Hi, I'm planning on use a LM7809 voltage regulator to power my arduino project from a 12v engine battery, since I did a exahustive read, the internet recomends switching regulators as they are more efficient, so in the datasheet of the regulator they show a circuit to operate the LM7809 as switching regulator
So my question is about the diodes, can I use any zener and regular or have to be some especifics ones? and the 10 and 2k uF what kind of capacitors are?
Thanks in advance for your answers.
Why bother with 9V? Use the switching regulator and go right to 5V
Feed it into the 5V header pin, with a diode across the onboard 5V regulator (anode to 5V, cathode to Vin, so its npt reverse driven too much).
Or power the board via the USB connector.
Did you look at that circuit.
A lineair regulator converted to a switching regulator.
Looks like a sex change gone wrong.
Leo..
Buy a cigarette lighter DC/DC converter with USB socket.
That converts your car voltage to 5volt.
Use the USB cable that came with the Arduino, and plug that into the USB socket.
Google "USB Cigarette Lighter"
Leo..
CrossRoads:
Feed it into the 5V header pin, with a diode across the onboard 5V regulator (anode to 5V, cathode to Vin, so its npt reverse driven too much).
Why do you need that? Wasn't the Vin pin designed for this exact purpose from the start?
A switching regulator circuit without protection from overcurrent/inductor saturation? Sounds like an expensive
mistake to me.
So the datasheet is wrong about the switching circuit?
Why mis-use a lineair regulator as a (low frequency) switching regulator.
The 1mH/3A toroid and 2000uF cap alone will be 10x the price of a real switching regulator from ebay.
Leo..
a product of Fairchild and National Semi engineers tasked with 'come up with some ideas to Sell this new circuit'.
It works, most of the time.
Makes a better radio jammer than a power supply.
But, also great for killing batteries...