Different length legs on radial through hole inductor

Thread Starter

SamR

Joined Mar 19, 2019
2,391
Why? It's not to indicate polarity like a LED or electrolytic cap. It's a wound bobbin through hole device, not a tiny surface mount device that may change characteristics depending on mounting orientation.

IMG_0429.JPG
 

BobaMosfet

Joined Jul 1, 2009
1,175
If the lead lengths are uniform across components, it's possible that is just due to the machine they used was set to cut lead lengths as if it was a polarized component. As an inductor, I'd say use a signal generator and see how it behaves one way and then flip it around and see if it's identical the other way. Discrete, low-current, low-voltage signal, in case they've got something in their inside the coil for polarity.
 

Thread Starter

SamR

Joined Mar 19, 2019
2,391
I built a Hartley oscillator with the 2 inductors in series. It does matter. Bent the legs as shown and when they were both pointing in the same direction got a nice clean sine wave, but not when one was turned the opposite direction.

IMG_0431.JPG SDS00008.png
SDS00007.png
 

BobaMosfet

Joined Jul 1, 2009
1,175
To be honest-- if it has a difference based on orientation, and there is NOTHING else in the component except the inductor, the reason you see a difference is because of the lead lengths, and nothing else.

If you can afford it, cut the lead lengths to the same length, and retest.
 

Thread Starter

SamR

Joined Mar 19, 2019
2,391
To be honest-- if it has a difference based on orientation, and there is NOTHING else in the component except the inductor, the reason you see a difference is because of the lead lengths, and nothing else.

If you can afford it, cut the lead lengths to the same length, and retest.
I didn't change the lead lengths, I just bent them like I do with the big electrolytic caps I breadboard with. When I aligned the bent legs it's fine, If not aligned you see what I got. Didn't matter which inductor was changed as long as both pointed the same direction. Not at all what I expected, but I was very curious as to why the legs were like that as I had not seen that before on an inductor. I'll keep em like they are and chalk it down to learned something new.
 

Thread Starter

SamR

Joined Mar 19, 2019
2,391
The “Dot Convention”
I was thinking about electrolytic markings and had already looked again closely at the inductors and these are dot marked. On the outside shrink wrap they are marked with the 3 digit code and a dot beside the code on the short leg side. I also have several other values in radial with equal length legs some completely unmarked and some with just a value code. None of my horizontal axials are marked. Never had a problem before, but this was my first Hartley oscillator with the 2 inductors in series. Unfortunately when I took the picture they are face down.
 
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