What's the idea of short-legged thruhole parts? - Page 1
Forum section: electronics / beginners

author: lpc32
author_rank: Frequent Contributor
timestamp: October 29, 2014, 05:34:27 pm
content: Like this diode:

author: jeremy
author_rank: Super Contributor
timestamp: October 29, 2014, 05:38:58 pm
content: Did it come on tape? Maybe someone just precut the tape at a store.

author: Simon
author_rank: Unknown
timestamp: October 30, 2014, 12:53:14 pm
content: maybe it's second hand, where did you get it ? I saw some "chopped off" 7805 regs once on ebay that were claimed to be new for a very good price. I contacted ebay and they basically said that they couldn't give a flying fuck.Not all of us do this though just the scumbag minority

author: Richard Crowley
author_rank: Super Contributor
timestamp: October 30, 2014, 12:58:16 pm
content: You example photo appears to show that the leads are different length, as they should be, to differentiate the anode/cathode. So it isn't just a dumb hack-job.Note that if you are hand-assembling thru-hole components and then sending the board through a wave soldering line (etc.) those short leads are much easier to deal with when it comes to soldering and final trimming.

author: Simon
author_rank: Unknown
timestamp: October 30, 2014, 12:59:56 pm
content: If the LED originally had leads that were quite long and it was cut from the board nothing stopping anyone from then cutting one of them shorter to make it look genuine.

author: lpc32
author_rank: Frequent Contributor
timestamp: October 30, 2014, 02:21:09 pm
content: I don't know what exactly the original packaging was (indicated as "bulk" and "carton"), but the size is from the manufacturer. It'sAvago/LiteOn ASDL-5880-C31.So it's for large-scale/automated assembly (why hand assemble, don't machines handle this sort of parts as well?). How come most items seem to come with long legs, or is it that you have both short and long variants depending on some specific item subcode?Quote from: Richard Crowley on October 30, 2014, 12:58:16 pmThough, it appears some original parts do use same-length legs. Maybe then the case shape indicates the directionality?

author: Simon
author_rank: Unknown
timestamp: October 30, 2014, 02:36:50 pm
content: No idea why so short, I guess they just decided to supply them that way. most people would indeed end up cutting them down. The extra wire costs very little so on the whole it's easier to supply longer and let people cut it to length than have them wanting it longer.Yes on diodes and LED's one leg is usually longer than the other to indicate polarity, I think the anode is longer but don't quote me.

author: Codemonkey
author_rank: Regular Contributor
timestamp: October 30, 2014, 02:52:52 pm
content: I imagine the savings on less lead length would add up quite significantly. Assuming a saving of 10mm per leg (being conservative, probably a bit more), with 8000 LED's per box that's 160 metres of material saved! If you're making millions of these a year then its quite a saving. Also shorter leads are likely to be easier to poke into a PCB.

author: Richard Crowley
author_rank: Super Contributor
timestamp: October 30, 2014, 04:01:26 pm
content: I would like to see automatic insertion machines handle even the short version. If someone has an example, please cite it, it would be very interesting. Because the leads are NOT rigid, they will be difficult to accommodate automatic-insertion without a high failure rate. Maybe they have some kind of lead-straightener before they try to insert them?Indeed, both the package shape, AND the lead-length are indicators of polarity. But I have handled LEDs where the little flat on the side of the package was so slight I couldn't feel it or even see it without magnification. The lead length is a much more convenient indicator, IME.