Speed Control - brushed?

[elfergos]

I just refurbished my old Grasshopper but was wondering about speed control, there doesn't seem to be a great deal of variable resistance between when the motor is not running and it being full speed. Are there better resistors or is this a property of brushless motors?

[atom3624]

Are you still running the mechanical speed controller, needing the servo to slide the contact?

There are LOADS of brushed electronic speed controllers out there that will suit, without going BL if you want.

 

Al.

[elfergos]

Yeah I'm still using the stock servo, arm and slider contact, it still works as far as I remember like it did 20 years ago but there isn't much in the way of speed control, its virtually either just on or off, sort of digital rather than analogue.

 

 

Would something like this fit with what I need:

http://www.modelsport.co.uk/etronix-probe-plus-brushed-esc/rc-car-products/367600 ?

 

Are they difficult to install?

Edited August 20, 2014 by elfergos

[Noj]

That will work fine, and is auto set up, so once it has detected neutral, you'll be good to go. It is also lipo compatible (with the use of an independent alarm) so you have that option available should you wish to use it   I run the wp version in tamiya's on 2s lipo with good results 

[elfergos]

Thanks,

 

I'm a complete noob when it comes to building RC cars, does this replace the stock servo, arm and slider contact? Or to put it another way is the ESC a type of servo or a servo replacement?

[Noj]

It replaces the entire mech system as you described, and also does away with the old, four cell plug in battery box, which you required to power the Rx; the Rx draws power from the main battery, via the ESC.

Steering servo into channel 1, ESC into channel two, and voila. Just ensure to plug in correctly, ie, with the negative lead from the ESC to the rhs (ie outside edge) of your Rx (like you connect the steering servo really )

Hth

[elfergos]

OK, I installed the ESC and ran in to some problems with the motor stuttering, a search around told me it could be a battery problem and it seemed to behave when I switched in my old battery (which I had thought to be dead but trickle charged a few days ago to check), only lasted for about 5 minutes before it started stuttering again but the battery is over 20 years old, chances are it won't hold a charge for much longer than that.

 

There are some idiosyncrasies I could do with clearing up; according to the instructions, upon installing the ESC it automatically calibrates, this is evident by an LED on the unit flashing, which it does, but it always flashes, I have left it for a few minutes and it never stops which makes it sound like it hasn't calibrated, the speed control on it is excellent though especially at lower speeds which was the problem with the old mechanical arm one I had, I did also try tweaking the trim so it was right in the centre of when it isn't making a noise but no change. The other thing is the sound, at first I thought it was fro the ESC but on closer inspection it is actually the motor which makes a high pitched buzz which sounds almost like an electrical alarm, is this normal? It happens on both my old (stock) 380 silver can and my new traxxas titan 380, its only at lower speeds though. On the operation side of things it doesn't seem to push straight in to reverse and is a bit slow in this regard, I heard that for some units this is a deliberate thing whereby a reverse motion after accelerating breaks and resets to neutral and a second reverse motion kicks in to reverse, is this what is happening on this ESC?

 

Other than those points I'm happy with it, very neat little unit, operates very smoothly and has a tiny footprint in the car.

Edited August 22, 2014 by elfergos