Conference vmszoo::rc

>    I have seen elec. speed controls advertised in the model mags ranging
>    in price from $39 to $129. Would an electronic speed control be
>    as useful in an offroad vehicle as a street or track racer? I can
>    appreciate where a paved track car would benefit from precise throttle
>    control, but offroaders seem to be more of a damn the torpedoes
>    full speed ahead approach, especially the 4wd types. I am amazed
>    by my sons Boomerang. Full speed lock to lock turns are handled
>    on just about any surface with no sliding or tipping. Except ice,
>    that really gets hilarious with hard tires on smooth ice.

Yes - but not for the reasons your implying.
Offroad vehicles need electronic speed controls so you don't have so
many failure modes getting the mud, oil, sand, and ice into the
speed control.  Every time we raced in the Salty parking lot the cheap
mechanical speed controls were usually out of business in a couple of
laps.    I got the Futaba MC8 from Toms for about $65.  Cut the Futaba
connector off and put it on my Airtronics radio.  Haven't touched the
speed control since.  P.S.  It has a reverse.

              _!_
Bye        ----O----
Kay R. Fisher / \
 
==============================================================

>    every 15 runs or so, even after it lost a battle with a mud puddle.
>    Something I have seen a couple of times is a balloon over the motor.
>    Aren't you running the risk of overheating the motor?
>    
>    Dan
    
Maybe - I know that they do sell cooling fins for the motors.  But the cool
water in the mud puddles helps a lot. :-).

Seriously - I have ran my Hot Shot under water several times.
On hot summer days I have also melted most of the balloon off the motor.

The car is on my work bench ready to be charged and brought in to work.
Problem is I hardly touch it since I discovered Airplanes.

I'll be painting my Sure Flight Cessna 182 tonight and sanding my
Coverite Black Baron.  Floats and Skis are coming UPS.
Launch that sucker!

              _!_
Bye        ----O----
Kay R. Fisher / \
 
==============================================================

    see note 8.. there's been a fair bit of discussion there
                         

    
    
    Can anybody tell me if Futaba servos/Novak speed controls can be 
    used with KO PROPO EX radios?
    
    I know they are not plug compatible, but is the incompatibility 
    farther than that?
    
    KO sells a FET speed control for their radio and also sells the
    same one with Futaba connectors. This makes me think they are using
    the same signal protocol between receiver/servo that Futaba uses.
                          
    Has anybody tried it?
    

    Dan,
    
    	The purpose of the high-point pot is to set the controller so
    that when the transmitter is set to 'maximum speed', the speed
    controller is all the way on (the LED changes from green to red).
    Basically what you do is set the transmitter high and low end point
    adjustments to maximize the adjustment range, tune the neutral pot
    for no movement, and set the high-point pot so that the LED changes
    from green to red at about 80 percent throttle.
    
    Willie
    

    That's it, I guess you don't want to set it to hit full speed (red
    light on) at 100 percent throttle because as the batteries run down
    and the phase of the moon changes, you still want full throttle.
     Either that or the red light doesn't reliably come on at exactly
    the full throttle point and you want some extra to make up for the
    slop.  That was what the directions said, though...
    
    Willie

    Just bought a Kyosho Pulsar 2000 radio for my Blackfoot,I have been
    looking at various electronic speed controls for this unit.My problrm
    is the different types of connectors they talk about G & J???The
    receiver in this unit has small 3 prong male connectors in it,is
    this a standard of some type (ie Futaba J).Kyosho makes a speed
    controller for this and so does Novak they either have no reverse
    or too expensive,there are several other ones that have reverse
    and the right price but do not specify Kyosho,is my Kyosho one
    of the standard types they always mention in the catalogs.
    Thanx for any help
    Les Borda.
    

    
    HI LES,
    
             THIS IS ANGEL, THERE SHOULD BE AN ADAPTOR FOR THAT
             RADIO TO CONVERTED INTO A FEMALE ADAPTOR. THIS WAY
             YOU ARE ABLE TO BUY A GOOD SPEED CONTROL AT A GOOD
             DECENT PRICE.
    
             YOU COULD ORDER THRU THE MAIL FROM TOWER HOBBIES A
             ARISTO-CRAFT SP2040R WITH REVERSE FOR $29.99 
             THIS SPEED CONTROL WORKS VERY GOOD WITH THE BLACK-
             FOOT. I HAVE ONE MYSELF.
    
                                                  ANGEL
                                              MONSTER TRUCK MASTER
    

    (Though this base note is a bit old, maybe it's time for a revival)
    
    I'm about to buy ESC's for both my son's Raider and my Bullet (`tis
    Christmas time...).  They're both used for racing, on-road (carpet)
    in the winter, off-road (dirt) in the summer.  We want proportional
    forward and brake, no reverse.  Mine has got to be very light weight
    (Traxxas should have used the name Piglet, not Bullet, for the stock
    version of this car.  It's rugged, but HEAVY!).  The price should
    not exceed $80 (street, not list).
    
    I'm impressed with all I've read and heard about Novak's T4.  I'm
    also somewhat impressed with Tekin's 300, but I'd like to hear
    more about it.  I'm investigating all the normal channels (mag's,
    shops, users) and hoped that some RC Noters might be able to pass
    on some first, second or even third hand stories about both Novak's
    T4 and Tekin's 300.
    
    Experiences with other ESC's are, of course, also welcome!
    
    Thanks for any info you can share,
    
    Greg
    
    P.S.  I'll post a full report on how whatever we buy works out at the
          track right after the holidays.

    My son uses a T4 on his stock class RC10.  Except for losing the
    little dust plugs over the adjustments, it has been very dependable
    and competitive.
    
    We had a bit of difficulty with the receiver when we first installed
    the Novak into the car with a Futaba BEC receiver.  The problem 
    was not interference.  When the throttle was opened up with a 
    partially discharged battery the receiver would either shut down 
    or would change the width of the pulse fed to the steering or throttle 
    servo.  We chose to solve this by powering the Futaba receiver from
    a LM7805 instead of the internal voltage regulator provided with the 
    Futaba receiver (replacing the BEC). Novak also sells what they call a
    stutter stopper, which is just a 2.2 farad capacitor, which acts to
    stabilize the voltage seen by the receiver and servos which are
    connected as BEC a system. They also recommend their receiver with
    their speed controller (naturally) as they have already solved
    stuttering problems.
    
    Walt 

    I haven't had any problems with the T4 in my JR-X2.  It works just
    fine and doesn't even get warm pushing my 11 turn.
    Fred

    re. .10
    
    Now the light comes on (thanks Walt)!
    
    I have seen these "stutter stoppers" and filed the thought away as
    something else to learn about.
    
    The radios we'll most likely be hooking up to are a Kyosho Pulsar 2000
    and a JR Alpina Beat 2.  Both have been stable so far (not subject to
    glitching).  This is a new angle though, as quickly opening the "spigot"
    on an ESC should certainly let that power flow!
    
    Time to find out what a "stutter stopper" will do to the wallet!
    
    Thanks for the info guys.
    
    Greg

    
    Well, since it's begun to look like there aren't any Tekin ESC
    stories out there, I've taken matters into my own hands...
    
    I bought a Tekin 300.  Two things led to this purchase: a good deal ($)
    and the need to pinch every fraction of an ounce!  The Traxxas "Piglet"
    is going on a diet.
    
    Won't be able to say more until after Christmas, as this is my present
    (i.e. I picked what the family will give me, so they'll now wrap it
    and hide it from me `til Christmas).
    
    Now watch the tales of smoking and burning Tekin's begin to pour
    in to this note!		>;v)
    
    Hopefully I won't be the one recording them!!!!
    
    Greg

    I have a Novak T4 that I use with a Twister Hurricane and Airtronics
    radio in my Turbo Optima.  I have had no problems at all with this
    setup.
    
    I also have a Futaba MC-112b with a Trinity Speedworks Blueprint and
    Futaba Magnum radio in a Big Brute.  I've found this setupt a little
    too sensative to setup quickly.  The brake/full speed adjust points on
    the speed control are not easily adjusted to get the desired control
    on the trigger for reverse/brake/full speed.  I don't think I'll ever
    buy a controller with reverse again.
    

    I'm going to "scope-out" two ESC's: My Tekin 300 and my son's Kyosho
    SC500.  By "scope-out" I literally mean hang `em off an oscilloscope
    and see that they're adjusted properly.  The reason: I suspect that
    the SC500 isn't turning completely on, and I'm not happy with the
    little LED as a tuning indicator.  BUT...I have some questions:
    
    	- What sort of trace should I expect to see?
    
    	- Will I need a load on the outputs?
    
    I'll be using my bench power supply, not batteries, to drive things.
    What I plan to do is monitor the input and output on the scope while
    I tweak the ESC.  With a little luck I'll get input = output at full
    throttle (though I know there'll be a little loss), a true neutral
    spot and brakes.
    
    Anyone do this before?  Sanity checks would be appreciated!
    
    Greg
    

    re 98.15
    
    Greg,
    
    I havn't tried the scope method of measuring ESC performance, but
    doubt that it would be too succesful for various reasons to detailed
    to go into now.
    
    A commonly used method is with an ordinary DVM. I use a $35 3.5
    digit model. An analog meter would probably work too.
    Hook everything up in the car as normal, with a fully charged battery.
    Look across the ESC on the neg. line with the meter so that you
    can monitor the voltage drop through the ESC. With the throttle
    closed you will read full motor battery voltage. As the throttle
    is opened the voltage will drop. At wide open throttle it will be
    at some minimum value, mine are typically .02 volts. Now tweak the
    pot on the ESC and observe that the voltage reading and motor speed
    varies as the pot is turned back and forth. Turn the pot until you
    get the minimum voltage reading. You may have a small amount of
    pot travel left at this point. This is normal. Don't bother to tweak
    the pot to the limit of it's travel. You'll have max current when
    you have minimum voltage on the meter. 
    
    You'll probably need some helpers to hold the leads, hold the wheels
    clear, etc. but thats all there is to it.
    
    Terry
    

I finally got around to actually measuring the current that the Astro Cobalt
05 draws in my Challenger. I've always been a bit uneasy because of 2 things:
the speed controller (it's a Graupner Power Switch 20) is rated at 20A, and
I have a 30A fuse in series with the battery (7 cell). 

I used a digital clamp-on current meter from the lab, which unfortunately is
designed to measure BIG currents, like 400 to 800 amps. So I don't know how
accurate it is in the low current range. I also noticed that like most digital
meters, it HATED to be anywhere near a 72MHz transmitter.

The results: when first turned on with a fresh battery, the meter jumped to 
around 30A, then backed down to about 25A within 5 seconds. It held at 25A
or so for 10 more seconds at which point I stopped the test. By the way, it's
a geared 05 spinning a Master Airscrew 12x8 folding prop.

Conclusions: 

1. Even though the ESC is rated at 20A, I know it uses a simple relay
and I think it can handle the 25% extra current. (Translation: I don't feel
like investing in a more expensive ESC)

2. I got REAL nervous about having the fuse right at the battery. If the fuse
blows, I lose control of the plane since I'm using the battery eliminator
feature of the ESC. So I moved the fuse to between the motor and the ESC. Now
if it opens, I still have power to the radio. Of course, I could have bought a
bigger fuse, but I feel more comfortable with this solution.

3. I believe the current should drop once the plane is in the air and the prop
unloads, but I don't know how much (anybody got any estimates?). I also plan
to experiment with a smaller prop to see how it changes the current draw. As
well as the run time.


Dave

    re .17
    
    Dave, your numbers confirm what I've experienced, running a ferrite
    125W motor, direct drive with a 7X3 and 8.5X4 prop, and also geared
    3:1 with a 12X7.
    
    A 20A fuse would always blow after 5 secs. of full power in static
    operation, but a 30A never did, so I've always used the 30, and
    never tried the 20A in the air. Current draw in the air would depend
    a lot on flight attitude, but in level flight I'd guess that the
    draw would be at least 5A less, with a full charge.
    
    When I changed from a 7X3 to a 8.5X4 prop on my 41oz. Thermic Traveler
    I noticed a slight reduction in run time at useable power levels,
    not enough to even bother trying to measure accurately, but there
    was a good jump in climb performance. Changing prop sizes with a
    geared prop is less noticeable unless you make a much bigger jump.
    I can't notice any worthwhile difference between a 12X7 and a
    14X7.
    
    BECs scare me, so I don't use them. I use a separate rcvr pack made
    from some little 180ma Panasonic cells. I think  they're AAA size
    and stay "in the green" for 25 minutes @ 200ma load on my ESV. I
    swap packs after 20-30 minutes flight time. They weigh about 27
    grams per pack.
    
    Terry
    

    I'm looking for some advice from the electric A/C crowd....I currently
    have a Futaba attack radio with the built-in speed controller.  Now
    I'd like to buy a seperate Electronic speed controller to go with a 
    new radio(make and model of the new radio are undetermined but that's
    another note).
    	What experience(good or bad) have you had with an ESC for aircraft
    use?  Any recommendations about what to buy or avoid?   I know there's
    quite a few electric modelers out there....let me know you thoughts.
    
    
    							regards
    
    							Bob
    	 

    I've had good luck with a Novak. Readily available in several models
    with choice of connectors. Prices no worse than most. Have'nt
    tried one with more than 7 cells. For larger cell counts..>8 to
    15, I'd go with Aero-Zeta, if you can find one.
    
    Have also had good luck with a Tien-Kee, Taiwanese rip-off of a
    Novak. Hobby Lobby used to sell them for <$60. Have never had any
    trouble with any of my controllers. Use Sermos connectors and a
    good airflow and you should be happy.
    
    Terry
    

    It's worth the effort of finding a High Frame Rate controller.  Many
    controllers use the Pulse decoded by the receiver to drive their FETs.
    The rate of this pulse is quite low, the result being extra heat, and a
    corresponding loss of efficiency.  High Frame Rate controllers run at or
    above 10KHz, making more effective use of your available power.

    Unfortunately, I can't remember which makes are HFR.  Most of the ones I
    own are Low Frame Rate.

    I currently own a Futaba MC112 (LFR), an AstroFlight MumbleMumble (LFR)
    (notable for it's ability to support up to 20 or so volts, and it's low
    cost of only around $60),  and A Novak NESC-4 (old and tired).  I'm
    about ready to upgrade, though.  This months electric column in RCM
    mentioned a speed control worth consideration.

    The JOMAR series of ESCs are high rate, and are fequently applauded by
    Bob Kopski and many of the experienced electric flyers.  I believe they 
    run at between 3Khz and 5Khz, but my scope isn't good enough to tell.  
    I have both an SC5 built by JOMAR and an SC4 which I assembled myself.  
    The SC5 is smaller, lighter and will run on less than six cells, but it 
    lacks the optical isolator and current handling capacity of the SC4, 
    which will happily handle six to twenty eight cells.  He also has a new 
    one for REALLY big installations, but I don't remember the model number.
    
    Both have been replaced by surface mount versions (SM4,SM5) but they
    seem to be a little pricey and in short supply.  A friend gave up 
    waiting for one and bought a Sommerhauer (Sp?).
    
    If you're handy with a soldering iron, you can order just the PC board
    for $5.00 from Joe Utazi (JOMAR).  Completed units are available(?) from
    a variety of places like Tower, SR Batteries, and of course JOMAR.
    
    Another point worth mentioning, is that frame rate doesn't matter
    unless you're running at partial throttle.  When power is fully on or
    off, the rate is always zero.  In that case, the weight, on-resistance,
    and current handling capabilities are your only concerns.  A glider
    which only uses the motor to climb would be one example.  I would think
    that most of the recently released ESCs are comparable in efficiency,
    but don't know that for a fact.  In any case you'll lose more power in
    the fuse than in the ESC.

I have a Futaba MC12B(AM) speed controller and was wondering if the only
difference between it and the MC112B(FM) is the connector. The reason I'd like
to know is that I'll be using an FM radio(Aristo-Craft 720) in my electric plane
(DSC Fly Baby) and the receiver has Futaba J connectors. Any help would be
greatly appreciated.

Thanks,

-Lamar

> <<< Note 98.23 by ESCROW::PHILLIPS "DECtp Engineering TAY1-2  DTN 227-4314" >>>
>     -< What's the difference between  MC12B and MC112B speed controller >-
>
>I have a Futaba MC12B(AM) speed controller and was wondering if the only
>difference between it and the MC112B(FM) is the connector. The reason I'd like
>to know is that I'll be using an FM radio(Aristo-Craft 720) in my electric plane
>(DSC Fly Baby) and the receiver has Futaba J connectors. Any help would be
>greatly appreciated.
>
>Thanks,
>
>-Lamar

First let me admit that I am not familiar with a MC12B speed controller.
But - all these speed controllers just plug into standard servo plugs
in the receiver and get and use the external battery and controller power
to the motor thru the speed controller proper.

Soooooo - you can cut off the connector to the speed controller and
solder on a connector to fit any other radio (being careful of polarity)
and it should work.  I personally have had a Futaba speed controller (although
a different (older) number than the MC12) and cut off the Futaba servo connector
and soldered an Airtronics connector on.  Worked fine.  Also I do the same
things for servos and all servos (three wire types) work fine with all radios
(three wire types - which all modern radios are).

There are several notes in this file dealing with servo wire pin layouts.
Check 11.1 to find them.

Bye          --+--
Kay R. Fisher  |
---------------O---------------
################################################################################

>          <<< Note 98.24 by KAY::FISHER "Stop and smell the balsa." >>>
>                     -< Speed controls are just servos... >-

Warning - if your speed control is also acting as a battery eliminator
then you have to be sure that the receivers run off the same voltage.
Most receivers are running off 4 cell packs (4.8 volts) but - NOT ALL.

Bye          --+--
Kay R. Fisher  |
---------------O---------------
################################################################################

RE: .24 & .25  by KAY::FISHER

Kay,

Thanks for the information. I had done some looking into other notes, but maybe
not enough. I had a feeling it was only the connector that was the difference,
but wanted to check with the experts to be sure. I'll look under the RADIO_SERVO
keyword to see if I can find info about the pin outs. Also, I'm not using a
BEC setup(the speed controller doesn't have this feature.)

Thanks again,

-Lamar

    Re: .23, Lamar,
    
    I know nothing of ESC's but, if Futaba applies the same numbering
    convention to these as they do their servos, then the only difference
    between an S12B and an S112B would be that the 112B has the "J"-series
    (or FM) connector and the 12B has the older style AM connector.
    
    Futaba does the same thing with their servos, e.g. S48 vs S148; again,
    the 148 has the J-FM connector and the 48 has the AM connector.  This
    convention holds true for all Futaba servos since the advent of the "J"
    series radio ~11-12 years ago.  I've never encountered any problem
    using a servo on which I've changed connectors from AM to J-FM and I
    strongly suspect, as Kay has verified, the same would hold true with
    the ESC.
						 __
				|      |        / |\	   	       
      	         \|/		|______|__(o/--/  | \	   	       
      | |        00	       <|  ~~~  ____ 04 ---- | --------------------
    |_|_|        (O>o		|\)____/___|\_____|_/	   Adios amigos, Al
      |     \__(O_\_	        |	  |___/	 o	   (The Desert Rat)

    
    	Has anyone used the programmable ZETA ESC's or maybe have a 
    	copy of a manual on how to program these things. I just picked
    	up a couple of ZETA's used and did not recieve any manuals so
    	I don't know how to use the little programming boxes that came
    	with the ESC's. Any help will be greatly appreciated.
    
    	Thanks,
    
    			Mike