Re: Advice about buying a 7904


Reginald Beardsley
 

Sean,

Thanks.

That fuse looks pretty easy to make with a 3D printer and an electroplater. If someone wants a 3D printer but SWMBO says no, here's a good argument for getting one. "It's a business." Obviously not high volume, but you could easily get away with charging a stiff price relative to material costs. You would not need to sell many fuses to recover the cost of the 3D printer and the gold electroplating setup. You guys no more than I do, but $5 for a replacement fuse which is otherwise pure unobtainium seems pretty fair to me.

It would take a bit of experimentation, but the construction is a piece of fuse wire threaded through the flat part with gold contacts electroplated to a pad, probably conductive paint silkscreened to the base, to form the contact and hold the wire in place. The top part is just to hold it in place.

You'd need a way to impedance match the design so it looked like 50 ohms. An 11801 series with an SD-24 would do that quite nicely.

A cheap work around repair would be to lay a piece of the appropriate fuse wire across the gap and use a $25 el cheapo gold electroplating kit to plate the wire to the board.

Reg

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