LONG LIFE BATTERY-If after taking the steps described above
If after taking the steps described above
If, after taking the steps described above, a strong signal cannot be generated, all circuits should be checked again.See if the wiring is correct.If the wiring is correct, check whether < is in good condition.This can be checked with a transistor tester and replaced if there is any problem.
The shorter the length of the connecting wire between the preamplifier and the radio, the better.If the connection line is too long, this is often the problem.Also want to find out whether the switch is on.It is also possible that after the switch Si is mounted on the circuit board, it is not clear which direction is on and which is off.
If no problem is found in the inspection, the output voltage of the solar cell can be measured with a voltmeter, which should read just over 1V ( the nominal value is 1.35V DC ).If there is no output voltage, it may be that one of the three solar cells accidentally reverses the polarity so that the output voltage is zero.If the normal voltage is measured on the solar cell, further check whether the positive plate lead is connected to the appropriate position in the circuit.Sometimes the power supply is easily reversed, and the negative lead is mistakenly connected to the positive terminal of the circuit, while the positive lead is connected to the negative terminal of the circuit.Fortunately, in this circuit, if the power supply is reversed, no damage will be caused to the transistor or any other components.Correct wiring of solar cells and electronic circuits can reduce many troublesome problems and enable the circuits to work normally.
4 - 20 FM radio powered by solar cells
Many readers have the experience of installing an ore AM radio and designing and manufacturing a small AM transistor radio.Some of the devices to be introduced in this book, namely this kind of circuit, however, the design layout of the small FM radio is very few.Figs. 4 - 22 show a circuit diagram of a FM radio powered by solar cells.This circuit diagram is capable of receiving broadcasts in all FM bands, as well as the frequencies transmitted by the air tower in the airport, and can also receive all 2 - meter amateur radio communication bands.Due to its small size and simple circuit, this device is not a sensitive FM device, but only a 14 - inch whip antenna can hear the local broadcast very clearly.
All circuits can be powered by solar lighting or other conventional light sources, and two-stage transistor amplifiers are used to increase the output power, which can supply the volume level required for an electronic headset.This receiver is actually a transistor detector, very similar to the power-free crystal receiver described above.However, after the detection stage, it is an amplification circuit powered by a solar cell. As long as a small output signal is provided, the earphone can hear a comfortable sound, so the sensitivity of this FM receiver is much higher than that of ordinary crystal receiver.
Figure 4 - 23 shows the circuit board layout of this FM radio.Coil L3 is a whip antenna using antenna - 14
CI - 10PF Variable Capacitance
CA - 0.025 / ZF15V DC
DI - Ge diode
EPI Microcrystal Headset
LV4I / 4 turn, No. 16 wire, diameter 3 / 4 "
PCV PQ - Micro Solar Cell
ELS 2 - IO1 / 2W Monument Film Resistance
Blow - double - pole single-throw microswitch
Figure 22 Frequency Modulation Radio Circuit Powered by Solar Battery
Figure 4 - 23 FM Radio Circuit Board
Hand - wound, with 16 # tinned copper wire wound around four and a half turns, the four and a half turns are evenly spaced over five-eighths of an inch in length, and the diameter of the coil is three-quarters of an inch. Figure 4 - 24 is an enlarged schematic view of the coil, which can be wound on a cylindrical object such as a pencil or screwdriver.The diameter of the coil form should be slightly less than three-quarters of an inch. After the coil is wound and removed from the coil form, its diameter must be measured.The coil should be wound as close as possible to the specified size.In the future, it can be adjusted by squeezing or pulling the coil closer.When the coil is wound, the coils will abut against each other.After taking off from the pencil mould, U can use the pencil point to pull out each turn of winding until the total coil length reaches five-eighths of an inch. After D is finished, the coil should no longer be in close proximity to each other.
The mounting of electronic components on the circuit board is shown in fig. 4 - 23, and the placement of this component is very similar to that shown in the figure.This arrangement is quite compact in the arrangement of components, and care should be taken to keep the coil away from any metal object.( v is a variable fine tuning capacitor. use a small screwdriver to adjust the capacitor by turning the bolt installed in the center of the capacitor.Screwdriver must be made of plastic, because any metal screwdriver will cause frequency drift when it is close to the coil or electric cellar.Four rectangular solar cells are mounted on the bottom right of the circuit board and then wired as shown.
It must be noted that the connection method of the battery is different from the connection method previously described. The four batteries are divided into two groups, each group is connected with two batteries in series.( the negative poles of and are connected with the two poles;The negative pole of the is connected to the base of the.
The final job is to connect the solar cells to the circuit, but before connecting, turn off the si - be sure to be in the disconnected position.When all wiring work is completed, all wiring must be strictly checked again.Because this circuit is more sensitive than some other circuits, it needs to work strictly according to the normal manufacturing steps.Note that the antenna is connected to the second turn of the coil K, while the lead of the diode is connected to one-half turn on the same side as the two wires.These connections are very important. 0 This must accurately calculate the number of turns. A 14 - inch long hard wire can be used as an antenna.