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Spockie-Tech
Site Admin
Joined: 31 May 2004
Posts: 3160
Location: Melbourne, Australia
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Looks OK, But its a bit over complicated to my eyes, given that a single 8-pin $4 PicAxe Micro can replace all of the circuitry in that design, and do it better..
The PicAxe can add Hysteresis (dont ask unless you *really* want to know - its complicated, google it if you want to know why its good), and Failsafe - which is essential for a bot. That circuit has neither and is much more complicated to build.
Of course the PicAxe requires that you make(or buy - they're cheap) a very simple 3-wire programming cable to connect to your PC, which may put some people off.. but you can always ask Aaron or myself, or anyone else (Jake ?) to program it for you..
The Basic Stamp is a nice microcontroller, but they are very expensive ($50+ IIRC) for very little extra functionality over a PicAxe (IMO).
And no, I'm not a PicAxe sales agent in disguise, I just happen to think they are the most cost effectinve, easiest-to-use, most powerful little single chip Micro's I've ever seen, and believe me, I've been through plenty..
(68705, Z8, Pic1684, Atmel PowerBoard, Basic Stamps, and thats just some of the micro*controllers*, which are seperate to to Micro*processors*) _________________ Great minds discuss ideas. Average minds discuss events. Small minds discuss people
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Fri Mar 04, 2005 8:50 pm |
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Spockie-Tech
Site Admin
Joined: 31 May 2004
Posts: 3160
Location: Melbourne, Australia
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Sorry, but not really.. I've checked those pages out before.. they are good to illustrate the basic principles of a speed controller, but you'll notice that Bob clearly states that it has never actually been used in combat applications..
5 amps is nowhere near enough to power a combat robot. maybe a tiny hobbyist sized robot experimenting platform, but not a serious fighting machine with drill drives that can suck over 100amps in combination. The transistor (instead of Mosfet) H-Bridge is far too lossy..
No Failsafe - essential for a combat bot
No mixing - Tank steering is possible or you could do it in your radio if its a flash one, but its much easier to do at the controller level.
Requires you to build a Pic Programmer - a much more complicated circuit than the 3-wire picaxe style interface, and you need a basic understanding of compilers, hex files and so on to use it.
Seperate Servo-PWM convertors and H-Bridges with multiple connection points just give you more places to get something wrong or something to fail in combat.
If you're looking for the cheapest possible solution, you are probably best off buying some Electronize's in from the UK. If you're looking to learn how to do it yourself, be prepared for it to cost you about 3x as much and take 10x as long as just buying them would, but you'll learn a lot along the way.. _________________ Great minds discuss ideas. Average minds discuss events. Small minds discuss people
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Mon Mar 07, 2005 12:45 am |
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