the higher voltage to the new board. The H-bridge circuit should be a standard design, from there. Move the motor's wires from the old board to the new one, and remove the old board's h-bridge transistors from the existing circuit.
didnt u make a robot from ur rc truck rather than again making a truck? if u r interested then i ll tell u.. :) :)
zack247 (author)  Pranjal Joshi2 years ago
eh..
robots arent as fun as controlling it yourself :3
jbaker222 years ago
I made this instructable http://www.instructables.com/id/how-to-supercharge-a-cheap-radio-control/
frollard2 years ago
Unless you're changing the input voltage to something the existing transistors can't handle, or upgrading the motor to something that requires more amps, why change? Can the A928A not handle any additional current? Add a bigger heatsink :D
zack247 (author)  frollard2 years ago
these transistors are like the standard 2n222's but a bit taller, adding a heatsink to them would be quite difficult without breaking or damaging them (at least for me)
i just wanted to play it safe because im moving from 6v to either 9.6v or 19.2v, im not sure if the standard transistors could handle all that, or the control chip.
The whole thing probably has a regulator for the control chip...as for the transistors, look up their datasheet to see what the max voltage/current is - I bet it's got some headroom to play with.

Worst case if you can't add a heatsink is to add a fan :D
zack247 (author)  frollard2 years ago
nope, no regulator, just a diode and a resistor.
adding a fan or heatsink cant really be done with the transistors on the board, the board is mounted upside down and its mounted using the battery contacts.

thats why i figured another transistor set would be the best idea, i could use a regulator for the board and straight power for the drive motor.
Wouldn't be too hard to add a regulator just for the control chip - did you look up the tolerances for the existing transistors?
zack247 (author)  frollard2 years ago
not quite yet, ive been a little sidetracked but i will soon
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