1. Making materials
1. 3 npn type low-power transistors, 2 button batteries, 1 100Ω resistor, 1 light-emitting diode, and 1 common test pen.
2. Tools, soldering iron, tweezers, diagonal pliers, multimeter.
Second, the production method
1. Identify components
(1) The triode has 3 pins, which are emitter (e), base (b) and collector (c). There are two types of triodes: npn type and npn type, which have similar functions but opposite current directions.
(2) The light-emitting diode has only 2 pins, which are the positive electrode and the negative electrode. Generally, the longer one is the positive pole and the other is the negative pole. Can not be reversed in the circuit.
2. Cut the leads of all components short, scrape off the oxide layer, and weld them as compactly as possible according to Figure 4.
3. Referring to Figure 5, put the soldered circuit into the electric pen, pay attention to make the A end of the resistor in contact with the metal part of the front end of the electric pen, and the positive pole of the button battery pack should be connected to the metal screw of the end of the electric pen through the spring.
3. Learning to use
1. Electricity measurement by induction method
Hold the electric pen and touch the outer skin of the mains line (not the metal part of the wire) with the front end. If the LED lights up, it means that the contact is the phase wire (live wire), otherwise it is the neutral wire (ground wire). If several lines are not lit, it means there is no electricity.
2. Identify diodes and triodes.
Touch one pole of the diode with one hand and touch the other pole of the diode with the other hand. If the LED is on, it means that the pen tip is touching the negative pole; if not, the pen tip is touching the positive pole. Then reverse the two pins and try again. If the two measurements do not light up, the diode is broken. The method of measuring the triode is similar, it can be regarded as two diodes connected together.
3. Check whether the circuit is on or off and whether there is leakage
On the premise that the line is not connected to the power supply, touch one end of the line with the electric pen with one hand, and pinch the other end of the line with the other hand. The line is connected to the mains, hold the electric pen, touch the housing of the electrical appliance, the light-emitting diode lights up to indicate leakage.
