1.5V battery tester circuit using LM324 - ElecCircuit.com
Simple LED circuit with 9V battery – helloCircuits!
Basics: Picking Resistors for LEDs | Evil Mad Scientist Laboratories
UW-Madison MRSEC
UW-Madison MRSEC
Blinking LED Circuit with Schematics and Explanation
Simple Basic LED Circuit (How to Use LEDs) : 4 Steps - Instructables
LED wiring questions with 9v battery as power source - Electrical Engineering Stack Exchange
Arduino 9v power supply - CircuitLab
Simple Basic LED Circuit (How to Use LEDs) : 4 Steps - Instructables
low power - Circuit with 10 LEDs with 9V battery - Electrical Engineering Stack Exchange
File:9v battery and led circuit components (wires, battery, LED, resistor).jpg - Wikimedia Commons
low power - Circuit with 10 LEDs with 9V battery - Electrical Engineering Stack Exchange
LED Strip works powered via USB but not 9V battery - General Electronics - Arduino Forum
MEMO BOARD - FLASHING LIGHT CIRCUIT
Which Resistor Should I Use with my LED? – Kitronik Ltd
paper circuits
9-volt battery connected to transistor controlling LEDs with Arduino - Electrical Engineering Stack Exchange
Simple LED circuit with 9V battery – helloCircuits!
9V Battery Backup Circuit using LM7809
LED Strip Light Internal Schematic and Voltage Information | Waveform Lighting
low power - Circuit with 10 LEDs with 9V battery - Electrical Engineering Stack Exchange
Basics: Picking Resistors for LEDs | Evil Mad Scientist Laboratories
Simple nicad battery charger circuit by little part - ElecCircuit
Circuits From Scratch | Let's Put LEDs in Things! | Adafruit Learning System
