Solar panel of diodes and transistors
There will always be old ones in the radio designer farm diodes and transistors from unwanted radios and televisions. In skillful hands, this is wealth, which can be used efficiently. For example, make a solar battery with your own hands for powering in the traveling conditions of a transistor radio. As you know, when illuminated with light, a semiconductor becomes a source of electric current - a photocell. We will use this property.
The strength of the current and the electromotive force of such a photocell depend on the semiconductor material, the size of its surface and the illumination. But in order to turn a diode or a transistor into a photocell, you need to get to the semiconductor crystal, but, more precisely, it needs to be opened.
How to do this, tell you a little later, but for now look at the table for home-made photocell parameters.All values were obtained when the lamp was illuminated with a power of 60 W at a distance of 170 mm, which roughly corresponds to the intensity of sunlight on a fine autumn day.
As you can see from the table, the energy produced by one photocell is very small, so they are combined in batteries. To increase the current delivered to the external circuit, the same photovoltaic cells are connected in series. But the best results can be achieved with a mixed connection, when the photobattery is assembled from the series-connected groups, each of which is made up of identical parallel-connected elements (Figure 3).
Pre-prepared groups of diodes are collected on a plate made of getinax, organic glass or textolite, for example, as shown in Fig. 4. The elements are joined together by thin, tin-plated copper wires.
Conclusions that are suitable for the crystal, it is better not to solder, since this can damage the semiconductor crystal due to high temperature. Place the photocell plate in a sturdy casing with a transparent top cover. Solder both pins to the connector - you will connect the cord from the radio to it.
Solar photo battery of20 diodes KD202 (five groups of four parallel-connected photocells) in the sun generates a voltage of up to 2.1 V at a current of up to 0.8 mA. This is quite enough to feed the radio receiver on one or two transistors.
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