Graham,
Here's the parts cost for the power section of the G320: 2 IR2104S half-bridge driver $0.81 [EMAIL PROTECTED] 4 IRF540 MOSFETs $0.46 [EMAIL PROTECTED] 1 0.01 Ohm 3W non-inductive resistor $0.31 1 100nF/100V ceramic monolithic cap $0.27 1 100uF/100V aluminum 'lytic cap $0.38 6 0805 chip resistors $0.002 [EMAIL PROTECTED] 2 SOT-23 diodes $0.05 [EMAIL PROTECTED] 2 1206 chip caps $0.06 [EMAIL PROTECTED] 1 0805 chip cap $0.04 Total power section parts cost: $4.69 Total power section assembly cost: $2.81 That gets you a 20A, 80VDC rated power output. A power section that actually comes apart at 33A and 118VDC. The G320 sells for $114. With with our exorbitant profit margin, (3X parts and assembly cost) a zero amp, zero volt output G320 would still cost $91.53. At that price, it couldn't turn the head of a flea (no power section). My point is the majority cost of the drive is not in the power section. It is in everything else that is required to make a drive go; pcb, low-level circuitry, connectors, trimpots, optos, enclosure, etc. Also include phone support, repair and replacement. Not included is development and design maintenance. The design time and effort is a killer. I started a design of a brand new drive last December 15. I have spent some part of nearly every working since then. I have an engineering project book nearly as thick as a Mitchner novel. The drive is just coming to life and if I'm lucky (no setbacks), it may be marketable by the very end of this year. The engineering diaries on the G201/210s and the G320/340s are far fatter. Good and "on the cheap" is the holy grail and I see that as my perpetual goal. It can also be an oxymoron if you are not very careful. By that I mean it's a fine balance between designing something that costs too much or designing something that's too fragile to use. For me "cheap" means a drive shouldn't cost more than the motor it drives and "good" means the drive gets the best out of the motor it drives. If I satisfy both requirements I feel I have done well. My satisfaction as a designer is to conjure up a design that balances without tipping in either direction. Mariss --- In [EMAIL PROTECTED], "Graham Stabler" <[EMAIL PROTECTED]> wrote: > > > As I understand a Gecko 320 would probably work, but that is over > > $100 each. I hope to build my entire machine for under $100. > > I realize it does not fit with the cheap approach although the > reason I ask is that the inductance of the motors can make a > difference to the control I was once told. Also anyone who already > has a set of geckos would find it quite a cheap way to build such a > machine. I am such a person. > > Here is the link to the microchip app note: > > http://ww1.microchip.com/downloads/en/AppNotes/00532c.pdf > > It would be great if this code could be modified to produce a > general purpose step/direction controller for small servo control on > the cheap. > > Graham Addresses: FAQ: http://www.ktmarketing.com/faq.html FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/ Post Messages: [EMAIL PROTECTED] Subscribe: [EMAIL PROTECTED] Unsubscribe: [EMAIL PROTECTED] List owner: [EMAIL PROTECTED], [EMAIL PROTECTED], [EMAIL PROTECTED] Moderator: [EMAIL PROTECTED] [EMAIL PROTECTED] [EMAIL PROTECTED] [Moderators] URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO OFF Topic POSTS: General Machining If you wish to post on unlimited OT subjects goto: aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if you have trouble. http://www.metalworking.com/news_servers.html http://groups.yahoo.com/group/jobshophomeshop I consider this to be a sister site to the CCED group, as many of the same members are there, for OT subjects, that are not allowed on the CCED list. NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING THEM. DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........ bill List Mom List Owner Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
