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Wiper motors???
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leo-rcc



Joined: 04 Aug 2006
Posts: 231
Location: Hoogvliet, Netherlands


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You might also want to check out the Robbe navy 540R. They are single motor, so you would need two of them, but they are more than capable of powering your wheelchair motors.

High-performance speed controller with forward / stop / reverse functions, for 600...700 motors, or multi-motor models with 500...700 motors; also for high-performance power systems based on Pro, Sports and Ultra motors. broad operating voltage range of 6...28 V (6...24 V lead-acid batteries). With extreme heat-sink to cope with a continuous load current of 40 Amps, as required for high-capacity batteries. Sealed with acrylic lacquer to protect from splash damage.
Specification:

Operating voltage: 6 - 24V Volts

Momentary: 70.00 A
They sell them here for €89 euro's.

http://www.modellhobby-shop.de/modellhobby/index.php?show=details&product_id=712&ktg=102

Post Wed Sep 13, 2006 9:58 pm 
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Glen
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Joined: 16 Jun 2004
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for 89 euros it would cost the same to just get an IBC, and youd get the mixing and weapons channels with it.

im sure one would take a pair of wheelchairs.
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Post Wed Sep 13, 2006 10:03 pm 
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Spockie-Tech
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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 Wink ). 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. Wink

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. Sad
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Post Wed Sep 13, 2006 11:12 pm 
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WiperMotor



Joined: 04 Sep 2006
Posts: 301
Location: SA,Australia


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Ahh Thanks for such a detailed reply.

I was sorta looking down the servo and micro switches road but it has made it so much harder for me because I just spent my last $70 bucks on these wheel chair motor and wheels. My main problem is my radio is a [ I --] type radio (if that makes it any clearer) so I was thinking of trying out a system with a few micro switches but I can't figure out wether it will work because I don't have a good circuit building program atm. Failing this I would like to see if I could find a proper wheel chair controller to try out but Again I am not sure how well this will work out because from what I have heard They aren’t much good for this sort of work Sad .
But I'll keep looking and see what I can find on the web and around town Wink

thanks
Simon

Post Wed Sep 13, 2006 11:29 pm 
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leo-rcc



Joined: 04 Aug 2006
Posts: 231
Location: Hoogvliet, Netherlands


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quote:
Originally posted by Glen:
for 89 euros it would cost the same to just get an IBC


if its 300 US dollar no, Aus dollar yes.

Post Wed Sep 13, 2006 11:42 pm 
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Knightrous
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Joined: 15 Jun 2004
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Location: NSW


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Sounds like you have a standard 2 channel radio there Simon. left stick is up/down for throttle, right stick is left/right for steering.

You can easily use this radio with some micro switches to drive your motors. All you need is 4 SPDT micro switches and a pair of servos Wink Wiring up the micro switches is real easy, takes about 10mins with a soldering iron Smile
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Post Thu Sep 14, 2006 8:41 am 
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WiperMotor



Joined: 04 Sep 2006
Posts: 301
Location: SA,Australia


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oh ok,Well I can use a solering iron and what not but I was thinking of having micro switches but I am still looking at a few options.They are a bit to hard to explane with out a diagram so I might try to post some pictures later

Post Thu Sep 14, 2006 8:54 am 
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Knightrous
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Joined: 15 Jun 2004
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Location: NSW


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If you want a diagram on how to wire the micro switches up to suit your radio, I can help you with that Smile You might just have to wait till I get home from work Laughing

(Work, woo, meeting at the RSL today!)
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Post Thu Sep 14, 2006 8:59 am 
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WiperMotor



Joined: 04 Sep 2006
Posts: 301
Location: SA,Australia


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oh ok cool,thanks for that

Post Thu Sep 14, 2006 9:05 am 
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Philip
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Joined: 18 Jun 2004
Posts: 3842
Location: Queensland near Brisbane


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quote:
Originally posted by Spockie-Tech:
I think you can get a pair of Electronize's for about $200Aus (Can you confirm Philip ?).(
Brett is correct. The 30 A Electronize controllers are about AU$200 including postage to Australia for the pair. This will vary according to the exchange rate on the day of purchase. http://www.electronize.co.uk/

There are cheaper controllers as well from Electronize. I would avoid the ones without microprocessors as they don't have failsafes.

The 30 A controllers I have been using have never become warmer than ambient temperature. I have had motors too hot to hold and even had a dead short on one side.

You can choose the external relay option if you want to slam your bot from full speed forwards to full speed reverse at currents substantially over 30 A. As Brett said, the speedos standard relays are only rated to switch up to 30 A. I have not done this.
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Post Thu Sep 14, 2006 5:57 pm 
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WiperMotor



Joined: 04 Sep 2006
Posts: 301
Location: SA,Australia


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Well
I think I might use micro switches for now and then at Xmas I might try to con mum into getting me a pair of them Very Happy

But those speed controllers look very nice Cool

Post Thu Sep 14, 2006 6:12 pm 
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prong
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Joined: 19 Jun 2004
Posts: 839


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I use very cheap and simple toggle switches driven from the servos, these switches then drive 60amp car relays.

The switches were a few dollars and the relays were free from a wrecker.
Easy to wire up and can handle plenty of amperage.

I run 4 12v drills on 14.4v through them with no issues. They are also happy to go from reverse to forwards as quickly as possible over and over.
I also melted all the wiring in the robot with too much current draw with a mostly dead gearbox, the relays handled it fine.

The downside is you only get on or off control. Personally I dont think that is much of a downside. It is harder to control, but you get used to it very quickly and I think with a bit of practice you can drive as well as the bots with speedcontrol.

With servo swithcing I recommend tank control. This lets you very quickly and easily control each side. After a while you find yourself pulsing your finger, giving rudimentary speed control anyway.

While a speed controller is always a nice thing to have, I am not convinced I will ever buy one!

Servo switching is actually pretty easy to build when you use toggle switches to drive relays and seems very robust and reliable. You can also fit it into a similar sized space to most speed controllers.

Also in all the events I have been to I have seen people have WAY more problems with speed controllers than servo switiching. Those controllers love to let out the magic smoke! If you break your switch controller, a few dollars later you build a new and better model.

The main point is the price! a few dollars compared to $200 plus!
All up I have spent about $100 on robots, and had heaps of fun. You dont have to spend lots to have fun or be competitive!

I spent more travlling to the last robot wars event than I have spent on robots all up Laughing

Post Thu Sep 14, 2006 9:16 pm 
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WiperMotor



Joined: 04 Sep 2006
Posts: 301
Location: SA,Australia


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Thanks for that detailed reply Smile

I just found out both of my servos are stuffed and my crystals are missing Mad Crying or Very sad Mad Crying or Very sad

But yeah I have a servo switching setup on the drawing board Wink

Another Question,Is there some whay I can only have one servo able to move at a time? because the speed controller I am building if the other servo is in the wrong spot it will short out Shocked

EDIT: would you have a diagram of how this works? ,I understand most of it bout I'm just having a bit of trouble figuring it all out Shocked

Post Thu Sep 14, 2006 9:25 pm 
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prong
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Joined: 19 Jun 2004
Posts: 839


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Short answer - If set up right there is no way for them to short out.

Long Answer -

The setup I use has 2 servos, 2 switches and 4 relays.
Each servo controls one side of the drive forward and reverse (up and down on the stick)

This means you have tank control, ie, one stick on each side controls one side of the robot, like two control sticks in a Tank.

In this setup each servo and associated switches and relays are independant to each other, so yes you can have both servos moving at the same time and there is no possible way for it to short out.

I do not have time tonight to draw up a circuit diagram for it, but i will try and do so as soon as I can for you.

Keep in mind this system uses both control sticks on the transmitter. Each side independantly controls a side of the robot (tank control)

IIRC it is possible to build a servo switch setup that does mixing (controls the robot from one stick) but it is a lot more complex.

Post Thu Sep 14, 2006 10:09 pm 
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WiperMotor



Joined: 04 Sep 2006
Posts: 301
Location: SA,Australia


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Yeah Thanks for that prong
I'm not in any rush for it just yet because I'm going to be a pedal Prix over the weekend YAHOO Razz

but I was looking to mix it on one stick sorta thing

Catch ya all monday Smile

Post Thu Sep 14, 2006 10:20 pm 
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