Electronics Tutorial

Welcome to the electronics tutorial! If you want to learn electronics, it's a great place to start. You can also revise for your GCSE here, as it's written to GCSE standard for the year 2000 (so if you're taking it in 1999, forget it. but have a look anyway!). It's suitable for all, and anyone can learn electronics using a combination of this & the other material available on my site. Whether you want to learn as a hobby, are taking a course in it, or just want to brush up on a few points, there should be something here to help you.
If you have any questions about electronics, this tutorial, or just fancy a chat, you can e-mail me on alex_tb@hotmail.com . If you've got a PhD in electronics or something, & you think I've stated something wrongly in here, please e-mail me & tell me about it, so I can correct it.

Note that the electronics tutorial is 1998 Alex Pounds. All rights reserved.

  1. Electronic systems
  2. The resistor
  3. Current
  4. Resistances in series
  5. Parallel circuits
  6. Parallel circuits experiment
  7. Resistors in parallel
  8. Power & energy
  9. Digital & analogue voltmeters
  10. Logic - Digital electronics
  11. The potential divider
  12. Measuring potential dividers
  13. Using different voltmeters
  14. The potentiometer
  15. The Light Dependent Resistor
  16. The Thermistor
  17. Binary numbers
  18. The Seven-segment display
  19. The Binary Coded Decimal (BCD)
  20. Diodes
  21. Which indicator?
  22. Switches
  23. Transistors
  24. Integrated Circuits
  25. The relay
  26. The Capacitor
  27. The bistable (latch)
  28. The Astable (or pulse generator)
  29. The Cathode Ray Oscilloscope (CRO)
  30. The 555 timer as an astable
  31. The monostable multivibrator
  32. The 555 timer as a monostable
  33. Alarms
  34. Alternating voltage and current (AC)

 

1. Electronic systems

 

All circuits can be designed as a system.

eg. a radio receiver

Radio

The processing can the be further subdivided:

 Subdivided radio

 

Each block can then be designed in isolation, and the blocks coupled together. We need to know the input & output properties of each block, but no details of how they work.

NB. Each block also needs a power supply input, but this is not normally shown on the diagram.

 

2. The resistor

 

A resistor has a resistance, which is measured in ohms. If you haven't got the symbol font installed, the following character will not display correctly - W . This is the symbol for Ohms.

Wire wound resistor

 Wire wound resistor

Carbon film resistor

 

 

Production spread

 

Colour coding

Black 0
Brown 1
Red 2
Orange 3
Yellow 4
Green 5
Blue 6
Violet 7
Grey 8
White 9

Colour code guide

Band 1 = First digit of resistance
Band 2 = Second digit of resistance
Band 3 = Number of following zeros
Band 4 = Tolerance

Tolerances

No band = 20 %
Silver = 10 %
Gold = 5 %

 

The resistor printed code

R = ohms
K = thousands of ohms
M = millions of ohms

The position of the letter determines the decimal point.

1800 = 1K8
120 = 120R

Tolerances are shown by using postfixes:

J = 5 %
K = 10 %
M = 20%

So:

56000 10 % = 56K0K
6800000 5 % = 6M8J

 

3. Current

Voltage = Current x Resistance
V = I x R
Volts = amps x ohms
Volts = milliamps x kilo ohms

NB. 1mA = 0.001 A
1 Kilo ohm = 1000 ohms

 

4. Resistances in series

R1 R2 V1 (V) V2 (V) V3 (V) VT (V2+V3)
2K2 3K3 15.12 6.50 8.60 15.10
4K7 1K2 15.12 12.08 3.04 15.12
270R 150R 15.12 9.25 5.84 15.09
39K 69K 15.12 5.46 9.61 15.07

 From this experiment, we can conclude:

 

5. Parallel circuits

The 2 circuits on parallel each have 9V across them.

I1 = V / R = 9 / 10 = 0.9 mA

I2 = V / R = 9 / 0.3 = 30 mA

So the total current from this battery is 30.9 mA. Note that the resistance for the second half of the circuit = 300R = 0K3 , because 200 + 100 =300 .

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