|Here all the through-hole components are soldered on the|
|Here is the half of the SMD components soldered on.|
|Looks okay upon a quick check.|
|First LED works! Ground is connected in the DIP 8 socket|
on the other side.
|Two of them work! (By the way, that is Sculpey acting as|
a third hand)
|All together, a suspicious lack of brightness.|
|All of the LED's are functioning...|
And this is when I realized my mistake. The thought came to me, and I whipped out my multimeter. Before the first LED, the voltage was 4.9, about the same as the five volts I had given it. After the first one, the voltage was 3.6. Guess what? After the second, it was one volt. Why did this happen? It's called voltage drop. It is a property of diodes, LED's (after all, they are diodes), and transistors. Every LED has a voltage drop, sometimes called Forward Voltage Drop on a datasheet.
So, I still have to get this to work. It is a present for a friend who is going to boarding school and he is leaving in a few days.
|This is what the schematic used to be...|
|This is it with a few tweak on the one side. One is a solder bridge|
to ground and one is a jumper to a digital pin.
|All done! There is a similar correction on the newly|
This is one of the reasons that prototyping is so great. Had I just simulated this on SPICE or something, I would have rearranged it before etching and it would have looked great. But this way, it still works, and I gained some experiential knowledge about voltage drop. A good lesson learned.
Of course, the next step is to program it...