Medical Technology badge instructions

This should be the contents of your kit.

Begin by carefully cutting the boards out making sure not to bend
the boards.
DO NOT USE NICE SCISSORS! This will wear them out pretty fast.
The IKEA scissors are about 3 SEK and are good enough.
This step could also be performed with other tools if you have access to
them and the knowledge to use them.

Begin on the reverse side.

Tin one of the pads for each resistor and also for the capacitor.
I find it easiest to use 0,3-0,4mm leaded solder and a fine iron tip.

Reheat the solder with the soldering iron and place the components
correctly into the melted solder.
There are 24 resistors and 1 capacitor.

Solder the other end of all the components.

Turn the board over.

Tin one of the pads for each LED, i suggest the pad in contact with
the copper plane (this is not the way I did it in the picture).

LEDs usually have some kind of marking to show their polarity, at
least on the bottom but often also on the top. All the LEDs in the
picture are turned with the cathode down.

LEDs where markings are missing or hard to see can be tested by
using a multimeter. The multimeter is set to diode test mode and the
probes are touched to the connections on the LED. In this picture the
black probe (negative) is on the lower side and the red probe (positive)
is on the upper side.

Solder all the LEDs with the anode towards the copper plane which means
the cathode marking is facing towards the via (the hole where the signal
goes through the board).

If you are unsure which side is which you can use a multimeter to measure
which pad is connected to the top plane and/or look at this picture.

Solder the other end of all the LEDs.

You can now test run the badge by setting the voltage of a lab
power supply to 3-5V and the current to zero. Connect test clips according
to the picture and turn the current limit up very carefully. If the
badge draws more than 0,1A something is wrong, for example a short
in a solder joint.
If you find it hard to attach the test clips do this test after the next step,
solder the 3 wires first and use them to connect the clips

Straighten the 3 circular wire pieces and solder them according to the picture.

Thread the middle board onto the wires as shown. This should be the board
without pads for a brooch pin on the other side.
Solder the connections to the wires in the 3 places.

Place a CR2032 or other 3,2mm thick 20mm diameter object according
to the picture.

Mount the last PCB according to the picture, note that the two
square areas should be turned outward.

Solder the 3 wires to the back PCB while pushing gently down on the PCB
to make sure the battery sits nice and snug.

Cut off any protruding wire ends.

If desired the pin carrier can be cut in two to be used as a switch,
note that about 2-4mm of the center of the carrier needs to be removed
to allow for a gap in the middle.


If you choose to not cut the pin carrier the badge is instead turned off by
removing the battery.

Remove the battery and solder the brooch pin in place.
This step requires a lot of heat, a good method is to place the pin in position
on the board, place your iron tip in the center of a hole in the pin, add a
small amount of solder to the point where the pin, board and iron meets. Then
give the board and pin a good 10 seconds to heat up before trying to add more solder.

Wear the badge in a visible location and use a non-depleted battery
at every following student event!

Eagle files and AVR code

Latest update 2017-03-23