These pages have become a valuable source for learning and understanding electronics.
You will find answers that have never been covered in any text book. 
For this reason we have decided to produce an index so you can quickly locate some of the things we have covered.

Adjustable Regulator -  how NOT to adjust a regulator  Never leave the Common pin floating.
Adjustable Voltage - more advice on how NOT to adjust the voltage on a 3-terminal regulator
Biasing Resistors - notes on Biasing Resistors
Car Interior Light
Current - showing the direction of CURRENT-FLOW
Current - how to measure current
Diode  - Measuring a diode
Faulty Design  - how to design a circuit correctly and see faults in a circuit.
Flip Flop using CD4011 IC
Hearing Aid - A Hearing Aid circuit with a number of faults.
A Joule Thief Circuit - designing a Joule Thief Circuit
Key Hole Light - the circuit flattened the batteries in 2 months!
LED Current - the current through a LED
LED Dice  - A badly-designed circuit is discussed.
LED Flasher - an emitter-follower is not a good idea.
LED Flashers - designing a LED Flasher circuit
LEDs in Series
LED Voltage Indicator  - resistor values to turn on LEDs in a "staircase."
Mat Switch  - Don't use a 555 - It wastes 10mA!!
Motor Driver 
Music Chip - the need for a current-limiting resistor
Night Light - improving the circuit
Oscillator Circuit - how the feedback osc works - it uses a 2-transistor high-gain amplifier.
Oscillator Circuit -
Oscillator - How NOT to design an oscillator circuit.
Power Failure Alarm - see the circuit for the fault.
Push Pull - helpful advice on designing a PUSH PULL output.
Sawtooth Waveform
Sound Meter  - faults with a microcontroller circuit
Stop Resistor  - the important of a Stop Resistor
Stress Meter - Learn about unnecessary components in a circuit.
Thermal Conduction - a very good article to show how to design tracks on a PC board.
Touch Switch - How to design a Touch Switch circuit.
Tracking Transmitter - designing a tracking Transmitter circuit
Turn ON - designing a Turn ON circuit
Voltage Doubler - using a 555 and how to reduce the number of components.
Water Detector -
Wind Turbine Water Heating -  
UM 3561 4-Sound IC -
1k Load Resistor -
designing a circuit correctly
2 Digit Display  -
how to drive 7-segment displays
12v Adapter -
the need to show component values
56R - a badly designed circuit with a 56R wasting current ALL THE TIME. 
500mA - the circuit states 800mA but the transistor will only deliver 100mA.