I have a circuit in which I want the operation of one part to trigger operation of another part. I am using some adafruit sound boards, and I want that while the sound is being played, a set of lights comes on. Poking around showed the right thing for this would be transistors, being electrically operated switches essentially. Logically, everything seems to be working fine, but the light (LEDs) are coming on SUPER dim. It is noticeable that they are on, but they are not actually throwing any light out.
This instagram post shows how I am expecting the 3xWhite LEDs to look. Nice and blindingly bright (the bright spot on the left breadboard). This is with them just hooked up directly to the circuit, before I tried introducing the switching transistor.
This one on the other hand (video) shows how it is actually working. They are functioning logically correct, in that they are turning on while the audio plays, and then turning off when it is done, however they are only just barely turning on, not bright at all.
My first thought was either the LED or transistor-base resistors were providing too much resistance, so I've stepped them both down (originally they were both 220Ω), and even tried taking them out completely. That didn't help at all.
I've also tried a number of different transistors, the TIP102, TO-92, MC16-0100, and an NTE-199, all with the same effect.
My current working theory is that the line the sound board uses to drive the amplifier does not provide enough amps to fully switch the transistor, so it is kind of "partially" closing. I think that may be the case based on this datasheet segment from the sound board (if I'm reading it right). I think I had seen in my google travels that most of these small transistors switch at around 100mA.
I don't even know if that is actually possible though. Can a simple BJT actually be "partially" triggered or is it a strictly binary ON/OFF?
The white LEDs I don't know a whole lot about. They are the original LEDs from the toy I am upgrading. I'm hoping to be able to just use them for the new circuit. Using my multimeter's resistance mode, they come on at 200 and 2000 ohms, but nothing above that.
Any other ideas or feedback? I could ultimately move the 3xWhite LEDs onto the trigger switch circuit without the transistor, but then they are just on/off depending on the trigger. I am really hoping to get them to stay on as long as the sound is playing, even if the trigger is released.