Solar energy is inexhaustible source of energy. Solar (or other light energy) is converted to electrical energy directly to the device, known as solar cells. With energy conservation and environmental awareness growing, solar is the energy-rich, pollution-free, long life and easy maintenance and reliable performance, and more and more popular. Hands-on production of a small solar battery-powered AM radio wave, is so interesting and pleasant thing: in the sun during the day, night light, you can use it to listen to news broadcasts, learn a foreign language. Through the production, you can master and learn more about solar cells, knowledge, broaden horizons for the future of human development and utilization of solar energy to further lay the foundation.
First, the working principle
Small solar radio circuit shown in Figure 1. It uses a tiny radio frequency application specific integrated circuit amplification and detection to do A, followed by two transistors VT1, VT2 for low-frequency amplifier and emitter, and finally to promote low-impedance 😯 Ear buds playback.
A (model YS414) is a direct amplification detection-radio-specific integrated circuit, which uses TO-92 type plastic packaging, the packaging form of an ordinary 9014-type plastic transistor low power exactly the same shape and pin arrangement shown in Figure 2 (a) below. The pin function: G feet for a public ground, I input pin, O pin as output. YS414 integrated circuit inside the nine transistors, 16 resistors and 4 capacitors formed features include a high impedance input buffer, three high-frequency amplification and a detector, its internal circuit diagram shown in Figure 2 (b) of the instructions. YS414 integrated circuits with high input impedance, gain a large power consumption, fewer external components, the circuit without debugging features, very suitable for the production of micro-simple radio.
Second, the component selection
BP with size of about 35mm × 10mm, open circuit voltage = 2V, short-circuit current = 8mA finished solar panels. The use of solar panels made of silicon chip technology, photoelectric conversion efficiency and stability, has been widely used in calculators and other low current appliances. Solar panel power output capability is closely related to its size, the larger the area, in the same light conditions, the greater the output power. The main advantages and disadvantages of solar panels from the open circuit voltage and short circuit current of these two indicators. Amateur test method is: the solar panels on the environment, direct sunlight, measured with a multimeter across the output voltage, open circuit voltage can be considered; then multimeter directly across the solar panels at both ends of the measured output current , that is considered a short-circuit current.
If not a moment to buy solar panels, can be used three dimensions 10mm × 5mm, open circuit voltage 0.5 ~ 0.6V, short-circuit current = 9mA the 2CR32 silicon photovoltaic cells in series instead. This form of silicon photovoltaic cells as shown in Figure 3, appear before it by the light blue and black, above a few silver grating, leads to two wires as cathode; backlight appear before silver (tin), leads to two wire as the battery anode.
A tiny radio with YS414-type-specific integrated circuit. Its main characteristics: low voltage in the 1.3 ~ 1.5V can be satisfied with the work; power consumption, no signal about when the working current of only 0.4mA; frequency band, up to 150 ~ 3000kHz; zoom capability, the power gain up to 72dB, automatic gain control range of up to 20dB. Internal circuitry and functions with YS414 identical, but different manufacturers of such integrated circuits as well: D7642, TA7642, CTC7642, YS7642, BS414, MK-484, 2N414-type and so on, they can be used interchangeably.
Transistors VT1, VT2 are using 9014 or 3DG8 low-noise low-power silicon NPN transistor, requiring the current amplification factor ß VT1 values between 40 and 150, VT2 ß value of between 20 to 60.
Magnetic antenna winding L to be their own, specific ways: by f0.15mm high-strength single strand wire, the wave in the f5mm × 35mm magnetic bar on a single circle can be tightly wound 82. The attention around the system, for the ghost off the coil, apply Quick Adhesive (or wax) to the beginning and the end of cement to live. Convenient for debugging, before the wound is best to use cardboard to make a coil framework, so that the coil can be made on a bar magnet and move around.
C1 use 5 ~ 200PF ultra-small sealed variable capacitor; C2, C3 and C6 are using ceramic capacitors CT1-type; C4, C5 are used CD11-10-type electrolytic capacitors. R1 ~ R5 used in all RTX-1/8W carbon film resistors. RP WH15-1A-type selection switch for small non-synthetic carbon film potentiometer. XS selection CKX2-3.5-type (f3.5mm diameter) earbuds commonly used two-core jack. Headset with CSX2-3.5-type (f3.5mm) two-pin plug of the low resistance 😯 Ear buds.