Wall wart power in Li'lBoard page.
Model number: LB2.08.
Description: Accept the power plug from a plug-in transfomer with one of 5 different size plugs. (5.5 mm OD plug with either a 2.1 mm or a 2.5 mm pin, or a 3.5 mm OD plug with either a 1.3 mm or a 1.3 mm pin, or a 4 mm OD plug with a 1.7 mm pin.)
Applications: Use a readily available “wall wart” (these are called “plug packs” in the UK) as a source of power. These can usually be picked up for a nominal cost at a recycle/re-use type of place. Most are not regulated, so a L'il2.01 or a L'il2.06 following would be a typical configuration. Because the ground plane of L'ilboards are not grounded explicitly, either a negative or positive center plug can be used without having to cut off the wall wart's connector and solder in a new one. Often, more input capacitance will be needed with, for example, a L'il2.01. This can often be installed on the extra terminals of the L'il2.08.
Features:
•The voltage can be switched off-board if desired, or a solder blob at SJ1 can bypass the switch terminal pads.
•Includes an LED power indicator which can easily be disabled.
•The “sense” terminal is brought out. It can be used to indicate to your circuit that a source of power has been connected to the jack in systems where alternative sources of power are available. Since this pin connects to the outer terminal when the plug is absent, normally a pull-up resistor would be used to sense that the plug is absent.
Key components: PCB-mount power jack, one of 5 models.
Restrictions: If a positive ground situation is being created with a center positive plug, then the ground plane of the module must be isolated from the rest of the system. If a center negative input is used, then the LED will not work, and could be destroyed. A jumper area, SJ2, with a normally connected, but easily cut, jumper is provided so that the LED can be easly isolated.
Images:
Click on image for full (PDF) schematic
SPI: N/A.
Tenth centers: YES