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Ammo Pack vs Tape & Reel (January 10, 2008)

Whether you're a kit designer, hardware reseller, small-time assembler, or stocking up for the PTH apocalypse, you will, at some point, order more than about 2000 of something. This is the point where you get a magic decision, buy components bulk packed or on a reel. There is, often, another option: the ammo pack. Let's look at how all three stack up.

Two ammo packs are smaller than one reel!2000 bulk packed transistors is smaller still.

We'll use a reel of 2N5087s, boxes of 2N3904s and 2N3906s, and a bag of who-knows-what to illustrate my point. The images above make it plainly clear that two ammo packs are smaller than one reel, and bulk re-packaged transistors are smaller than an ammo pack (but harder to work with). How much smaller? According to Fairchild: a case of 5 reels is 375mm x 267mm x 375mm = ~37.5L, 5 ammo packs are 333mm x 231mm x 183mm = 14L, and 5 bulk boxes are 530mm x 130mm x 83mm = 5.7L. This works out to each reel being about 2.7 times bigger than it's ammo pack equivalent. (If you're curious, you get 2.5 bulk boxes/ammo pack.)

Inside an ammo box, all of the components are neatly stacked while still on split-tape

So the ammo pack is more space efficient then the reel (but less than bulk), unless you're using a pick-and-place machine, the ammo pack is also easier to handle. Being square, it's infinitely easier to stack and store, it can also be stood open-end-up for easier dispensing (for reels, this requires a reel holder).

Some of the contents of an ammo box

Internally, the parts on stored on the same split-tape carrier used in reels, the layers are connected in a serpentine (z shaped) pattern; if you pulled out a whole ammo pack and pulled out a whole reel, you're left with the same contents, except the ammo pack isn't bent and contains a convenient "kink" every 25 pieces. It's a little easier to measure ammo-pack contents as well, when you're down to half the box depth, you have half your components left; when you're down to half the usable reel depth (we don't count the spindle) you've used 65.4% of your reel.

Some of the contents of an ammo box

In general, I just prefer ammo packs to reels, when I get the choice. When I don't get the choice, it's reasonably easy task to unreel a reel, folding it into 25-long segments. (Please pretend these are the transistors from earlier and not LEDs.) These are then perfect for stuffing into an ammo-pack-sized box, like say, an old ammo pack.

After de-reeling, you're left with some components, an empty reel, and some paper ribbon

After you've emptied the reel (I cut it into 25-long segments, but you could fold yours), you're left with a pile of components ready for an ammo-pack (if a little rounded), an empty reel, and a huge length of grade A cat toy.

paper ribbon makes an excellent cat toy!


Posted by spiffed at January 10, 2008 9:29 PM

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