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"Steve Tyng" <SteveT44-at-comcast.net>
RE: newbie [TANKS]
Mon, 4 Apr 2005 07:35:17 -0400
> mabey if i could see some pictures of your guys tank
> you send me some pictures of your tanks inside electrical
> that would help alot.
Tim, here you go. This is
the original wiring setup in tank T005. It is designed to handle much more
current and higher voltages than the RC trucks your used to. The doubled
red and black wires feed current to the two aluminum busbars. Attached to
the busbars are two circuit boards (one for each motor) with four
relays attached (the black boxes). The relays are arranged in what is
called an "H-Bridge" configuration. An H-bridge is a way to reverse
electric polarity to a DC motor so you can reverse it's rotation.
Reversing ESC's you are familiar with also use an H-bridge design but instead of
relays will use a type of transistor called mosfets or just "fets" (a transistor
is an electronic relay with no moving parts). There is a great explanation
of how an h-bridge works here (http://www.rctankcombat.com/articles/speed-control/).
The orange/black and yellow/blue wires attached to the top of the relay boards
feed current to the drive motors. The relay boards ARE NOT attached
directly to the Rx (receiver) but to a control board located in the
Pictured here is the control
board that controls the motor relay boards. The black/red/white wires are
going to the Rx and the cable bundle going into the black connector on the lower
right are heading to the relay boards in the back of the tank. The control
board is the brains of the tank in that it mixes the signals from two receiver
channels to provide you with the forward/reverse and left/right motion you are
In case you don't understand
what channel mixing is all about here's a brief explanation.
Mixing allows you to control the tanks motion from only one stick of the Tx
(transmitter). Remember we are talking about airplane type Tx's with
joysticks instead of the pistol grip style you may be used to.
Because a tank doesn't have any steering wheels it's direction is controlled by
varying the speed and direction of it's tracks. This requires two
channels, two motors and two motor controllers. Imagine you are
pushing one stick of the Tx forward to move your tank forward. But this
one motion is only affecting one channel of your Tx and
normally can only control one function like an ESC in a RC car or the steering
the mixer board does is takes this one signnal and then activates BOTH
motor controllers in the forward direction so your tank moves forward. Now
imagine your moving forward and you want to turn left so your move the joystick
to the left. What the mixer board does is to start to slow or even stop
the left motor (but keeps the right motor going) so that the tank turns to the
left. This is what mixing is all about. Without a mixer circuit you
would be forced to use two sticks on your Tx to control tank movement.
This would not allow you the other stick to control the turret rotation and gun
The wiring and mixer board shown here
were one-off prototypes used only in the T005. It worked very well but is
not exactly what is being used today in the majority of tanks but is close
enough for a general explanation.