Some time ago I wanted an easy way to power logic circuits on breadboard (both 5V and 3.3v circuit as needed). The product 121305 3.3V / 5V Power Module for Breadboard – Deep Blue seemed to fit the needs pretty well at few dollars (around $3.5). It takes 6.5~12V DC input voltage and outputs regulated DC 3.3V / 5V. It fits nicely to a breadboard I have.
The board has normal 2.1 mm DC power connector for connecting the power input 6.5~12V DC. The board has power switch in it do I can easily turn the power on and off. The board has pins on the bottom that feed the power to the breadboard. The voltage sent to the breadboard is controlled with a jumper on the left (3.3V or 5V depending on setting).
On the right you can see pins where both 3.3V and 5V are available on separate pins if both voltages are needed on the same project. There is a LED that shows when power is on. Those are the features I liked. Well designed. The board has also USB female port that outputs 5V power to USB devices, which I have not yet needed. Here is a close-up of the electronics on the board.
The electronics on the board consist basically of reverse polarity protection diode, two regulator ICs, several filter capacitors, LED and current limiting resistor for it. Pretty basic well working linear regulator circuit without any special fancy features. The regulators ICs on on-board are AMS1117-3.3V and AMS1117-5V.
According to AMS1117 datasheet the AMS1117 series of adjustable and fixed voltage regulators are designed to provide up to 1A output current and to operate down to 1V input-to-output differential. It means that the board 5V regulator needs higher than 5V+1V=6V voltage to operate, and because there is diode on the power input (protection against wrong polarity), we need somewhat more for diode drops (so we need around 6.5V).
The regulator ICs are designed to provide up to 1A output current, but taking into consideration the small circuit board and so little heat sinking capability on the board, I don’t think those regulators can take 1A current for more than very short time especially if input voltage is considerably higher than 6.5V. I quess the safe current they can handle for longer ran would be up to several hundred mA.The AMS1117 regulator IC has an internal power and thermal limiting circuitry designed to protect the device under over load conditions, which is good so that if you overload the regulator it does not break down.
121305 3.3V / 5V Power Module for Breadboard – Deep Blue seems to be a well built circuit worth to consider if you need this kind of power supply. The price is reasonable, although there are also cheaper alternatives with quite similar specifications on paper.