Arduino SIM808 GPS tracker - Power supply selection


i have made one GPS tracker using arduino and sim808 ,it’s working file with 5v and 1amp supply,but when i have connect this device direct to car battery through 12v to 5v converter voltage regulator 7805 so when we pressing horn so fluctuation is going and device getting restart. so what i have to do for making power supply and which capacitor i need to use across input and output of 7805 voltage regulator ,by which it will not resetting and 3-4 sec power backup will generate.

Thank you…

Hi Kiran,
You should use switching regulators like MP1584, LM2596 or LM2576 which can deliver the needed current to the device. You get readymade breakout boards of MP1584.
7805 is not suitable for driving GSM modules. Its current is limited and there is lot of power wasted as it is a linear regulator.

In addition you can use 1000uF capacitors for keeping the VBATT lines of SIM808 stable at the time of fluctuations.