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

Hillhater said:
Jeremy Harris said:
OK, I've had a go at making a simple Picaxe interface this morning.
...... Here's a quick description of what I did.
Jeremy

Your knowledge and abilities exceed even my capacity to understand WTF you are saying !!! :shock: :lol: :lol: :wink: )

.... but it sure sounds like a good idea !


ROFL...don't worry...Jeremy's words and actions have that effect on alot of people, in fact hahaa, I should probably
be the president of the 'WTF is Jeremy Saying' club :mrgreen:

Keep up the good work Jeremy....i think, your not making weapons of mass destruction are you? :shock: :mrgreen:
You remind me of this chap you have something else in common
too, he was also on a episode of Scrap Heap Challenge, he helped one of the teams build a pulse jet.

KiM
 
Thanks for the kind words and sorry for the furrowing of brows I've caused................

In essence, all this chip is doing is reading the value of the voltage from the Hall throttle and directly converting it into the right type of pulsed signal to drive an ESC. It helps not to think about the chip as a microcontroller, but just think of it as a very versatile electronic building block that can convert signals from one form to another, in pretty much any way you want, just by changing a few lines of code, rather than by changing components.

BTW, I know Bruce. As well as being a fellow Scrapheap expert, he's also done some pretty remarkable stuff with pulse jets. I managed to scare the **it out of some folks where I used to work when I showed the anti-terrorist team his 'Build a cruise missile for less than $5000' site a few years ago. Even better are some of his other pulse jet projects, like the pulse jet powered go kart. I bet his neighbours love him as much as the CIA and NZ government (anyone who's heard a pulse jet run will know what I mean.........).

There must be something about Kiwis that makes them even more eccentric than us Brits, this guy: http://www.asciimation.co.nz/ for example, is another Kiwi with way too much time on his hands and some truly brilliant projects (check out the turbojet-powered beer cooler...........).

Jeremy
 
Looks good Jeremy,

I would right-shift by 7 (essentially divide by 128) instead of
Code:
ppm_output = ppm_output / 130
ie
Code:
ppm_output = ppm_output >> 7
 
full-throttle said:
Looks good Jeremy,

I would right-shift by 7 (essentially divide by 128) instead of
Code:
ppm_output = ppm_output / 130
ie
Code:
ppm_output = ppm_output >> 7

Shift right isn't a valid operator on the 08M Picaxe, plus the divisor needs to be 130 to get the correct value of pulse width.

Jeremy
 
ok, got my throttle up and running, and i can confirm that for the electrics i got it works. i used the same jumper method in the picture a page or so ago on a turnigy servo tester, and the cheapest hall effect throttle i could find.

throttle i got (10 bucks posted on ebay):
http://cgi.ebay.com/ebaymotors/Razor-Electric-Scooter-Throttle-Twist-Grip-24V-36V-48vB-_W0QQcmdZViewItemQQhashZitem3cb063f61aQQitemZ260657378842QQptZLHQ5fDefaultDomainQ5f100#ht_4496wt_939


servo tester (the turnigy one for 6 bucks, jeremy said they may change the electrics, but the ones they were supplying a month ago work):
http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=8296

am yet to test the final rpm (need a few more parts as i only have the cycle computer to measure speed, then deduce rpm) but the esc has a little led in it that lights up at about 90% of the twist, so i am taking it this led means that the esc is full throttle. otherwise it seems smooth and consistent with the more twist it gets.

total cost for parts shipped to your door would be less than $20, then you will need a 4-6v power source (ubec) for the servo tester, as you would if using the magura throttle. for any interested i am just using the cheapie k-force 120 esc for now, see how it holds up for my first build.
 
lol, good to see your on the ball hillhater, but dw, i already trimmed that button off and taped the whole thing up ready to shove into a box :D
 
If I want to use the turnigy ST on a CC 110 HV using a hall thumb throttle I will need to use a BEC. How would we wire the BEC into the servo tester? would it be similar to how Matt has done his?
I got lost in what Jeremy was saying which I think was about this. If anyone could do give some explanation as I have ordred the turnigy and would like to have a go at wiring it up.

Cheers
 
for mine i simply plugged the bec into one of the 3 servo places, right under where the esc went in.

means the power is being put in "reverse" direction but it is all the same.
 
I see it now, I thought their was just one input & output but I can see the multiple plug points.
Thanks
 
Depending on your input voltage

This unit is good for 10s Lipo input
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=10313
Very cheap site and they have many warehouses around the globe :)
 
Hey Guys,

I wanted to post a quick update..........

I spent the morning building a bunch of throttle interfaces. All pending orders are filled and I have two throttles finished in stock. :)

Sorry for the delay. I had an issue with regulators and a couple other minor details. I am up to speed again, however. :)

Matt
 
bandaro said:
ok, got my throttle up and running, and i can confirm that for the electrics i got it works. i used the same jumper method in the picture a page or so ago on a turnigy servo tester, and the cheapest hall effect throttle i could find.

am yet to test the final rpm (need a few more parts as i only have the cycle computer to measure speed, then deduce rpm) but the esc has a little led in it that lights up at about 90% of the twist, so i am taking it this led means that the esc is full throttle. otherwise it seems smooth and consistent with the more twist it gets.

for any interested i am just using the cheapie k-force 120 esc for now, see how it holds up for my first build.
Hi Bandaro, just thought I'd check-in to see how the rpm range worked with this setup? You got full range & good control w/throttle you bought? Also, how is that 120 k-force ESC working? Did you add extra caps or mod it?

Thanks! :mrgreen:
 
recumpence said:
Hey Guys,

I wanted to post a quick update..........

I spent the morning building a bunch of throttle interfaces. All pending orders are filled and I have two throttles finished in stock. :)

Sorry for the delay. I had an issue with regulators and a couple other minor details. I am up to speed again, however. :)

Matt

What all do your throttles consist of? What features do they have?

I just finished mine, with a 0-5k sliding pot (in a custom cable throttle box) to a Turnigy servo tester to a servo speed regulator then to the esc's.
 
HumboldtRc said:
recumpence said:
Hey Guys,

I wanted to post a quick update..........

I spent the morning building a bunch of throttle interfaces. All pending orders are filled and I have two throttles finished in stock. :)

Sorry for the delay. I had an issue with regulators and a couple other minor details. I am up to speed again, however. :)

Matt

What all do your throttles consist of? What features do they have?

I just finished mine, with a 0-5k sliding pot (in a custom cable throttle box) to a Turnigy servo tester to a servo speed regulator then to the esc's.

It is a simple PWM board with 5v regulator to power it in a water resistant heat shrinked package with a Magura twist grip throttle. :)

It is a tried and tested design. All units are hand built and bench tested before shipping.

Matt
 
Wow, good stuff in this thread!

I wanted to get some advice on two parts however.

1) I had some real trouble removing the Servo Tester POT even with my 60W iron (I tired it first with my 30W to avoid getting things too hot) and I am still not 100% sure that I didn't damage the PCB in the process, I have been considering getting a "vacuum bulb" designed to suck away the solder, but for now I have been using the heat and tap method, and also tried by heating all three leads at once on the POT, but I REALLY struggled to get it loose even when I had all the leads just sitting on the PCB. Is there something I am missing? I have to work in a pretty cold (about 55 DEG F) garage, maybe that is part of the problem.

2) I am unclear about weather or not I should be fine using the BEC on my ESC to power the Magura Throttle, or if I will still need to add an extra BEC to power things?

Oh, one more thing, I got to wondering since using the extra POT that I removed from the ST, if I understand correctly using it as a "throttle limiter" restricts total voltage, and say if I wanted to run 8S and regulate down the speed, that although it wouldn't regulate amps, would I not be able to have it regulate the voltage down so that it could at as if I were just running 6S while under higher load (climbing hills) and then turn it back up for a long flat stretch. Am I correct in my understanding?

Thanks! :)
 
1) I am a soldering idiot, and couldn't desolder the POT. So I just got got some side cutters and cut each leg on the POT. POT fell off. Job done. :D

2) ESC BEC should be fine.

3) Give it a go. Put a POT on the 5V rail into the magura throttle POT (you can use the one you clipped off).
One thing to note is that your ESC will have a bit of a harder life, running at partial throttle on 8S, rather than full throttle on 6S, since it will be generating more heat by having to PWM more to reduce voltage at the motor.

Good luck.

- Adrian
 
LI-ghtcycle said:
Wow, good stuff in this thread!

I wanted to get some advice on two parts however.

1) I had some real trouble removing the Servo Tester POT even with my 60W iron (I tired it first with my 30W to avoid getting things too hot) and I am still not 100% sure that I didn't damage the PCB in the process, I have been considering getting a "vacuum bulb" designed to suck away the solder, but for now I have been using the heat and tap method, and also tried by heating all three leads at once on the POT, but I REALLY struggled to get it loose even when I had all the leads just sitting on the PCB. Is there something I am missing? I have to work in a pretty cold (about 55 DEG F) garage, maybe that is part of the problem.

2) I am unclear about weather or not I should be fine using the BEC on my ESC to power the Magura Throttle, or if I will still need to add an extra BEC to power things?

Oh, one more thing, I got to wondering since using the extra POT that I removed from the ST, if I understand correctly using it as a "throttle limiter" restricts total voltage, and say if I wanted to run 8S and regulate down the speed, that although it wouldn't regulate amps, would I not be able to have it regulate the voltage down so that it could at as if I were just running 6S while under higher load (climbing hills) and then turn it back up for a long flat stretch. Am I correct in my understanding?

Thanks! :)

If your ESC has a BEC that is functional at the voltage you are running, you do not need to add one to your throttle. You just need the PWM board (servo tester) and the throttle in place of the POT.

Oh, BTW, I just clip the POT legs too. Trying to desolder them is a pain..........

Matt
 
Ahhh, that makes sense! Unfortunately my particular brand of ST wouldn't have made it any easier to clip the legs of the POT. Not enough room in there. I'll have to try again with one of the Turngy ST's like Hillhater bought from HK (assuming his one wire mod would work the same for a POT throttle?) if mine is too fried.
 
IT LIVES!!!! :D :D :D

I guess my solder torture wasn't too bad, I fired it up with the throttle and got a satisfying "turbine whine" from my new motor!

Thanks again everyone! 8)
 
Ok, now I'm puzzled, I have the ESC and motor wired properly, but the motor is going backwards. Could I have 2 leads reversed in the throttle interface? I guess I could always swap the neg and positive leads from ESC to motor, but I'd rather figure out what is causing this and fix it properly.

Any ideas?

Thanks!
 
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