Will_W_76

Hello. There are several comments below that discuss ways to get more power out of this system. Check those out.

Using a 12V battery should be fine. You will just want to double-check that each of your components can withstand the voltage and current they will experience. You can find this information in the datasheet for each component. If it looks like there may be an issue, you can increase the 220Ω resistors (the current-limiting resistors) to a value that will ensure a safe level of operation.

Depending on the specific photo-transistor you are using, the LED can turn on because of the photo-transistors response to light in your environment (sunlight or even fluorescent or incandescent light). What is likely happening is that these other light sources are "turning on" your circuit. Then when you cover it, the photo-transistor no longer sees the external light and turns off. Additionally, it appears that the light emitted from your IR LED is not the proper wavelength (or your IR LED is not on). Otherwise, the LED would remain on when covering the sensor. Verify your IR LED is actually on, and also make sure it emits the wavelength of light that the photo-transistor is best set to receive. Lastly, eliminate the source of external light that is currently turning the cir...

Depending on the specific photo-transistor you are using, the LED can turn on because of the photo-transistors response to light in your environment (sunlight or even fluorescent or incandescent light). What is likely happening is that these other light sources are "turning on" your circuit. Then when you cover it, the photo-transistor no longer sees the external light and turns off. Additionally, it appears that the light emitted from your IR LED is not the proper wavelength (or your IR LED is not on). Otherwise, the LED would remain on when covering the sensor. Verify your IR LED is actually on, and also make sure it emits the wavelength of light that the photo-transistor is best set to receive. Lastly, eliminate the source of external light that is currently turning the circuit on. If it's something else, you can let me know.

Yes, that can be done. The main thing you would want to verify is how much current you are using though. With each "cluster" you are adding additional current to your circuit. Soldering together individual clusters that share a ground and power line is fine, there would be no reason the resistors wouldn't work the same way (as long as they were wired properly in their individual portion).