RC throttle interface build tutorial........

[ron van sommeren]

Servo-tester circuit
http://www.drivecalc.de/
-> Servo Driver eliminating the need for a receiver ...

Vriendelijke groeten Ron
• brushless motor building tips & tricks • diy brushless motor discussion group
• Drive Calculator download & discussion group • int. electric fly-in, Nijmegen, the Netherlands

[mclovin]

After we wire and solder it all up.....is there anything we need to do to the controller? Is there some type of calibration involved? If this sounds like a strange question allow me to clarify.

As I understand it, the FETs allow current to "pass" during the time they are on (duty cycle). If we are into low speed cruising from time to time and barely twist the throttle then the FETs will have a very short duty cycle BUT may still heat up when they are inbetween pulses. Is this correct? If so do we need to ensure a minimum duty cycle - minimum command voltage (oh, like 50% of battery V) or is this a non-issue?

Thanks!

[Grinhill]

If so do we need to ensure a minimum duty cycle - minimum command voltage (oh, like 50% of battery V) or is this a non-issue?

The throttle pulses aren't used to drive the output stage directly, there's a microcontroller in between in the ESC.

When you first power it up, the ESC looks for a baseline stream of pulses (1 millisecond width) which corresponds to zero throttle. If it sees these pulses, it then goes in to idle (motor stationary, ready to start).

Opening the throttle increases the pulse width proportionately, up to a max of 2 milliseconds, which is what this interface circuit does. The ESC takes care of the rest (i.e. spinning the motor).

[mclovin]

If so do we need to ensure a minimum duty cycle - minimum command voltage (oh, like 50% of battery V) or is this a non-issue?

The throttle pulses aren't used to drive the output stage directly, there's a microcontroller in between in the ESC.

When you first power it up, the ESC looks for a baseline stream of pulses (1 millisecond width) which corresponds to zero throttle. If it sees these pulses, it then goes in to idle (motor stationary, ready to start).

Opening the throttle increases the pulse width proportionately, up to a max of 2 milliseconds, which is what this interface circuit does. The ESC takes care of the rest (i.e. spinning the motor).

I don't want to muck up Matt's tutorial string so I will post this as a seperate topic. Thanks for the info.

Cheers.

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EDIT I started a thread here: http://endless-sphere.com/forums/viewtopic.php?f=28&t=12293

[spinningmagnets]

The throttle is now finished, ready to use! You merely supply 24 to 48 volts to the black and red input wires...

Matt, sorry for a newbie question, but many of the friction-drive RC builds are using 5S and 6S (18.5V / 22.2V). What changes would I have to make to this Magura throttle adaptation, or is a generic servo-tester really the best option for the lower-powered set-ups? (I don't even know if I'm asking the right question...)

[bandaro]

so if i have a hall effect throttle can i just do the same thing and replace the potentiometer in the tester with the hall or what?

im thinking i wont be able to, but i dont know how either works so im not sure...

[recumpence]

The throttle is now finished, ready to use! You merely supply 24 to 48 volts to the black and red input wires...

Matt, sorry for a newbie question, but many of the friction-drive RC builds are using 5S and 6S (18.5V / 22.2V). What changes would I have to make to this Magura throttle adaptation, or is a generic servo-tester really the best option for the lower-powered set-ups? (I don't even know if I'm asking the right question...)

My current throttle I am building uses a very wide range input regulator. You can go as low as 6 volts input, if I remember correctly.

Matt

[Hillhater]

Just for info and to help anyone starting out ..
I just tackled this ESC /servo tester throttle mod using the Turnigy servo tester .
http://www.hobbycity.com/hobbyking/stor ... rvo_Tester

PS.. initially i thought i had screwed up and got the wrong servo tester. ! but....
This actually proved simpler than the others, requiring only the insertion of one jumper (after removal of the pot) from the input "signal " pin ,to the centre pin of the potentiometer socket.


So when used with an ESC /BEC , you can simply connect the throttle via the "input" socket of the (modified) servo tester and away you go !
Nice simple , quick , clean throttle interface. !
To recap..
1) remove the potentiometer.
2) insert a jumper lead from the input signal pin to the potentiometer socket centre pin location.
3) reassemble and plug in your throttle.

And for Spinningmagnets.. this is used on an 18.5 V system, Turnigy Kforce 100A ESC, with the 63-54 motor, and a Hall effect thumb throttle.

[spinningmagnets]

2) insert a jumper lead from the input signal pin to the potentiometer socket centre pin location.

Hillhater, could you please post a pic of this, perhaps add a red arrow?...

(also...thanks for the reply, Matt!)

edit: WOW! only $6, but they are now back-ordered!!...now waiting for another Hobby king email that stock is back in...

EDIT 2: Thanks for adding the pics! its great to have several RC-throttle options detailed in one thread (with prices, pics, part #'s, and links)

[Byte]

Don't you need a servo tester with a 5K pot to use it? This one has a 9.35K pot I believe.

[recumpence]

The POT resistance does not matter, ironically.

Matt

[Kepler]

I have built this servo tester a few times. Its about as simple as it gets. Very easy to build and you get the parts from your local electronics supplier for a few dollars. Still easier to use to convert an existing but is a viable alternative.

[Miles]

Wrong file uploaded, I think Either that or a coincidence of file names.......

[AussieJester]

And a glimpse of what Kepler has planned next maybe

KiM

[Hillhater]

2) insert a jumper lead from the input signal pin to the potentiometer socket centre pin location.

Hillhater, could you please post a pic of this, perhaps add a red arrow?...
...

Ooops ! .. sorry did a green arrow instead of red !

[bandaro]

so any idea on the hall effect throttle replacing the pot throttle? will it work?

[Hillhater]

so any idea on the hall effect throttle replacing the pot throttle? will it work?

I am using a Hall throttle with the turnigy set up described previously. No problems.
. .well actually i am still having a lot of issues with "sync failure" under load, ...but that is nothing to do with the throttle.

[jag]

so any idea on the hall effect throttle replacing the pot throttle? will it work?

I am using a Hall throttle with the turnigy set up described previously. No problems.
. .well actually i am still having a lot of issues with "sync failure" under load, ...but that is nothing to do with the throttle.

The ability to use a hall throttle is good news. No potentiometer track to wear out, and quality hall throttles seem cheaper than quality pot throttles.

Are there any issues with the different characteristics for halls? ie the throttle response curve seem wierd? or is missing top and bottom part?

[Kepler]

Wrong file uploaded, I think Either that or a coincidence of file names.......

Opps. I'm a duffa. All fixed

[Kepler]

so any idea on the hall effect throttle replacing the pot throttle? will it work?

I am using a Hall throttle with the turnigy set up described previously. No problems.
. .well actually i am still having a lot of issues with "sync failure" under load, ...but that is nothing to do with the throttle.

Hold the phone!!!

You are using a Hall effect throttle where a 5K was used just by putting in a jumper? You have gone from a resistive change to a voltage change. This needs more explanation on how this works.

You didnt tell us this when you were talking about sync issues. I wonder if your setup has lost resolution and pulse width is increasing too quickly at the lower end of your throttle range now.

The prototype interface I am involved with at the moment can run a Hall or a 5K throttle but needs a different range set to provide the correct output when changing from one to another. Subsequently it needs a processor and software to do this.

Has anyone else modified a servo tester to take a hall throttle or have I just not been paying enough attention. Lets face it, who want to spend $50 bucks on a magura, when you can buy a Hall throttle for $12

[Hillhater]

You are using a Hall effect throttle where a 5K was used just by putting in a jumper? You have gone from a resistive change to a voltage change. This needs more explanation on how this works..

Sorry Kep' im no sparky just a "suck it and see" idiot with a hot soldering iron !
The shop that sold me the throttles said they were Hall effect so i simply hooked up the wiring ,black to -ve, red to +ve and white to "S" inputs on the servo tester and then "jumped the "S" input pin to the mid socket of the pot location.
( note, on the Turnigy Servo tester inputs, +ve and -ve both link direct to the other pot sockets, and the "S" pin is not connected to the board circuits)
The end result seems to work fine , but i will check with a tach' to be sure i am not missing any range.

You didnt tell us this when you were talking about sync issues. I wonder if your setup has lost resolution and pulse width is increasing too quickly at the lower end of your throttle range now.

Unfortunately, the "sync " issues were there before i wired up the throttle...just using the servo tester "au naturale" , and they persist unchanged after install.
I have to peddle up to about 20kph before powering up the drive, to have any chance of avoiding "sync failure"
I guess i am going to have to try another motor...or ESC !!

[Miles]

And a glimpse of what Kepler has planned next maybe

That's a Hal production

http://endless-sphere.com/forums/viewto ... 08#p130908

[bandaro]

waaaiiiiittttt.....


hillhater, yours is done different from the one first posted up right? you put the jumper in and then connected the throttle to the "in" side and your esc has a bec inbuild so you used that to power the tester right? with the power coming through the tester backwards (starting at the "out" side)?

i got the turnigy tester sitting in front of me and it appears that signal wire on the "in" side is not connected to anything, so if the above is not right then im well and truly confudled. you just did this for building simplicity?

[Hillhater]

When you run the ESC ( with BEC) with just a servo tester you simply plug the ESC into the "output" side of the ST... then use the ST as the throttle.
So you dont need the power feed to the "input" side of the ST.
when you remove the pot from the ST, and trace the circuit you will see how the +ve and -ve input pins are fed to the two outer pot connections, so using them to link to the throttle was logical ( to my tiny mind at least).
Then as you say, seeing the S input pin was not actually connected, i simply "jumpered" it to the centre pot connection on the board.
This gives me a "plug in" throttle connection.
As you say i did this for simplicity ( and in total ignorance of if it would work !) but it seem to function perfectly.....so far !

[bandaro]

awesome, then thats good enough for me, i can see anything wrong with it apart from the basic possible problem of hall vs pot.

does someone who understands all this electrical component stuff see a reason why the hall cant simply replace a pot? as it stands i think ill just solder up an identical circuit as hillhater, and cross my fingers, lift the rear wheel off the ground and make sure the wheel speed it right to test full throttle rpm.