MAP4 is a simple “Learn to Solder” badge. We will be using it (hopefully) during Mitch Altman’s visit to the Asylum in June. “Hopefully”, because I’ve ordered 50 boards from PCBpower, but their turn around time is always unpredictable.
The circuit is extremely simple. One CR2032 Coin Battery. Three LED’s. And three current limiting resistors.
The LED’s can be either 3mm or 5mm, clear or diffuse, of any color (Red, Green, Yellow, White, Blue).
It’s also possible to use Blinking LED’s. Board size is 50mm x 50mm.
The resistors are important for several reasons. Some of the colors (Red, Green) have a low forward voltage (about 1.7 Volts) and it definitely helps to limit current. Even with the other LEDs that require almost 3V forward voltage drop, it is still recommended to use a limiting resistor. Adding the resistors extents battery life to several days, compared to just a few hours without the resistors. Here’s a nice analysis of LED Throwies by the folks at EMSL : http://www.evilmadscientist.com/2009/some-thoughts-on-throwies/
For attaching a Safety Pin, the board has four small solder pads. Two component leads cut off from the Resistors are bent in to a “U” shape and soldered on to the board along with the Safety Pin. There’s also a 3mm hole in case some other means of fixing needs to be used.
Design files are available from the Github repository at : https://github.com/MakersAsylumIndia/MAP4