Introduction: No Resistor 2N3904 Triggered IR LED Breadboard Array
The breadboard wired up and a small button 3 volt cell triggering the array which runs off the 9 volt battery.
Step 1: Wiring
Each group of 4 LEDs is in series, the positive lead of the top LED is connected to the negative lead of the one below it.
Since each LED is attached to two rails on the perf board the 4 LED cell of the 5 cell array ends up in series.
In this pic the negative side of the LEDs are up. There is a flat side on the LED which tells you it is the negative lead.
Each of the 5 cells is then wired in parallel using the power rail to the right of the board. Simply wire the top rail of each 4 LED cell to the + rail and the bottom rail of each 4 LED cell to the - rail.
The 2N3904 Transistor does the switching. I won't go into theory here.
When facing the Transistor with legs down and the flat face towards you do the following.
Left leg to 9 volt battery negative
Middle leg to left + signal rail
Right leg to the right - power rail
Right leg also wired to the left - signal rail
You will also have to connect the positive lead of the 9 volt battery to the + power rail on the right side of the board. I could have done it directly but for some reason I hooked the lead into a perf rail and then used the blue jumper to go to the + power rail.... I think it just was more tidy.
Please note the two small orange jumpers on the left side of the board. This is to make that rail cover the whole left side of the board since those rails are split in the middle. I didn't bother jumping the right rail since no wires are needed in the bottom of the right rails.
I salvaged the LEDs from an IR array that didn't work, they are just barely long enough to stick into the perf board. I tested each LED with a 3 volt CR2032 coin cell battery. This confirmed polarity and function. Since the IR light is invisible I had to observe them while looking thru a cell phone camera which can see the light.
Step 2: More to Come....
If all is wired properly a small input voltage into the two wires on the left rail will trip the 9 volts and power the array. I hope to add the TVBGone software to the Nano or wire in a learning TV remote to the signal wires. To hook up the learning remote I will remove the IR LED from the front and attach my signal wires ( + & - ) to where the LED's + and - leads were in the remote. I hope you find this useful.