I am trying to run the spark Core off a 9v PP3 battery. I have put a 7805 voltage reg in circuit with the 9v and works grate for about an hour then battery seams to be running low. The 5v is going in on the VIN pin of the core. From looking a the current draw on the 5v side i am getting about 1.32A is this correct, i had thought that the spark core only pulled about 500mA. i am getting the same results on a 5v PSU on the same pin.
@leeeng, the Core should only pull about 150-350ma with the WiFi enabled and active. The Core’s onboard regulator can only handle 500ma. The 1.32A is either being incorrectly measured or something else connected to the power bus is drawing current. Is your Core very hot? How are you measuring the current? Do you have anthing else being powered besides the Core?
I agree with peekay there is an issue with too much current, and also I would recommend an LDO regulator over the 7805 which has a high dropout voltage. If you don’t need a 5V rail you can also regulate down to 3.3V and attach the output of the LDO directly to the 3V3 pin. Because it’s an LDO, it has a lower dropout voltage than the 7805 which is the voltage dropped across the regulator before it will regulate to 3.3V. In this case here’s one that has about a 1V drop out voltage: http://www.digikey.com/product-detail/en/LD1117V33/497-1491-5-ND/586012
You shouldn’t need to heat sink it either, but should probably add a good 22uF to it’s output (or more if you wish).
Unplug your battery power, before you plug in your USB if you hook something like this directly to the 3V3 pin on the Spark Core.