Powering components on a breadboard is always challenging. Solderless breadboard certainly make it easy but for elegance, you will need to invest in an expensive bench power supply. Trying to power a mass of sensors using the power-pins on a Raspberry Pi or Arduino board is not a good idea because of the limitations placed on maximum current draw that these boards apply.
A $1 Breadboard Power Supply module from China is an elegant drop-in solution. It supports 6.5V – 12V input and outputs stable 3.3 V and 5V over two rails up-to 700mA. You can also configure it to supply 3.3V on both rails, 5V on both rails. By using a 3.3V to 5V Logic Level converter, you can freely power and mix up sensors that use 3.3V and 5V.
I used a relatively ordinary transformer based 1.5V – 12V 500mA variable power-supply that is used around the home to power electronic toys etc. and measured the voltage that was being output by the Power Supply Module.
|Adapter Label||Transformer Actual Output||Module 3.3V Output||Module 5V Output|
Looking at the table, the following important points maybe noticed:
- The board requires approx. 6.5V to trigger the stable output voltages. This means that you cannot power it off a Mobile Phone Charger (5V) or the USB port of a computer (5V).
- The board continues to function even at 15V, but there is a slight increase in the voltage. Over a long period, the power regulators are likely to get damaged due to over-heating. It maybe safer to supply approx. 7.5V – 9V to the board for long-term persistent use.
- The board does not feature a cut-off mechanism in case of under-voltage or over-voltage. Most electronic components do not work properly if the voltage levels are not within specification levels. Single board computers like the Raspberry Pi and Arduino in-fact hang-up and require reset.