I am building my first board and I want to build in AC powered DC supply to the board. I only need to power an AtMega from Arduino Uno, 1 LED, LM35, a 16x2 LCD with backlight, and drive the gate on a SSR. There are so many schematics and such for power supplies out there I am overwhelmed. I want to use the switching one to avoid giant expensive transformer. Seems no one does that anymore. I am told there are IC's out there that make switching power supplies very easy now but I have no idea which one. Could someone point me in the right direction?
I use USB phone chargers for a lot of my projects. They output 5V at 500-600 mA. They are pretty compact, too. I get them at the local thrift store for one or two dollars apiece. Look for the ones with mini USB connector.
Given the fact that you have not provided any details about power consumption I respectfully suggest that trying to build your own power supply is a bad idea.
I don't know the actual power consumption yet because I haven't run the numbers but the breadboard runs the whole thing off Arduino's +5 so it cannot be too much. I don;t want to use some over the counter thing because I plan to use this LM35 to control 120VAC and I don;t want to have to add in a wall plug inside the project box just to convert incoming 120 to a +5 VDC. That would make the project box huge. I just need to build what ever is inside one of those small wall warts onto the PCA. I am familiar with Linear power supplies but not the newer, smaller, switching ones. Don't want a giant transformer when I don't need one
The easiest power supply for Arduino is from an old computer tower it has its own box fan and output wires for +- 5volt, +-12volt and 3.3 volt and includes short circuit protection and a nice 110 volt plug with a minimal rewire on/off switch and LED indicator.
An SMPS is no trivial thing to design from scratch. I would strongly discourage attempting it. An "offline switching power supply" is more doable, but you are limited to only a couple watts in output at best which could be sufficient for a low power arduino project. The best alternative is to use a usb wall charger. Crack it open, pull the guts out and incorporate it unto your project. Ebay also has 1, 2, or 3 amp smps in the $3-$10 range.
jarrod0987:
I don;t want to use some over the counter thing because I plan to use this LM35 to control 120VAC and I don;t want to have to add in a wall plug inside the project box just to convert incoming 120 to a +5 VDC.
I,ve stripped and re-used several USB and phone chargers. The PCBs are usually tiny compared to the casing. You obviously still need to connect the mains wiring in a safe manner and isolate the mains circuit so that you don't get shorts between the mains and 5V sections, but that you have to do anyway if you build your own power supply.
