Free Electronic Circuits & 8085 projects

Electronic projects with circuit diagram and 8085 microprocessor projects.

Sound electroscope

Published on Mar 16 2011 // Instrumentation and Tester Circuits

The electroscope is a test sound 220V AC small FireWire devices. Shi Dianbi built with traditional neon bulb and resistor, the use of neon light bulb can detect and display circuit which is charged FireWire root. Weak neon light bulbs, general lighting during the day in the outdoor neon bulb is difficult to see whether the light, make a sound if the electroscope, you can use voice prompts to tell us which of the root line is live firing.
First, the components of the preparation
The electroscope is a test sound 220V AC small FireWire devices. Shi Dianbi built with traditional neon bulb and resistor, the use of neon light bulb can detect and display circuit which is charged FireWire root. Weak neon light bulbs, general lighting during the day in the outdoor neon bulb is difficult to see whether the light, make a sound if the electroscope, you can use voice prompts to tell us which of the root line is live firing.
First, the components of the preparation
Single strand insulated wire leather 5-10cm
Buzzer used here is essentially a built-in integrated circuits of small speakers. Its small size, easy to use. Must pay attention to the buzzer with the polarity of lead, can not take the wrong. It is positive then the power of positive and negative power supply is the negative. Many different types of buzzer, buzzer voltage there are several, such as 3V, 6V, 9V and so on. Used here is a small continuous sound of the buzzer, and its working voltage is 3V, the operating current is about 20mA. There is also a buzzer sound is intermittent, the voice sounds good, but the price is slightly expensive.
Second, the production and commissioning of the circuit
First of all the components of the inspection, the buzzer as shown in Figure 2-1, the positive and negative poles 3V power supply positive and negative, should be the normal sound the buzzer.

Sound electroscope circuit 1

Figure 2-1 Connect the buzzer
Many different types of transistors, look different, as shown in Figure 2-2 is the most common transistor circuit symbol and the plastic pipe used in the physical map. Transistor before installing all the pins will be identified. When the pin down with words for their own plane, the pin from left to right emitter (e), base (b) and collector (c).

  Sound electroscope circuit 2

Figure 2-2 Transistor symbols and in-kind
Lead components used in the installation should be carried out prior to soldering tin processing. If the components of the lead has oxidized hair black, need to use a knife to shave the lead parts, and then the tin processing, this leads after treatment to ensure the reliability of the welding quality. For starters, we must develop good habits and do a good job installing the preparation prior to welding. Preparation work is completed, the electrical control electroscope sound principles of Figure 2-3, Figure 2-4 to install circuit board and circuit board components in Figure 2-5, followed by the resistor, capacitor, transistor and buzzer mounted to the board and welded on solid. The insulation of a wire with both ends of the strip 5mm, the end of the welding in the input audio electroscope (ie the resistor end). Finally, solder the battery clip leads to the circuit board, pay attention to the battery positive and negative leads the folder must be correct.

Sound electroscope circuit 3

Figure 2-3 Circuit Diagram sound electroscope

 Sound electroscope circuit 4

Figure 2-4 Circuit Board Installation Chart
When testing the insulation of a long wire with a touch AC power outlet in the firing line (to the absolute attention to safety, Shi Dianbi neon bulb can be used prior to a good line of fire and zero line) hands touch the battery positive or negative, the buzzer should send tweets. Because electroscope test is 220V AC, so be very careful.
Figure 2-6 is a small piece of 43mm × 1Omm electroscope sound board diagram for reference. This can be done in this circuit is very small. Circuit board using a two button batteries, map location has been reserved, but requires self-made battery clip, pay attention to button battery case is the battery positive terminal.

Sound electroscope circuit 5

Figure 2-5 Component diagram board

Sound electroscope circuit 6

Figure 2-6 electroscope small audio circuit board map
Third, the circuit works
See Figure 2-3, the circuit resistor R is a limiting protection resistors to avoid injury testers. Since the resistor values ​​are too, VT1 transistor base current is extremely small, a transistor can not drive the buzzer, so with the two transistors. So that when the left end of resistor exposed to 220V AC, the AC signal through the resistor into the transistor base, but also by the body back to earth. Two transistor the signal is amplified to drive a buzzer. Capacitor C1 is to eliminate all interference set. Buzzer does not work, the circuit is not power.
Electroscope in 2.7MO resistor values ​​can not be too small, or use unsafe.
Electroscope sound simple, but can also use this circuit to do other purposes. Figure 2-7 is indicative of a touch doorbell schematic diagram on the left is a pair of touching film. Using the body’s own resistance to trigger the circuit. Think about what else this magical effect of the circuit

Sound electroscope circuit 7

Figure 2-7 Touch doorbell circuit