Table of Contents
How does a voltage transistor work?
The transistor works as an open switch. As a consequence, the output voltage is equal to the voltage source Vcc. Injecting enough current into the base, a current flows from Vcc to the ground and the output voltage is the same as the ground, i.e., the transistor works as a closed switch.
What is a transistor voltmeter?
Transistor Voltmeter(TVM): The dc input is applied to a range attenuator to provide input voltage levels which can be accommodated by the dc amplifier. The input stage of the amplifier consists of a FET which provides high input impedance to effectively isolate the meter circuit from the circuit under measurement.
How do voltmeters work?
A voltmeter is an instrument that measures the difference in electrical potential between two points in an electric circuit. An analog voltmeter moves a pointer across a scale in proportion to the circuit’s voltage; a digital voltmeter provides a numerical display.
How does a transistor control voltage?
The transistor allows you to control a circuit that’s carrying higher current and voltage from the a lower voltage and current. It acts as an electronic switch. When there’s no voltage difference between the base and the emitter, the transistor turns off, or stops the flow of electricity from collector to emitter.
What are the specifications of voltmeter?
DC Voltmeter
| Description | Moving Coil Meter of 90° or 240° Deflection with Fixed / Interchangeable Scale Facility |
|---|---|
| Movement Type | Moving Coil permanent magnet type, with Jewel Bearing Suspension |
| Range | Voltage m V: 0-50 m V to 0-600 m VVoltage V: 0-1 V to 0-1000 V |
| Size | 48 x 48 mm, 72 x 72 mm, 96 x 96 mm, 144 x 144 mm |
What are the two specifications of electronic voltmeter?
The general specification of digital voltmeter are given below, Input range : The digital voltmeter has automatic range selection facility. The input range is from ± 1 V to ± 1000 V. Accuracy : The accuracy is about ± 1 percent for a 3 digit digital voltmeter and ± 0.0002 percent for a 6 digit digital voltmeter.
How is a voltmeter constructed?
Parallel connection is used because a voltmeter is constructed in such a way that it has a very high value of resistance. If it is connected in parallel, than the load impedance comes parallel with the high resistance of the voltmeter and hence the combination will give almost the same the impedance that the load had.
Does transistor control voltage or current?
The Field Effect Transistor is a voltage controlled device, because the drain current depends on the negetive voltage ( by convention) applied at the gate. The BJT (Bipolar Junction Transistor), on the other hand, is a current controlled device, since the collector current depends on the base current.
Transistor voltmeters can be designed for measuring very high voltages such as hundreds or thousands of volts. Owing to amplifying properties electronic instruments possess very high sensitivity and because of high sensitivity, their input impedance is increased. It results in reduced loading effect while carrying out measurements.
What is an electronic voltmeter circuit?
Electronic Voltmeters. In all electronic voltmeter circuits the principle involved is that an indication on a permanent magnet moving coil instrument (normally abbreviated as PMMC or D’Arsonval movement) proportional to the input voltage is obtained by means of amplification in one or more stages with a high input impedance.
Why do electronic voltmeters have high input impedance?
Electronic Voltmeters. So electronic voltmeters draw very low power from the test circuit and it can be said that it has very high input impedance. This feature of electronic voltmeters is indispensible for voltage measurements in many high impedance circuits such as encountered in communication of the order of micro-volts.
Why does a voltmeter measure voltage in a parallel circuit?
Also in parallel circuit we know that the voltage is same so the voltage between the voltmeter and the load is almost same and hence voltmeter measures the voltage. For an ideal voltmeter, we have the resistance is to be infinity and hence the current drawn to be zero so there will be no power loss in the instrument.