throttle for RC motor

Sinewave

10 mW
Joined
Oct 19, 2008
Messages
34
has anyone been able to use a twist grip throttle for use with an RC motor and rc speed controller?
 
You need what is known as a "servo tester", there are several brands available, the Astro Flight seems to be the most popular. You will have to do a bit of soldering to change the potentiometer in the tester over to the twist throttle.

Here is a link to a servo tester/wattmeter combination although there seems to be some question as to quality control with it.

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=6553&Product_Name=TURNIGY_Multi-F_DC_Watt_Meter_75A
 
You can also build a servo tester from a LM555 and some resistors/capacitors. Several schematics are on the web.
Servo Tester Schematic.jpg
 
so i take it theres no commercially available throttle for rc motors at the moment?

solderings not a problem , i fix car amplifiers for extra income. :)
 
There are no commercial RC controllers that take a direct voltage input for PWM control. They all take a PWM input.
 
johnrobholmes said:
There are no commercial RC controllers that take a direct voltage input for PWM control. They all take a PWM input.

And that input PWM signal originated from where, please, John. Further, the pics of the RC controllers I've seen look like it wouldn't be too hard to get at the PCB. So, I'm wondering how tough it would be to bypass the pwm input section and insert a throttle signal on it's output. Then there's the matter of a +5 volt throttle input. I wonder if that's available on the controller PCB.

ATB

BC
 
The PWM comes from either a receiver, servo tester, or home built device. A servo tester can be modulated with a 5k pot style throttle, and possibly even a hall effect throttle.
 
I've done a little probing around on my esc and haven't found anything that would indicate the ability of the microcontroller to be able to accept an analog type 0-5V input. The actual pulsed output 1-2ms from your reciever/servo tester generally goes directly to the chip (It may go through a protection circuit before hand, but that was all I could find. Not to say that it wouldnt be possible to make a controller that could do this, but you'd have to be able to program the microcontroller and build the controller which wouldn't be a very easy task.
 
Check with Astro Flight. This throttle http://www.astroflight.com/index.php?main_page=product_info&cPath=20&products_id=144 is supposedly a 1.5 to 2 second PWM output that will drive an RC conrtroller. Call them and ask. I have heard it is compatible. But, I haven't talked to them.

Matt
 
I deleted my previous post because I just clicked the link that showed the twist grip throttle. The astrolight servotester I used previously was the standard knob type which did work fine with my castle hv85 controller. It's cool that Astroflight is jumping into our market! I look forward to trying some of their products out in the future.
 
Matt,
Are you saying the knob on that Turnigy Wattmeter will act as a throttle, or does it just adjust the modulation, and you still need a servotester?
Can I just use a line directly out of the ESC to a potentiometer knob from say Radio Shack? And if so, which ohm variance?
 
The knob on the Turnigy wattmeter will function as a throttle for an rc esc it has a servo tester built in and will produce a 1-2ms pulse. The other nice thing is that it also provides power to the rc esc through your main battery pack. The unfortunate thing is that the unit should be kept close to your batteries unless you want some pretty thick wire running up to your handle bars. I decided to desolder the display and throttle knob, I then added about 5 feet of 22gauge and ran them up to my handle bars where I could use them. I would not attempt this however unless you have desoldered multipin fixtures like the display even with the right tools it can be a bear.
 
This watt meter seems to be the best.
mprv3-angle-sm.gif
powerpanel-angle.gif

So many plug in options, you could really spend alot of coin on something like this. Maybe one of these days we will finally get our heads up display, like that power panel, except in my sunglasses 8)

I don't see any sort of servo tester outlet though.
http://www.eagletreesystems.com/MicroPower/micro.htm
 
Here you go...........

http://www.astroflight.com/index.php?main_page=product_info&products_id=19

Oh, I have that Eagle Tree setup. VERRRRRRY nice! :mrgreen:

You should check out the stuff Dimention Engineering makes too. They have some cool RC and robotics stuff.

Matt
 
John, as far as tools go for desoldering I've used both wicks and solder suckers. When I can get to the back of the hole for good suction I'll normally use my sucker... the sucker I use is labeled the soldapult and it does a great job. I've tried the radio shack branded sucker and it was lame in comparison it didnt create enough suction to completely clear out the holes. If you are having problems then I go back through and see if I can pull anything else out with some wick... The key to this is using a good flux. If you drip some liquid flux onto the wick you'll have a much better chance of getting the solder to flow into it well. The best flux I've used is a liquid type designed to be cleaned as it will crystalize over time on the circuit board. I don't have the name handy, but I can probably get it monday when I go to work. It flows solder like no other, but you'll have to brush the board off with some alcohol because the crystals that form over time are a bit conductive and can/will cause gremlins in the future if not properly cleaned. Another method I've used but am currently out of is using a kind of low temp solder like Chip Quick. In this instance you basically glob up the solder across all of the pins and since the melting temp is low around 200 deg you can remove what you want without damaging the board. When resoldering on the board I can share with you one last tip I learned in our test section at work. Keep the tip of your iron well tinned and add flux to whatever your soldering and then just pick up a small amount of solder onto the tip of your iron touch the tip to what your soldering for just a second or two and watch the pad and pin pull the perfect amount of solder onto itself. As a word of caution though keep the temp on the soldering gun below 600 degrees when working on a board to prevent damaging components and the board, and always practice on a junk board before you attempt a project on something you want to keep working.
 
OK, so I just got all the parts for Matt's throttle from his recumbent build. But before I get started I was wondering if somebody knows how to use a three wire throttle such as a magura instead of the knob he uses. Or at least, the additional parts I need would be nice, any help will be appreciated though. Don't get me wrong, Matt's would be ideal for putting down some miles (or km), but for dirt action I think a thumb or twist throttle would be better.
 
There is at leat one member here running one. From what I have been told, the entire setup they make for bikes is only for brushed motors. But, the controller and throttle use typical 1.5ms pulse for RC use, so you can use just their throttle into a standard brushless ESC. I haven't tried it myself, though. It would be good to call them and ask.

Matt
 
I have one of their brushed controller/throttle combos. The throttle is just a standard Magura one, with a 5K pot. The controller itself has been modified to voltage control, I guess.

The new Castle Creation controllers will be the way to go, for a simple set-up :D
 
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