A Switched LED Circuit
A. Breadboard view of an Arduino Nano connected to a breadboard. When plugged into a USB port, this board will supply 3.3V across the voltage and ground buses.
( I chose this way because I didn’t have enough battery.)
B. DC voltage jack and 7805 voltage regulator on a breadboard. The regulator is supplying 5V and ground holes are supplying voltage to the rest of breadboard.
Add an LED and a 220-ohm resistor to the breadboard. A DC power supply of 8-12V is connected to the input and ground of a 7805 5V voltage regulator. The output of the regulator is connected to a pushbutton. The other side of the pushbutton is connected to one side of a 220-ohm resistor. The other side of the resistor is connected to the anode of an LED. The cathode of the LED is connected to the voltage regulator’s ground connection.
My work
After three attempts the light turned on, I found out that Led's long side was positive and the left side was negative.
Components in Parallel/Measuring Amperage
This is the same circuit as shown in 1-2, but the anode of one LED has been disconnected and then connected to one lead of a meter measuring amps. The other lead of the meter is connected to the junction between the resistor and the anodes of the other two LEDs.
My work
The voltage was weak, so the LED was lit very weakly (needed adding up voltage). The funny thing is, when I used green and red leads instead of two red leads, the lights didn't turn on. (still I don’t know why)
The brightness of the LED light connected in series was very weak, so it was much brighter when connected in parallel.