Nf-ID: #R:cup.portal.com:64176:trsvax:1195667297:000:4725
Nf-From: trsvax.tandy.com!earl    Aug 18 16:39:00 1992



/* ---------- "Re: Futaba speed control with Airtr" ---------- */
>Ok, I know that Airtronics receiver can be used with a Futaba servo,
>does anyone see any problem using a Futaba Electronic speed control with
>an airtronics reciever?  I really dont want to blow up the speed
>control, but Airtronics want >$100 for thiers and I already have a
>Futaba in an R/C car, soooooo I want to use that.  
Go for it - as was mentioned before, get the speed control wiring set up
first, or the speed control will go the way of the Great Part Bin in the
sky.  ;-)
>I'm going to put it in a Great Planes PT-Electric.  I really dont like
>the cheesy little microswitch pushed by a servo arrangment they want to
>use.
The only problem with using a speed control in lieu of servo/switch, is
that you'll lose some flying power & time from losses generated by the
speed control - I would guess at least 2-300 rpm less and about 5 percent
reduction in run time - especially if your Futaba ESC is one of the older
low frequency switching rate units - but I'd give it a try and see how it
goes, anyway.  (I'm a charter member of Tinkerer's Anonymous.)
  -swb-  (Steve Bixby - sbixby@cup.portal.com)
**************************************************************************

   Using the Futaba speed control should not be a problem at all, but...

   If your speed control has some adjustments, adjust it so that you don't
have a reverse throttle setting. Getting reverse motor in the air can be very
disasterous. The neutral adjustment will usually do this, by setting it so that
the OFF point is at the low throttle stick setting.

   Next do not use the BEC feature on the speed control to power your airplane.
The car speed controls will run the battery all the way down, until everything
goes dead. Regular model aircraft speed controls have a AUTO-CUTOFF feature
added to the BEC function, so that when the battery voltage reaches a minimum
critical voltage level, the speed control will cut off the motor, but still
allow enough power to run the receiver and servos properly. Most RC car speed
controls won't have this feature. In this case you simply use a small, extra
nicad pack for the airborne system. For a PT-20, you can use a 250 mah battery
and it'll work OK. All you have to do is connect only the signal and ground
wires from the speed control to your throttle channel on the receiver. The 
speed control's red power line is left unconnected. You should be able to
pull the power pin out of the connecter with a x-actor knife point, easily
enough, by lifting up on the plastic retainer tab on the connector. Then cover
the exposed pin with some tape to prevent shorts, and your in business.

    Futaba also uses a more "industry standard" connector pin out system for
their radios versus Airtronics.
     Basically:

           FUTABA                  AIRTRONICS


   1   White - Signal        1  RED stripe  - Power
   2   Red   - Power         2  Black       - Ground
   3   Black - Ground        3  Black       - Signal

     But if you carefully remove the little plastic tab on one side of the 
Futaba connector, you can then have the ability to plug the Futaba connector
into the Airtronics receiver. Then all you have to do is carefully pull the two
power pins out of the Futaba connector (power and ground), reverse them and plug
them back in. Then if your always careful, you can use the red wire as your
guide, when your plugging it in, so that you don't get it in backwards.
I suggest that you put a piece of marked tape on the cable, near the connector,
and mark it so that you can tell whether your setup for Futaba or Airtronics
for the pinouts, just in case.
     Of course you can always make up a little short Futaba to Airtronics
adapter cable with a Futaba connector on one end and a Airtronics connector
on the other end. But the servo pigtails, or the servo extension cables are
still expensive.
     The speed control gets its power off of the 6 or 7 cell nicad motor
pack, and the receiver and servos use a regular small 225mah pack for their
power. Just pull the signal pin out of the connector on the speed control and
tape it up so it doesn't short out.

I hope this helps you out.


***********************************************************************


<This information is provided by an individual and is not nor should be
 construed  as  being  provided  by  Radio  Shack or Tandy Corp.  Radio
 Shack/Tandy Corp has no obligation to support the information provided
 in  any way. > 
						
						Earl W. Bollinger
						@ <trsvax!earl>


"You were in the Clone Wars!", said Luke excitedly.
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