Servo tester?

[jrb]

Anybody out there?

Can anybody tell that a new thread has been opened?

Has anybody tried a standard ESC and the guts of a servo tester?

[steve lewin]

Yes one or two of us are still here.

But it's a pain going down a level to see if anything new has arrived (even sillier since C/L would only take up the same screen space on the main screen). But everybody and his dog used it as an argument for their own favourite forums. "If C/L can have a forum when they only get 1 post a month why can't I have a forum for (insert subject of interest) ?" I think Jim just got fed up with aggro after a while and demoted us.

To the subject :

A servo tester and standard ESC work very well and it's really easy to set up. I've tried it 2 ways.

1. detach the control pot and mount that on the handle with the guts of the servo tester on the plane. If you're building your own circuit this is probably easiest.

2. Run the whole tester on the handle and send the pulses down the wires. I found this worked fine if ran the tester off 9V to account for losses down the wires. I stuck a 5V zener on the input to the ESC just in case. Doing it this way has the advantage that you could extend it to more channels (like the scale guys, retracts, bombs etc) if you needed them.

I've only tried these on test rigs not serious C/L planes. I have a little all sheet thing with S400 and 7 cells on 25ft lines that can barely keep itself in the air but it's enough to prove that you can control the motor speed at will. The ability to wander gently out to the centre of the circle and just switch on is great (there's not a lot of C/L interest round here so I tend to fly alone, if at all).

I then got sidetracked trying to do it without the heavy draggy insulated wires (infra-red etc). Perhaps it's time to go back to basics and do some flying.

Steve

[jrb]

Steve,

Great report! Can you post any sketches, drawings, photos, or schematics of what you've done?

Been thinking about some other schemes.

Does a C/L plane need "air" freqs or sinec its tethered to the ground is "surface" suitable?

Too bad about the demotion; but if it quiets a loud crowd OK. Just wish that there was a indicator on the main page that there is a new posting in the "special interest" area.

Later,

Jim

[Darwinn]

Does a C/L plane need "air" freqs or sinec its tethered to the ground is "surface" suitable?

I fly at Scobee Field in Houston which is a large multi-use model field. I checked with the safety boss at the RC side of the field and asked him if it would bother anyone to use a car radio over at the controline circles and he had no problem with it. I would stick to ground frequencies to avoid any possible interference with RC aircraft. I plan to use 27 mhz to make it even less likely. Throttling isn't much of an issue in regular controline competition yet much less in electric experimenting. It's not like an AMA SWAT team is going to swoop in and bust anyone for using a "ground" frequency for a controliner. The safety problem of interference from RC cars or boats is present but far less of a issue with a tethered device. Using an RC car transmitter and receiver just seems so much easier than rigging up timer cutoff relays or down the wire control setups.

[steve lewin]

Up to you of course Darwinn but at least over here in the UK it is illegal to use ground frequencies to control a flying model and whatever else you say C/L models do fly.

As it happens 27MHz would be o.k. in that sense because it is allowed for any models, ground or air. I guess that must be true in the US too since so many of the cheapo plastic park flyers come with 27MHz radios.

Let us know how you get on. Personally I'm still trying to get infra-red working correctly. There are no regs about that as far as I know and it does remove the need for insulated lines.

Steve
(jrb, I'm drawing up the circuits I'm currently using. They should be on a website sometime this week with luck. I'll let you know when and where)

[jrb]

Steve, look forward to seeing your site.

Darwinn, think 27Mhz woudl keep the SWAT teams off our a**; but probably will try something with one of those prolific 75Mhz handles.

I wonder, for what part/percentage of its mission does something have to remain of the ground to be considered a "surface" model?

Sometimes it seem that off road cars/trucks are off the ground quite a bit and some of those other car types sure seem to fly!

[Darwinn]

It would not be too hard to adapt an RC car transmitter to a handle configuration but what I'm wondering is whether or not it would be better to have the controls separated so that one's handle hand is only concerned with controling the flight path of the airplane. Fiddling with a trigger or button on the handle for throttle could compromise the solid yet delicate grip needed for aerobatics. I know scale folks have all sorts of functions on the handle but their flight profiles do not usually require the same sort of aerobatic complexity that a stunt ship does. Putting the throttle control in the other hand, it seems to me, would give one rather more precise flexibility in controling the aircraft's speed. This is assuming we can ever get to the point where an electric will have enough power to make this an issue. As it stands now a simple switch is probably all that's needed.

[jrb]

Agree that the car controller might not be the best config for the control handle.

Wearing a TX on the belt is how I've seen the scale guys do it.

You would think that the AMA would lobby that if its tethered to the surface then it should use a surface radio -- could have RC and CL events at the same site as you suggested!

If a switch is all that you want and you can deal with electric control lines, them the relay circuit I shown in the other thread could be easily modified to acomplish that.

[steve lewin]

I've also just modified the servo tester to work as a switch rather than proportional control. I can't resist fiddling with things. Circuits will be on http://www.slewin.clara.net/elec/ecl.htm in the next day or so.

Steve

[jrb]

Steve,

Can the servo tester the be used by either a pot or a switch?

Assume either still require 2 "electric"/flight control lines?

If you can let when you get the stuff posted.

[steve lewin]

O.K. what I have is on there but I warn you it's not very exciting. I'll put a picture or two up there if I ever get out flying again.

Good luck - Steve

[jrb]

Steve,

Looks great!

Can only anticipate that the photos will be even better!

Really like the "Remote" version, since you'd only need one for your fleet of CL planes.

You might want to change "(R5)" in the switch version test to "(VR1)" on your next edit; that is if that's correct.

Suppose there are linear 47k pots readily available to make the trigger design easier. Any different ideas on trigger configurations?

[steve lewin]

Just in case anyone is thinking of building any of those circuits of mine please make sure you have the latest versions. The original ones I posted were rubbish (1 wrong connection and a couple of pins on the 555 swapped over). They're o.k. now.

I was half inclined to leave as they were to see if anyone ever tried to use them but that would have been unkind :).

Jim, I'm rotten at mechanical design so I'm just twiddling a rotary pot with my other hand at the moment. I did see a simple design somewhere using a slide pot moved with the thumb and a rubber band as a "return spring". If I can find the article it was in I'll post a picture or two of it.

It's not easy to get 47K in sliders but you can use a double gang 100K with both sides connected in parallel or, simpler still, use only part of the movement. Since we're only using it as a variable resistor it doesn't matter if you only use half the available movement to give you 50K and that probably works out better mechanically.

Steve

[jrb]

Its been a long while; I really thought this (ECL) pot would have started boiling by now!

Some updates:

Cox has an ECL; anybody seen it, flown it?

I’ve been watching the progress of a “DIY IR System” in this thread: http://www.rcgroups.com/forums/showthread.php?threadid=24711&perpage=15&pagenumber=10 , with thought that maybe it could be applied to ECL.

Imagine an IR TX is mounted an a Control Handle and the IR detector on the side of an ECL plane! A single channel is all that would be needed for throttle only.


Does anybody else have anything new?


Here’s an idea for a new technology servo tester: http://www.rcgroups.com/forums/showthread.php?threadid=94261 referencing – http://www.rc-cam.com/servotst.htm


I haven’t done anything including what I had planned using an RC Car system posted here: http://www.rcgroups.com/forums/showthread.php?threadid=23595

Also here’s the famous relay circuit: http://www.rcgroups.com/forums/showthread.php?threadid=9642


Jim

[Mike Palko]

I have a bunch of friends that are using the ztron setup in there IC C/L models. They use it to control throttle and landing gear ect.... I guess that would work for electric also. I had never really thought about it. I will have to try it out and let you guys know.

I have also built on of Steve's servo testers. It works fine in the basement but when i go to the field and try to fly it i get alot of interference and then the motor almost completely shuts off. I found the problem to be the cold weather. If i blow on the servo tester or hold it in my hand the motor turns faster and faster as it warms up. I think the problem is that the resistors resist less when they are cold(20-30 deg).

I am building a small indoor control line plane right now. The club i belong to is putting on a demo/display at a local hooby show and we plan on flying it as part of the demo. I have also been building a Nobler that is going to be ECL. That project is kind of on hold. I decided to design from the ground up a plane for ecl and then the indoor model came along so i need to get back onto the nobler.

Sorry this kind of turned into an update of what i have been doing rather than a servo tester response.

[steve lewin]

Originally posted by jrb
I’ve been watching the progress of a “DIY IR System” in this thread: http://www.rcgroups.com/forums/showthread.php?threadid=24711&perpage=15&pagenumber=10 , with thought that maybe it could be applied to ECL.

Imagine an IR TX is mounted an a Control Handle and the IR detector on the side of an ECL plane! A single channel is all that would be needed for throttle only.


Well I've had one of those working for a while if anyone is interested. As Mike says you can buy a similar setup from Ztron. If it works a throttle servo it will work a speed controller.

I have 2 versions, a simple on-off switch and a proportional version. That actually has 4 channels but I've only really tested them briefly. I haven't actually flown the proportional version yet but it seems o.k. in the workshop. I've built that one using a PIC microcontroller so it needs the ability to program PICs. The on-off version is simple discrete components though I might convert that to PIC too, it would be much smaller. Let me know if you need the circuits.

Mike, I confess I hadn't thought about the effect of cold on the servo tester (I stay at home when it's that cold). Below freezing even the chip can have problems. Are you using a standard 555 or the CMOS 7555 version ? Generally the CMOS ones are slightly better at extremes.

Steve

[Mike Palko]

Steve i am using the standard 555. I guess waiting for a nice day to fly is going to be longer than i thought. Now it has to be warm to. :mad: The ztron setup has got me excited now! I can't believe that other members of my club have been using them for about a year and i never thought of applying it to electric. Oh well i still have a month or two to get some of my setups figured out then.

[steve lewin]

The Ztron IR setup is interesting. When I attempted to fly my first proportional IR gear I had a lot of trouble with it "glitching" in strong sunlight, particularly coming round from shade into sun. Sergio has obviously sorted that out. It may be that the inertia of a servo and throttle makes it less of a problem with IC engines or it may simply be that he knows a lot more about designing IR systems than I do :( (not difficult, I'm a complete amateur in this area).

The other thing is that the handle may not be the place to mount the emitters. I think Windy U had them on his hat didn't he ? It's amazing how often in normal flying that the handle isn't really pointing very close to the plane at all, but I expect you know that ;).

Steve

[Mike Palko]

I posted a response the other day but i guess it didn't work. Oh well, i am using the standard 555 chip. I talked to some of my friends about the ztron unit. They couldn't remember the exact price but they remebered it being around $100. They also said that it was proportional. The only draw back is that no matter what controller you have it will work any airplane (i guess i should say reciever). They use an infa-red light beam to send the information to the airplane. We are going to look into different "frequencys" or what ever you would call it. Since your tv, vcr, dvd ect... controllers only control on thing at a time there must be a way to have many differant planes flying at once. Maybe somebody knows more about it than we do? I can't wait to try one out. I'll keep you posted.

[steve lewin]

I have been doing some research into this subject but there's a lot I don't yet know ;).

TV remotes work by using fairly complex digital codes. The main problem with that is it means they're very slow, particularly since most of the common decoder chips rely on seeing 2 or 3 identical copies of a good code in a row before they do anything. That means they need a very clean signal because any missed pulse causes them to reset and start looking again for a "good" command. In turn that dramatically reduces their effective range.

Ztron IR controls work more like radio control but unfortunately there's no easy way to provide many different "frequencies" because that's built in to the sensor chip. You can buy them on 3 or 4 different frequencies but you can't switch frequency at the Rx end without replacing the whole sensor (they only cost a dollar or two, but it's a pain having to swap them out).

Still, as IR control gets more popular it's likely that someone will sort the problem out. I believe it could be solved now by using simple IR detectors instead of the integrated IR receivers. But that would mean more complexity and cost as all the filtering and decoding would have to be done by Ztron etc rather than the semiconductor manufacturer. It will be interesting to follow what happens.

But I wonder how much of a real problem it is. The emitters are fairly directional and the receiver in the plane can be very directional. It's nothing like radio where both transmitter and receiver are omni-directional. There's not very much chance of 2 fliers both pointing at the same plane is there ? Unless you're flying combat, of course.

Steve

[Mike Palko]

Steve thanks for the info. Sounds to me like you know quite a bit about this subject. I guess just about every body knows Windy Urtnowski! He is a great guy and has dedicated his life to r&d for model airplanes. I think this year i am going to learn alot about electric C/L. I guess time will tell.