I'm currently using 2 100uF capacitors and an LM7805 to get 5V from my arduino from the 7.5V DC power supply I'm using, and this alo works with batteries up to 9v but it gets pretty warm.
I'm also wanting to get 3.3v for a breakout board I want to connect.
What's the most power efficient way to do this, that's pretty inexpensive (under £10($15 ish)), I know the 7805 is pretty wasteful (and I want to eventually change the power source to batteries).
I'm currently using 2 100uF capacitors and an LM7805 to get 5V from my arduino from the 7.5V DC power supply I'm using, and this alo works with batteries up to 9v but it gets pretty warm.
You say you are getting power FROM the Arduino. Did you mean FOR the Arduino?
Which Arduino do you have? Most will handle 7.5 volts in, directly, without you having to do anything. Most also have a 3.3V power source built in, to supply small amounts of current. What breakout board are you wanting to connect? How much current does it draw?
Apologies. I'm powering a breadboard with an atmega328pu and some other bits basically moving a project from my unofficial onto a breadboard. Then I'll move it to a permanent circuit board. I'm needing a regulator(s) that can efficiently provide 5 and 3.3 volts so that it can run on batteries and DC mains adapter. The UNO certainly is a lot more efficient than my one with a 7805.
The complete UNO schematic is available:
Scroll down to the Schematic and Reference Design section.
You should be able to replicate, on your breadboard, the 5V and 3.3V regulator design that the UNO uses.
When I created a 5V regulated supply using the 7805, it did not get warm. What are you powering from the 7805 besides the Arduino chip?
it gets pretty warm
Linear voltage regulators effectively 'burn-off' the excess voltage, so yes, they do get warm or even quite hot. Hence they are in a package that you can bolt a heatsink to.
There's the ATMEGA328 some LEDs a backlit LCD, and a RF link device and some buttons all using the 5v supply.
I want to add a WIZ810MJ or similar and that requires 3.3V.
I was hoping there'd be a simple drop in replacement for a 7805 that may cost a little more, but be much more efficient.
I also wanted the same for 3.3V.
Something like this may work for the 5V http://uk.farnell.com/jsp/displayProduct.jsp?sku=1696320&CMP=KNC-GUK-FUK-GEN-SKU-EMC&s_kwcid=TC|13123|TSR%201-2450||S|b|8220787509
but what about 3.3V, also what's the LM7805 3.3V version called?
I just ordered one of these http://search.digikey.com/scripts/DkSearch/dksus.dll?WT.z_header=search_go&lang=en&site=us&keywords=811-2196-5-ND&x=0&y=0 it's a drop in replacement for a 7805, but it's a switching power supply. Pretty cheap too, haven't received it yet though to tell you how it performs.