I am trying to make a power wheel car remote controlled.
My setup is: I am using a 4 channel relay module to control the car's motor in forward reverse motion and the relay is getting the signal from a RC receiver. I have a 12V lead battery. The relay board and the receiver board needs 5v power so i used a 7805 IC for 12v-5v conversion but the 555dc motors are directly connected to the battery. So basically all the components are connected to same source.
Problem:
Every thing works fine if I don't connect the motors. all the relays turn on and off with the remote accordingly. And the output wires for the motors are also changing the polarity accordingly
But when i connect the motors and turn the relay on using the remote it turns on and off very fast, maybe 15-20 times a second or more.
At first i thought maybe the motors are drawing too much current or causing a voltage drop which is causing the relay module to shutdown. so just to check I used only one 5v dc toy car motor but still the same thing happens.
Also I used a laptop 19v charger instead of the battery for more voltage or current and it's same.
I haven't tried using capacitors for the regulator output as i don't have enough idea which one to use.
However when i use a separate 5v battery source for the relay and receiver then it works properly with both the laptop charger and 12v battery. so something is wrong with my main power source when i use only one source. How can i use the 12v battery for everything.
I have attached the diagram also.. plz i need help. Thanks for reading.
Where is the Arduino?
Find what is leaving the RC Receiver.
Replace motors with LEDs and resistors. (is motor turning off feeding power back through ground?)
What relay module are you using?
I haven't used any arduino here.. And by "Find what is leaving the RC Receiver" what did you mean. plz explain
I dont know. it does not have any model number. just 4 5v relays on a board
Whatever is leaving the RC Receiver is entering IN1 ... IN4, which command the relays.
The colored wires in the diagram are going in the relays. when a key is pressed on the remote one wire gives around 3v output to the IN pins
Can you "scope" the noise on each IN1...IN4?
No I dont have any instruments for that.
Can you use four analog pins on an Arduino to "read" (the 3vdc) on IN1...IN4 values?
Please post a photo of the relay board.
What sort of R/C receiver and transmitter are you using?
my arduino is dead 
however what will it do if i could.
Looking for noisy IN1...IN4, but maybe that is what IN1...IN4 are supposed to do (maybe they are sending a coded pulse).
I thought the issue was with using same power source for all the components as when i power the relay and receiver separately it works fine.. and i am also not sure about this noise part.
The 12vdc source seems to be effected by the presence of the motors. I am also curious what is entering the IN1...IN4.
One more thing... once i tried connecting only the relay with separate source leaving the receiver as it is connected through the 7805. and same problem happened again. this means the receiver is turning off when the motor is connected which is causing the relay to turn off.
The 7805 is probably shutting down (making the receiver turn off). Do your motors have diodes and capacitors across the +/- terminals?
no. it does not have diodes or capacitors. how can the 7805 shut down.. i dont think the battery voltage drops below 7v which is the minimum volt for the7805. also i used the 19v adapter so definitely it does not drops to 7v.
Ok next time i will use a buck converter to convert 19v-5v. and then i will connect everything using this buck converter without the 7805. and i will use the small 5v motor(the motor also runs at 1.5v).
Insufficient potential.