User manual

Figure 59: The last residue can be scratched off with a small electronics screwdriver or a needle.
4.16 Completing Transistor Circuit
After soldering the resistors, LEDs and the transistor to the PCB, all you need now is the
battery clip, some wire bridges and a switch. Form the latter from two wire pieces that are
only soldered onto the circuit at one end. strip the free ends a little. Touch them to each
other to close the switch.
The challenge when completing the circuit is in the PCB already being tightly equipped.
You therefore need to be especially careful when you move the hot soldering tip to a new
work-site. If it is still too narrow, you can bend the higher components aside a little.
The circuit shows the basic function of the NPN transistor. There are two circuits. A low
basic current flows in the control circuit, a larger collector current in the load circuit. The
LEDs indicate the currents. The red LED is brightly lit, the green weakly. The basic current
can only be seen as a low light in the green LED in a darkened room. The difference indi-
cates the strong current amplification. .
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