You will need
- Active LC meter or multimeter with a function for measuring inductance
Get an LC meter. In most cases, they are similar to conventional multimeters. There are also multimeters with a function for measuring inductance - such a device you will also work. Any of these devices can be purchased in specialized shops selling electronic components.
Power off the fee, which is a coil. If necessary, discharge the capacitors on the Board. Wipaire coil, the inductance of which you want to measure from the circuit Board (if this is not done, the measurement will be made visible error), and then connect to the input sockets of the device (to which it is specified in his instructions). Switch off the device at the exact limit, usually designated as "2 mH". If the inductance of the coil is less than two, MH, it will be defined and shown on the display, after which the measurement can be considered complete. If it is greater than this value, the meter will show overload - in the senior category will appear one and in the other spaces.
If the meter showed overload, switch off the device at the next, coarser limit - "20 mH. Note that the decimal point on the display shifted to change the scale. If the measurement this time is not successful, continue to shift the limits towards more rough as long as the overload disappears. Then read the result. Looking then to the switch, you will know in what units the result is expressed in Henry's or the MH.
Disconnect the coil from the input jacks of the device, and then solder back to Board.
If the instrument shows zero even at the exact limit, the coil either has a very small inductance, or contains the short-circuited coils. If even at the coarsest limit is indicated overload, the coil is either broken or has too much inductance, the measurement of which the device is not designed.
Never connect the LC-meter to the circuit, under voltage.
Some LC-meters have a special knob to adjust. Check the instructions for the instrument, how to use it. Without adjusting the readings will be inaccurate.
Advice 2: How to determine the inductance of the coil
The inductance of the coil can be measured directly or indirectly. In the first case, you will need active or bridge device, and the second will have to use the generator, voltmeter and milliammeter, and then to carry out a series of calculations.
You will need
- - active or bridge meter inductance;
- - generator of sinusoidal voltage;
- - voltmeter and milliammeter AC;
- - frequency;
- - scientific calculator.
To measure the inductance of the active device, connect the coil and then successively selecting the measurement range switch, select such of them to the result was approximately in the middle of the range. Read the result. If the meter has an analog scale, when reading the results, take into account the price of division, and the coefficient shown next to the corresponding switch position.
On the bridge device after each selector turn the knob balancing of the bridge at any of the end positions, and then rotate it all the way in the opposite direction. Find a range in which the handle is possible to balance the bridge. Having achieved the disappearance of the sound in the speaker or headphones or decreasing readings dial indicator to zero, read the indications on the scale of the regulator (but not the gauge). In this case, as in the previous case, consider the division and the factor that should be multiplied by the range statement.
To measure inductance indirectly assemble the measuring circuit. The AC voltmeter switched to the limit at which the upper boundary of the range corresponds to a voltage of several volts, connect the parallel output of the generator. There connect and a frequency counter. Also in parallel, they connect the series circuit consisting of the test inductors as well as milliamperemeter AC. Both devices should show the current, not the amplitude value measured value, and can be calculated for sinusoidal oscillations.
The generator will enable the generation of the voltage sine wave. Ensure that the voltmeter showed about two volts. Increase the frequency until then, until the readings on the milliammeter begins to decrease. Make sure that they reduce to about half the original value. Select frequency limit corresponding to the measured frequency. Read the testimony of all three devices, and then disconnect the generator and disassemble the measuring circuit.
Put readings in SI units. Divide the voltage across the current. Will the inductive reactance of the coil at the frequency at which the measurement was carried out. It will be expressed in ohms.
Calculate the inductance according to the formula: L=X/(2πF), where L is the frequency, G (Henry), X is the inductive reactance in Ohms, F is frequency, Hz. If necessary, move the result of the calculation in derived units (e.g., MH, microgenre).
Do not touch the elements of the measurement circuit when it is energized.