Subject:
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Re: Make Your Own HiTechnic Style Radio Control?
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Newsgroups:
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lugnet.technic
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Date:
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Thu, 8 May 2003 16:19:11 GMT
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Viewed:
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1889 times
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In lugnet.technic, Tobbe Arnesson writes:
> > I have posted the web page that explains how Radio Control Systems work and • how
> > to modify a radio control servo to drive Lego motors.
> >
> > The web page is: http://users.adelphia.net/~istafford/lego-radiocontrol.html
>
> There should be a group for this sort of things, alas there is not.
>
> How does the motor behave? I'm no electronics expert but I think I followed
> your description.
>
> The best way for a system like this would be:
>
> 1) The stick on the transmitter is in it's center position = the LEGO motor is
> shut off.
>
> 2) The stick is in a extreme postiion = the LEGO motor reveives full power
>
> 3) The stick is in the other extreme = the LEGO motor has full power in the
> other polarity
>
> 4) The stick is between full and center = the LEGO motor has half power.
>
> Since the limitations on voltage with your solution I don't think it's an • ideal
> one, even if the above is true. I would like some custom made circutry to
> connect between the receiver and the motors, this should interpret the signals
> and vary the power on the LEGO connectors. Of course it should use an external
> LEGO 9V supply (or 18V for the dare devils).
>
> This way, no servos or their internals would have to be used. Just plug in the
> custom board to the receiver (preferably five channels), hook up the power
> supply and connect the motors.
>
> Perhaps the custom board could have a power out for the receiver to avoid • using
> an additional battery pack for that.
>
> But until this exists, I think your solutions is the best one.
>
> Best regards,
> /Tobbe
> http://www.lotek.nu
> (remove SPAM when e-mailing)
Tobbe,
Your comments are right on. The way the servo card controls the Lego motor is
as you described except that the circuit has so much "gain" that the motor is
almost full ON when the stick is on either side of the mid point - very little
slowing.
There are circuits that do exactly as you suggest. They are Radio Control
Model Car 'Electronic Speed Controls'(ESC). Some are designed for forward and
reverse operation. That is what is needed to get the linear operation
mentioned in your point 4. The voltage limitation is resolved because most
ESCs can take up to 8 cells (9.8 volts) and they do provide the correct voltage
for the receiver. The cost of ESCs have dropped and used ones are probably
available. I have not tried one but I plan to. I'll let you know how they
work out.
An example of the kind of ESC that I think will work is sold by Hobby People.
It is their Mtroniks Eco 20. See it at:
http://hobbypeople.net/gallery/159120.asp
Irv Stafford (So. Calif AFOL)
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Message has 2 Replies:
 | | Re: Make Your Own HiTechnic Style Radio Control?
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| (...) DOH! Now I'm really embaressed :) Why didn't I think of that? It's so obviuos! And I've always been the black sheap of the family, prefering RC cars before planes (never owned a electric one though)... *sigh* (...) I have to research this (...) (22 years ago, 9-May-03, to lugnet.technic)
| | | Re: Make Your Own HiTechnic Style Radio Control?
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| i'm not an RC expert nor do i have much electronics experience, but has anyone ever thought about using the circuit from a zipzaps type micro rc car to make an RC lego brick? according to this page: (URL) you can safely hook up 4 AA batteries to the (...) (22 years ago, 13-May-03, to lugnet.technic)
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Message is in Reply To:
| | Re: Make Your Own HiTechnic Style Radio Control?
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| (...) How does the motor behave? I'm no electronics expert but I think I followed your description. The best way for a system like this would be: 1) The stick on the transmitter is in it's center position = the LEGO motor is shut off. 2) The stick (...) (22 years ago, 8-May-03, to lugnet.technic)
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