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Spockie-Tech
Site Admin
Joined: 31 May 2004
Posts: 3160
Location: Melbourne, Australia
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If you just need drive control, with no weapon channels or low voltage capability, *and* your radio has mixing functions, then Electronize's are about the cheapest reasonable solution I know of.
They achieve this by using relay reversing instead of a Fet H-Bridge, which drastically reduces the complexity and cost of an ESC at the cost of reduced reliability when handling high currents (The relays melt or weld)
I think you can get a pair of Electronize's for about $200Aus (Can you confirm Philip ?).
The next step down in the PicAxe Relay Controller - an *experimental* circuit that does the same thing as servo-switching without the mechanical linkages and problems therein. There are threads on this board with circuit diagrams and code to build your own. They are not commercially available, so you need to be handy with a soldering iron and prototype circuit board assembly if you want to try this route. You also need to run the PRC from a secondary receiver-type battery, as they have proven to be sensitive to the massive voltage spikes that sudden full-power relay switches throw onto the main batteries. Estiamated cost to make your own PRC = ~$50-80 and a heap of time.
Another experimental option is drill-trigger controllers. Only those with the "magic-touch" of making junk somehow hang together in combat have suceeded at this (Jeff and Andrew ). It is possible to hack up the speed control triggers of drills into a functional ESC if you're the sort of person to whom assembling "Heath Robinson" contraptions is a joy.. If you have low patience or machinery tends to go "clunk" instead of "click" for you, then not reccomended.
Beneath this, you are into the land of servo-switches, and other lash-ups (servo controlled wheelchair drives etc), which usually end up causing so much frustration that you will end up buying an ESC sooner or later.
Its the thing that every roboteer squirms and tries to avoid.. Surely there must be some cheaper way of controlling those big motors effectively ?
Unfortunately, The answer is, NO, there isnt a cheaper way. Producing and controlling large amounts of power requires expensive machinery. If there was an easier way that we knew about, trust us, we'd be using it.
If reliability and tinkering-time arent major issues, feel free to tinker around with PRC's, Drill Triggers and Servo Switches.. If you just want it to work reliably and easily, you have to bite the bullet and buy an ESC, its the only way. _________________ Great minds discuss ideas. Average minds discuss events. Small minds discuss people
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Wed Sep 13, 2006 11:12 pm |
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