Conrad Course material 3964 14 years and over 3964 User Manual

 

3

 

Fig. 4: Schematic symbols for various batteries (Bat.gif)

 

 
Light-emitting diodes 
The educational kit contains two red LEDs and a green and a yellow LED. With all LEDs, the polarity must always be 
attended to. The negative terminal is called the cathode and is on the shorter connection wire. The positive terminal is 
the anode. Inside the LED, you can see a cup-like holder for the LED crystal which is at the cathode. The anode 
terminal is connected to an extremely thin little wire with a contact on the top of the crystal. But in contrast to 
incandescent bulbs, LEDs must never be directly connected to a battery. A series resistor is always necessary.

 

 

 

Fig. 5: The LED (B_LED.gif)

 

 
Resistors 
The resistors in the educational kit are carbon film resistors with tolerances of 

±5%. The resistor material is attached 

to a ceramic bar and covered with a protective layer. Labelling is done in the form of coloured rings. Next to the 
resistance value, the accuracy class is also indicated. 

 

 

 

 
Fig. 6: A resistor (B_Widerstand.gif) 
 
There are resistors with a tolerance of 

±5% in the values of the E24 series, with each decade containing 24 values at 

an approximately uniform distance from the adjacent value. 

 

 
Table 1: Resistance values according to the E24 series 
 
1.0  1.1 

 1.2 1.3 1.5 1.6 

1.8  2.0 2.2 2.4 2.7 3.0 
3.3  3.6 3.9 4.3 4.7 5.1 
5.6  6.2 6.8 7.5 8.2 9.1 
 
 
The colour code is read based on the ring that is closer to the edge of the resistor. The first two rings stand for two 
digits, the third for a multiplier of the resistance value in ohms. A fourth ring indicates the tolerance.

 

 
Table 2: The resistor colour code

 

 
Colour

 

Ring 1 
1st digit

 

Ring 2 
2nd digit

 

Ring 3 
multiplier

 

Ring 4 
toleranc
e

 

Black 

 0 1 

 

Brown

 

1 1 10 

1% 

Red

 

2 2 100  2% 

Orange

 

3 3 1,000  

Yellow

 

4 4 10,000 

 

Green

 

5 5 100,000 

0.5% 

Blue

 

6 6 1,000,000 

 

Violet

 

7 7 10,000,000 

 

Grey

 

8 8  

 

White

 

9 9  

 

 

 

 

 

 

Gold

 

  0.1  5% 

Silver

 

  0.01 10% 

- Cathode 
+ Anode 

    A    C 

1.5 V     4.5 V     6 V     9... 12 V