Breaking through hole inductors

I've got a string of these JW Miller/ (now Bourns) inductors,

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hanging in a solder chain, (in front of an amp.) I keep breaking the inductors! An open circuit, wiggling the lead around seems to break the inner inductor wire, Is this normal? The current idea is to put a sting into some semi-rigid heat shrink. But I'm thinking it may call for a pcb. (Not all bad, I'd really like to add some taps to the sting.)

George H.

Reply to
George Herold
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I'm not sure it's "normal" but it happens especially if mechanical stresses on the leads are present.

If you are getting the parts with straight leads and bending the leads, you want to make sure that while you are bending that stress is relieved before the body. e.g. hold the lead side towards the body with pliers.

If you are forming a chain supported at the ends.... all ferrite core inductors have a density much higher than a typical resistor say, and this is not a good idea, it's like supporting a dog by it's tail. Some other inductor styles have a kind of mechanical strain relief other than the leads.

These can also be burnt-out-open with overcurrent.

Tim.

Reply to
Tim Shoppa

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Thanks Tim, I don't think it's an over current thing. The inductors broadly 'tune' a wire antenna (low Q), less than 100uA max current. As you say I'm now nervous that even bending the leads to stuff them into a pcb has the potential of breaking the internal wire. I would have thought the mold on the outside would provide more strain relief. Is holding the lead with needle nose pliers next to the body, while bending the lead SOP when stuffing inductors? There's an equivalent API-Delevan part at twice the cost. Worth it I guess if it actually works. :^)

George H.

Reply to
George Herold

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I don't speak for anyone else but i consider pliers or something holding the lead nearer the body than the bend standard for bending the leads of any leaded part, required for axial leaded parts and any more than 3 leaded package. Has it saved me time and pain(?), i say so but that is just anecdotal.

?-)

Reply to
josephkk

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Thanks Joseph, I convinced my boss we need a string of inductors with taps in between. (Not my idea, I stole it from Charles Wenzel

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nics/antennas.html) So a little pcb is in the works, and I've ordered some other inductors... the surface mount ones look more robust.

George H.

Reply to
George Herold

I've used them in the past and never had a problem. Unless they have cheapened the design (which is always possible), the only way to overstress the lead was by either pulling it or bending the lead too close to the body. I used a plastic bending guide that supported the lead where it goes into the body so the guide takes the bending load and not the case.

As I recall, the design was a ferrite bead with the leads insulated and glued into the ends of the bead opening. Magnet wire was soldered onto one lead and then wound over the bead and terminated to the other lead. Completed assembly was then over-molded with Bakelite. (bakelite, yeah, it's been a while...)

Reply to
Oppie

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Thanks Oppie, We ended up using the 'same' inductor from API Delevan. (At ~ twice the cost) I wiggled the lead around on several to the metal fatigue breaking point... breaking the lead where it went into the inductor body. But never did I open circuit the inductor.

George H.

Reply to
George Herold

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