It is possible to learn resistor resistance, having connected to it an ohmmeter. If such device is unavailable, connect the resistor to a current source, measure value of current in chains and tension on the resistor. After that calculate its resistance. If codings or color strips are caused on the resistor, determine resistance by them.
It is required to you
- ohmmeter, voltmeter, ampermeter, caliper, table specific resistance of substances
Instruction
1. Determination of resistance of the resistor device. Attach an ohmmeter to the resistor and take readings from its screen. Instead of an ohmmeter it is possible to use a multimeter with the corresponding settings as measurement and sensitivity.
2. Definition resistor resistance ampermeter and voltmeter. Collect an electrical circuit which includes the resistor with consistently attached ampermeter and parallel to attached to it by the voltmeter. Connect a chain to a source of current and measure value of current in amperes (ampermeter) and tension in volts (voltmeter). For obtaining value of resistance divide tension into the current (R=U/I). Receive result in Ohms.
3. Determination of resistance of the resistor by codes. If figures and letters are applied on the resistor, with their help it is possible to determine its resistance. The technique of its calculation depends on the number of signs of marking. If on the code only three figures, then it means that the first two figures, are a certain number by which it is necessary to increase ten in degree which is shown by the third. Example: code 242 means that number 24 needs to be increased by 10². Resistance of such resistor is 2400 Ohms (2.4 kOhm).
4. When marking in four figures from the first three the number is formed, and the fourth shows number 10 degree by which it is necessary to increase this number. Example: code 3681 means what 368 is multiplied on 10^1 and 3680 Ohms (3.6 kOhm) turn out.
5. If the code consists of 2 figures and one letter, use the table of marking of SMD resistors of EIA which can be found in reference books or on the Internet. Example: code 62D, according to the table we find that code 62 corresponds to number 432, and letter D of degree 10³. Resistance of the resistor is equal 432•10³=432000=432 to kOhm.
6. Determination of resistance of the resistor on color strips. On some resistors color tags or continuous rings are put. Find the table of correspondences of flowers to digital values. Each of the front three pages designates number figure. The fourth – degree of number 10 by which it is necessary to increase the number received earlier value. If there is the fifth strip, then it means percent of admission of an error on the resistor.