John Kasunich wrote: > Jon Elson wrote: > >> John Kasunich gives an excellent response, but didn't mention >> connectors. >> > > Actually, I did, in some detail: > Agreed, you definitely did mention at least one, specifically! But, a multi-axis servo control will have multiple connectors, and the cost just adds up. On some of the higer-end boards I make, in the PPMC series, the connectors are over 50% of the total board cost. These are 2-part, screw-terminal connectors, and can run $15 per pair. (On others, some of the special chips are still dominant.) > You provide some good detail though - of the $97 total parts cost, only > $12, or just a hair over one-eighth of the total, is the main "brain". > It seems like nobody ever thinks about the other seven-eighths when > these projects are being discussed. > Absolutely, when you dive into one of these projects, all you think about are the components that actually do the work. And, you never think about the labor or machines to assemble it until you have a blank board in hand. The PC board and the connectors don't do any actual "work", they just make it possible to produce in quantity and hook up easily. > I want to see these projects succeed as much as anyone - but you MUST > focus on the big ticket items. "Servo under $100" needs a clever way to > reduce the "overhead" costs of board, connectors, and packaging, much > more than it needs a suitable packet format. > Yup, I'm going broke trying to compete with Mariss Freimanis of Gecko, who has REAL economy of scale on his side.
If the $100 is for a home-made milled PCB you put together yourself, it is quite possible, but that will take a lot of time to make the board, assemble and debug. Also, the vagaries of switching power designs (not something I have to explain to John, this is for other readers) can have even an experienced designer going in circles for months. Check out the trials of the UHU servo board, which was an open-source hardware project that took several years to get a working unit at the design power level. (The UHU is not open-source software, though, just to be precise.) So, home builders should beware, hooking up a couple FET driver chips and a PIC is not likely to get you a servo running in a weekend. Jon ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
