What's the white component? The one besides the green resistor.

It has 5 pins, the pictures are below.

enter image description hereenter image description here

Here is the circuit. enter image description here

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    \$\begingroup\$ You know that image editing software has a feature called "cropping"? \$\endgroup\$
    – PlasmaHH
    Commented Mar 23, 2018 at 12:48
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    \$\begingroup\$ What does this circuit board do? \$\endgroup\$ Commented Mar 23, 2018 at 12:48
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    \$\begingroup\$ Dark, uncropped, slightly out-of-focus photos. You can do better. \$\endgroup\$
    – Bort
    Commented Mar 23, 2018 at 13:39
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    \$\begingroup\$ "The one besides the green resistor" Just FYI, I suspect the green component with colour bands is actually a fixed inductor, not a resistor. This assessment is due to its shape having relatively large bulges near the ends (often seen on fixed inductors) and because it is in series with part of the variable inductor/transformer which is discussed in the answers. To correctly identify the green component, which I know is not the subject of your question, you could desolder one lead and measure either L or R. \$\endgroup\$
    – SamGibson
    Commented Mar 23, 2018 at 13:49
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    \$\begingroup\$ @SamGibson you can clearly see the inductor marking under the component. \$\endgroup\$
    – vidarlo
    Commented Mar 23, 2018 at 19:04

3 Answers 3


Due to small slit on top for a screw driver and wires on the sides, I would guess a variable inductor. (Like a potentiometer, but for inductance instead of resistance).

Example from coilcraft: Example datasheet (see page 4)

Extracted from document: enter image description here


It could be a trimmable transformer. Such things were used often in radios to tune all the circuits to the IF frequency, or whatever. This was a case where the result of 5% components wasn't good enough, before the age of digital trimming.

The coil or transformer had a ferrite slug in the middle that was threaded. Turning the slug would move it up and down relative to the coils. That would change the inductance of individual windings, and the coupling between windings.

Tranformers that size are only for RF signals. It is too small to handle significant power or to work at low frequencies.


The green leaded component is a fixed value inductor (coil / choke) as that is also the schematic symbol for a inductor / coil on the board under neither of it. The white body device is a variable inductor containing a powdered ferrite type tuning slug for minor adjustment of the inductance value and this appears to be a transformer configuration with a fixed primary / secondary and the opposing side is center tapped primary / secondary.


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