The transistor – part which serves for strengthening of electric signal. Thanks to the properties the transistor can be used for designing of the simplest temperature recorder. Such sensor can be used in simple self-made devices where temperature monitoring of the environment is required.
- Germanium transistor
1. One of transistor parameters important - reverse current of the collector. Reliability of operation of the designed device depends on its stable work. The reverse current of the collector appears at connection of source to collector junction in the opposite direction.
2. To make sure, current at change of surrounding temperature is how stable, it is necessary to have two transistors – one germanic, and another silicon. Also the ohmmeter and glass of warm water is required (50-60os).
3. Connect to conclusions of the collector and base ohmmeter so that the positive probe of ohmmeter has been connected to conclusion of base. The arrow of the device at the same time will record the reverse resistance of collector junction depending on reverse current of the collector. Resistance can be big and reach several hundred kOhm.
4. Lower the transistor in water hat down so that the transistor basis with conclusions was above height of water on 3 mm. In several seconds controlled resistance on ohmmeter will begin to decrease. In minute it can fall very strongly, it depends on water temperature.
5. If you take out the transistor from water, then resistance will change, the arrow of ohmmeter will return to initial situation.
6. When carrying out experiment with the silicon transistor you will notice that the reverse current of the collector will practically not be defined by the device. Fluctuations of reverse current of the collector are less notable cascades from silicon transistors in comparison with germanic. Therefore when developing the radio equipment preference is given to silicon transistors.
7. As the reverse current of the collector depends on surrounding temperature, the germanium transistor can become basis for designing of the temperature recorder used in various radiotehnical devices. For this purpose it is necessary to graduate only ohmmeter scale according to indications of the thermometer.