Hi,
i have an Intel Galileo board compatible with Arduino Uno. I am about to make a Bluetooth controlled robot vehicle and i also have servo requirements in the project. I am confused about providing correct supply to every components and motors in the project.
Below you can find my circuit as attachment (just a model circuit with no ground connections). I was thinking about buying a 12V 7.2A/h lead acid battery. I am afraid that it may damage some low power modules.
Is my circuit below a correct one?
Will it supply the required current to every motors and modules?
Will there be any problem if the motors stall..?
I don't know much about electronics... Can anybody help me..?
You need capacitors on the input and output of each regulator. Both 0.1 uF ceramics and bigger ones like 100uF.
Then you might need more current than 1A for the servos, motors and the processor. Is the bluetooth module 5V.
Yes if the motors stall the regulators will over heat.
For dc motors, i have directly connected to the battery. Hence i think there wont be a problem for dc motor supply even if stalls. But my concern is with servo motors. I don't exactly know whether the 7805 will be able to provide all the energy for a servo.
For heating of regulators, will it provide any serious problems later even if i add a heat sink..?
Any working circuit with such high power batteries will be helpful to me.....
If you're concerned about heat sinking, Recom Power makes some neat little switching replacements for 3-terminal regulators.
Mike points out that "stalled servos" will overheat your regulators, which is true. To monitor this, if you add a 0.1-ohm series resistor to the GROUND terminal of each Servo, you can monitor it with an A/D pin and fault if stalled. If the voltage across the resistor goes above 100mV, you simply FAULT or REVERSE, however you want to treat that event. A similar method could be used with the other 4 motors, since if you stall those, you will eventually make smoke with the L293 Controllers. Have you looked at the inexpensive modules with the L298 on them? Those also have an on-board 5V regulator you might want to take advantage of. There are jumpers on that board you remove to allow you to wire over to your resistors to measure current.
You can get nice cheap buck regulator boards on eBay based on LM2596, some
even with voltage readouts. You adjust a pot for the output voltage and they
handle perhaps 1.5A IIRC
I agree with the other posters that you would be better off with a buck regulator for the input voltage for your bank of 5V regulators and you can use the 12V for the motor voltage ONLY. It is never a good idea to use 12V as the input voltage for the LM7805 because you will guarantee that it will always run hot because it has to disipate about 5 or 6 volts . The 5V regulator has about a 2V overhead but anything above and beyond that has to be disipated. The ideal input voltage for the 5V regulators is 7V, so that's what you should set the buck regulator for. You might want to consider getting a 5V 5A power supply.
Thanks for the reply...
Lead acid proves to be bigger size for my project. So how about i change to 7.4v li po batteries in place of 12v lead acid. I am aware that dc motors run a litle slow with 7.4v.. but still the circuit is ok with 7805's and 7.4v lipo(better dhan 12v lead acid).. right...?
