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Speed controler info
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Spockie-Tech
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Dont worry, 4 x 18v drills at 24v will probably be OK.. Especially with a fan..

12v drills at 24v uses much more current than 18v up to 24v will, so you have a fair bit more safety margin there.

It also depends on how beefy your batteries and associated wiring is as well.. most wiring jobs with a connector or two in them and average batteries will voltage sag a bit under load, which helps reduce the stall-power load somewhat as well..

If you have high-current batteries, thick short wires, and good connectors, then in a stall situation, all the power has to go somewhere, and its either the IBC or the motors that have to burn it all up as heat. neither of them is going to like it..

When I say "stall" however, I mean *sustained* stall.. the IBC will cope with *brief* surges over 100amps if its given a chance to cool off in between.. But if you lock up all 4 drive motors, and keep pushing at full power for 30 seconds, thats asking a lot. 4 x 12v drill motors stalled at 24v have a theoretical (ignoring supply voltage drops etc) current consumption of something like 350+ amps.. keep that up on a 50amp controller and something is going to smoke..

If you do use a tornado-producing fan, make sure you put some form of crud-filter on it (I hear a piece of stretched-over womens stockings work well as a fine mesh), otherwise you will suck every piece of metal filings up and blow it all over your PBC. thats guaranteed to produce a boom..

But KO and Rat are both running 4 x 24v drills.. Rat did blow his IBC once, but thats once out of a lot of fights and demo's over 2 years..
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Post Sat Jul 23, 2005 12:10 am 
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Totaly_Recycled
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I use very small older cpu type fans on all of our ibc heat sinks and have had no trouble i also use airconditioner type filter cloth on the suction side of the fan .I have measured amperage surges of up to 120 +amps per motor while rideing around on t2m so far the only ibc we have damaged was because it got conected up reverse polarity .

Post Sat Jul 23, 2005 6:21 am 
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Rotwang
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It was not a stall that overloaded Rats ibc but shorted motors as when 12 volt motors are run at 24volts until the centrifugal force throws the windings out through the slots and minces them up in the magnets. Sad

I don’t recommend 12v motors on 24v. Rat now uses 18v on 24v Smile

Post Sat Jul 23, 2005 7:04 am 
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dyrodium
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If, (god forbid Sad ) my IBC DOES blow under a stall (or some other reason), how would i go about getting it fixed?
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Post Sat Jul 23, 2005 5:59 pm 
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Spockie-Tech
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You just send it to Jason, who will fix it for a very reasonable fee.. (except not in the next few weeks while hes overseas)

Of course, being open-source, you can fix it yourself if you want since all the circuit diagrams, source code and details are readily available,

But I really dont reccomend it unless you are a *very* skilled solderer experienced at working with tiny surface mount components, *and* very thick copper circuit boards (Which suck heat out of your average soldering iron and make it very tricky to desolder fets and so on).
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Post Sat Jul 23, 2005 11:36 pm 
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timmeh
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quote:
Originally posted by Ali:
Im going to run my rambot with 4 x 18v drills @ 24v using the IBC . Hearing that i could blow the IBC if i stall the motors is a bit of a worry , I have a huge 80mm Vantec tornado fan that im going to put over the IBC's heatsink , would that be OK ?


Having a fan dosent mean it will be ok or not ok it just means you are less likely to overheat the ibc and or do damage to it.


If your worryed do what i did and buy eather some fuses or if your worryed they will blow during a fight and you will be sitting there then try a 50amp breaker from autopro or bersons or maby i think repco might sell them to.

They have saved my ass a few times and for around $12 they are well worth trying allso they are self reset meaning when they cool down in a few seconds they will turn back on so you dont have to manually reset them.
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Post Sun Jul 24, 2005 11:19 am 
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timmeh
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Dose anyone know if the ampflow controllers can have there invert input turned on via rc? it only mentions that it has an invert\emergency stop input?
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Post Mon Jul 25, 2005 3:58 pm 
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timmeh
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Sweet just got my sidewinder controller today and its uber small as glen would put it lol.

It is no kidding the same size as my wallet but about 10mm shorter in length.

havent got around to testing it yet but will put my findings up when i do.
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Post Fri Oct 07, 2005 3:13 pm 
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Glen
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now time for some electronic brainstorming....

having thought about my lego IR controllers that i want to use in woodzilla i think theres a bit of a problem.

basically the output from the controller is from 4 wires (where the two motors used to attach). now what i want to do is have one pair wires set off two relays, one for fowards and one for reverse. problem is because relays arent polarised both will go off at the same time...

what im thinking is some form of diode system so one relay will only activate when the polarity is one way and the other when the polarity is reversed.

im shocking with anything electronic so any advice at all will be dearly appreciated, thank you Smile if its not clear enough ill try and spell out the situation a little better next time lol
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Post Fri Oct 14, 2005 7:26 pm 
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Spockie-Tech
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a diode in series with the relay coil is what you want. face one diode in one direction, the other one in the other direction, and connect both coils to the motor wires..

Now, as long as the output isnt PWM'ed you should have a relative called bob.

If it is PWM'ed (variable speed control on the output ?), then it gets a bit tricker, since you will need to add some capacitance to smooth it off to stop your relays from buzzing.
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Post Fri Oct 14, 2005 8:26 pm 
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Glen
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thanks brett, 'sactly the kind of news i wanted to hear Smile

its only all on and all off control so im sure its not PWM
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Post Fri Oct 14, 2005 8:28 pm 
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Glen
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just to clarify things, re the relay coil wiring, is this how it would be done? excuse the tragedy that is this diagram lol.

http://photobucket.com/albums/v357/Cobrarobotics/Woodzilla/?action=view&current=relay.jpg

would any one possibly be able to provide me with a proper diagram if thats wrong too? many thanks in advance if so Smile

ah and diode values... any particular value i should get or can i just use any.
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Post Wed Oct 26, 2005 9:47 pm 
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Knightrous
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You need to put the diode in parallel, not in series with them.

That is a diagram of how they go.
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Post Wed Oct 26, 2005 11:05 pm 
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Totaly_Recycled
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mm Aron i think Glen wants to switch relays from a toy controler like i did in vertex your diagrme is for a protection diode to stop spikes . Ok Glen just a litle more info is needed does the controler you want to use change the motor direction in each pair of wires ? if so you will need a slightly diferent circute to make the relays switch .From what i imagine you want to switch two seperate pairs of relays with the four origional motor wires .Ive drawn you a diagrme for switching so you get foward and reverse with motor brakeing . If i cant get it on the forum pm me and i will e mail it to you .as ive drawn it up in paint . http://www.robowars.org/forum/album_pic.php?pic_id=1042 ok managed to ghange it to a J peg

Post Thu Oct 27, 2005 12:41 am 
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Knightrous
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http://www.robowars.org/forum/album_pic.php?pic_id=916
Diagram which shows how to do the Servo board ones, basically the same as the toy car boards that Glen is talking about.

The way you did it Andrew was by over volting the toy car board to 10v to drive the relays directly, some transistors make this a lot easier and it can be run at 5v.
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Post Thu Oct 27, 2005 12:51 am 
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