To configure electronic devices and reconcile electrical circuits, you need to know the resistance of their elements.
Sometimes it also becomes necessary to check the individual radio engineering elements (resistors, diodes, transformers of different purposes) for resistance.
You will need
- - Ohmmeter-
- - Ammeter-
- - The voltmeter-
- - Knowledge of Ohm's Law.
The detail or element examined in resistance, Disconnect from the circuit. Start the measurement by turning the device on to the minimum resistance measurement mode. If the readings of the instrument are not sufficiently readable, it is possible to switch stepwise to the mode of higher resistance values. Each measuring device has probes, which they attach to the terminals of the parts. Before making a measurement, it is necessary to read the instruction, especially as regards the observance of polarity. Polarity is important when measuring the resistance of semiconductor parts.
A conventional tester (an avometer) can be measuredThe range of resistances from units Om to units mOhm. For higher impedances, additional DC power connection is required according to the instructions to the device. You can apply the calculation of the resistance of the circuits. To do this, include the investigated part in the circuit with the current source, the ammeter is connected in series with it, and the voltmeter is parallel to the part under investigation. In this case resistance Is calculated by the formula: R = U / I, where R is the voltage, U- resistance, And I is the current in the circuit.
Some radioelements (for example, semiconductors) have different resistance At different directions of the current. This must be taken into account when measuring, by measuring the reverse current at lower values of the applied voltage. Otherwise, the investigated part can fail.