Conference vmszoo::rc

    There was a article on this subject (flaperon mixing ) in RCM
    a couple of months back.. If my memory serves me right, The guy
    who did it can up with a mechanical solution.
    
    I have the Address & phone number for FUTABA US at home. I'll post
    it in note 7. You can always get in touch with them & explain what
    you have in mind. If the request is reasonable, I don't see why
    they  wouldn't want to help 
    
    md
    

    Add too....
    While were on modifying transmitters.... I'd like to switch the
    trottle trim to work on the high end on the same radio.
    
    bob
    

    
    		Just a thought, haven't checked it out, but what about
    	Sam's Photo Facts. You can usually find them at any reasonably
    	large library,(Worcester Main Branch).
    
    				Mike
    

    My experience with radio manufacturers is that they do not make
    it easy for you to do any repair/modification of the radio because
    of liability implications.  However, I do understand that for a
    small (?) fee, Futaba will modify your radio to add the flaperon
    feature.  I do not think they will supply the schematics since that
    would imply that they consent to your modification, regardless of
    what it is.
    
    Ken

Last time I looked inside my Futaba, it used the good ol' NE5044
chip from Signetics.  I think its still in there...

This chip is well documented, but if you send me mail, I'll copy
the pages out of the Signetics manual for your reference. 

Anyway, IF the 5044 chip is used in your Futaba, you can easily
trace out the circuit, since it is fairly standard.  Refer to
Fred Marks' book on Getting the Most Out Of Your Radio Control
System for some applications discussion by an expert.

Fred also shows some mixer circuits in his book.

Also, back issues of RCM (back in the days when it was a REAL
magazine, before '82) contain some scattered information by Jim
Oddino on the 5044 and companion decoder, 5045.   Actually, this
stuff adds little to the Signetics info and Fred's treatment.

I understand what you mean about the rat's nest in there; I am
itching to dig into mine.  It is an early transmitter and I want
to add servo reversing; I agonize about where I'll put the
switches. Also, I will throw out the Futaba transmitter board and
inefficient antenna ( the board is at the bottom of the case; the
antenna runs through the case to connect directly on the board).
I'll replace it with an ACE board, mounted at the top of the
case and a more directly connected antenna.  The board will be
quickly changeable for frequency switching.  Another wish list is
to install single stick on the right hand, and modify the encoder
for 7 channels; only 5 are used now. 

All the above is relatively simple, given a little time and
patience.  

    Yeah, I've got the 5044/45 chip set in my signetics book.  It's
    used in the Airtronics CS7P, but I seem to remember the last time
    I looked in the Futaba FGK it had something different.  I will
    resort to tracing the circuit if absolutely necessary, but agree
    that a call to Futaba is in order.  Sure would be nice to be able
    to make simple changes like these yourself, but you'd also have
    to forget about the warranty.  I'll see what Futaba says.
    
    Regarding the throttle trim, I didn't understand the request.  I
    haven't used the FGK yet, how does the throttle trim work?   On
    the CS7P the trim shifts the throttle over the entire range while
    the "total throw adjustment" changes the range.  Are you saying
    that the trim only affects the idle side of the throttle on the FGK?
    If so, that doesn't seem like it would be so bad as long as you
    still have total throw adjustment.
    						Bill

    
    Re. .5 John,
    		I have a Futaba 5LK which I put servo reversing on by
    use of 4 small PCB mounted DPDT switches to reverse + and - from
    the stick pots. I'm by no means an expert in these matters and my
    original investigation resulted in a servo that I had no alternative
    rotation for.(Bad planning) So I got the soldering iron out 
    ( the warranty had already run out) and reversed +/- on one of the
    stick pots, it worked, with no servo recentering problems. So I fitted 
    a small PCB under the aerial at the top of the transmitter, the four
    switches mounted with switch arms in line with the join in the case
    and with a minimum of effort 4 small slots filed into the case.
    Although, with the transmitter case assembled, the switches are
    visible, they can only be opperated with a small screwdriver.
                                                                
    
         
                                      | |      5LK viewed with back
                                      |A|                removed
                ----------..----..----|e|----..----..-------------
               |       |+-  -++-  -+  |r|  +-  -++-  -+|          |
    	       |       || sw || sw |  |i|  | sw || sw ||          |
               |       |+----++----+  |a|  +----++----+|          |
               |  +........+----------|l|--pcb------+.........+   |
               |  :        :          | | (vero)    :         :   |
                   
    
    		Regards trev

Thanks for that info, Trevor.  Mine is a 5LK also, so your note
is right to the point.  The inside of that case, despite the
simplicity of the radio, is a mess.  I mean, the radio has
nothing in terms of "go fast" features, yet there's scarcely room
for anything else.  You've hit on a great solution.  I was
concerned with all that RF flying around in the box getting into
the servo reversing wiring; apparently there's no problem.  

    John,
    	If we're on the right track there's a few finer points.
    I used Vero board to mount the switches. The final board profile
    was trimmed accurately to fit, with the lower corners cut to fit
    at the top coners of the stick pot moulding ( see diagram) which
    enabled me to fit the assembly without any fixing screws.
    	I also trimmed the leads on the back of the volt meter and drilled
    two clearance holes in the board to ensure there clearance. I also
    put pvc insulation tape on the back (track side) of the board just
    in case of posible shorts.
    
    		+--+-^-++-^-+------+-^-++-^-+--+
    		|  |   ||   | o  o |   ||   |  |
                |  +---++---+      +---++---+  |
                ++                            ++
                 +----------------------------+
     
    As far as RF .... all I can say is that I have no problem with this
    over 2.5 years use, but bear in mind I have no Electronic education
    and could not make any guarantees about your equipment. You'll have
    to verify for yourself.
    				.....Trev

    
    Well, I peeked into the 7FGK and my memory was right, it doesn't
    use the 5044/45 chip set.  It's a custom of their own.  In addition
    there are a couple glue chips, i.e. FET swithes and analog muxes,
    but other than that the whole board is surface mount with most of
    the transistors and discretes on side 2 (which is real hard to get at
    without taking the whole damn thing apart).  Not wanting to
    get carried away with a brand new transmitter, I closed it back
    up and started thinking about ways to do this without modifying
    anything.
    	SO... why not build a mixer that sits between the receiver and
    servos, ala Christie?  Each servo gets a digital pulse every 21.5ms
    (measured in my system), and the width of the pulse corresponds
    to the servo position (0.74ms minimum, 1.84ms maximum pulse width).
    To mix flap and aileron properly involves adding the two channels
    for one of the servos and subtracting them for the other servo.
    	I designed a circuit which does the summing and differencing
    using some FET switches, low power op amps and a couple of CMOS
    logic chips.  Basically it integrates up while the pulses are high,
    then integrates down after the later pulse goes low.  A comparator
    after the integrator generates the new pulse.  It's simple, draws
    very little current and works with supply voltages down to 3 volts
    with the components I picked.  To just do the mixing and generate
    the two new servo signals takes 6 chips pluse a handful of resistors
    and capacitors.  I have breadboarded it for one of the channels and it
    works like a champ!
    	So why not just buy a Christie mixer? (you can get one to do flaperons
    I hear).  For one thing they are too expensive, for another I have
    a few more things in mind.  With fairly simple additions I could
    include the elevator channel in this circuit and do flap -
    elevator coupling (so you don't have to change your elevator trim
    every time you lower or raise the flaps).  This will satisfy my
    original goals from .0, but I've come up with one addition I hadn't
    thought of before - failsafe.  If the rudder and throttle channels
    are also routed through this circuit, loss of transmitter signal
    could be detected and a failsafe mode entered (throttle off, slow
    spiral down).  You might even be able to detect when two transmitters
    are on the same frequency (i.e. getting shot down) and enter failsafe
    then.  That would be better than what usually happens when two are
    on the same frequency (servos go past their normal travel, linkages
    get jammed => demolished airplane).
    	Alright, I'm getting carried away, but it WOULD be nice to see
    how much all of this would cost in dollars, power and weight.  I'm
    already convinced that I can meet my original goals with a very
    lightweight box that sits next to my receiver and easily runs off the
    receiver battery. Plus, I might be able to add failsafe and still keep
    it reasonable.
    	I'll send updates as this progresses, anyone got other ideas?
    
							Bill

Well, I'd sure like to build one!  I'd say that if you achieve
all your design goals, including the failsafe, you've got a nice
commercial item - or at least, a magazine article.

Keep us posted, and let me know if you decide to release the
schematic. 

Anything you want done to a radio can be done...

A member of my club (HCRC) has found someone who will perform any mod
to a radio you can imagine.  He also will sell a kit or tested module
so you can do it yourself (he only charges $20 to do a mod).  He will
also upgrade a radio, freq. change, tune, etc.  He also sels a book
with circuits in it so you can do it all yourself.  He works on any radio
and his prices look reasonable.  If you come up with a modification he
doesn't have already he will design it, bench test the idea, field test
the circuit, and do it to your radio, or you can install it yourself, for
only the cost of parts and shipping, the only catch is you have to agree
to let customers call you for the next 90 days to ask about the mod.
Following are examples of his prices:

Description			Kit	Assembled	Installed

System service						$20.00
New Frequency conversion				$30.00
Basic tuning						$15.00
Basic freq. Conversion					$25.00
Repairs ($20.00 min. pluss parts)
"Hobby Radio" - Volume I		$19.95

Aileron/rudder mixing		$14.95	$19.95		$24.95
Elevator/flap mixing		$14.95	$19.95		$24.95
V-Tail mixer			$17.95	$22.95		$27.95
Elevon mixer			$17.95	$22.95		$27.95

Electronic dual rates		$14.95	$19.95		$24.95
Flight pack voltage monitor	$ 9.95	$14.95		
Range tester			$9.95	$14.95
Battery Cycler			$14.95	$19.95

Transmitter servo reversing	$12.95			$17.95
Electronic servo controller	$17.95	$22.95
Channel expansion Futaba 
  FP-2 series AM RX		$14.95			$19.95
Heathkit RC conversion		$29.95			$39.95

Hobby Radio
3001-A Kavanaugh Road
Wilson, NC 27893
(919) 291-8548

If you would like a copy of the price sheet that goes into the details
of the above modifications send me a note at SPMFG1::SMITHC and I will
mail out a copy (interoffice mail only please).  I have not tried these 
people and cannot vouch for the quality of their work or tell you how 
long it takes for them to do the modifications, following is a quote 
from the price list;

	All work is guaranteed and professionally executed.
	All prices are exclusive of shipping, handling, and
	insurance.  All work is performed with minimal turn-
	around, as I WILL NOT be your stumbling block.  Hobby
	Radio will accept checks (with the normal clearance
	delay), as well as money orders and C.O.D.

	Hobby Radio IS the strong link in your RC system.


Happy flying,

			-Charlie Smith

    So, did anyone ever get schematics?? 
    
    I was talking to a guy recently and it turns out he has a FCC comercial
    license and all the equipment that would be needed to tune radios. 
    He'd like to see a schematic before he goes poking around, but says if
    I can't find one, it will only slow us down a little bit..
    
    Thanks!
    jeff