building a drum spinner

[Anttazz]

Re: building a drum spinner

I've never tried it personally on a sabertooth, but going by the specs 2 drills on 24v would be fine on a 2x25a ESC.

Fully charged 24v packs could be getting close to 30v though so might be tight in that sense.

[Max]

Re: building a drum spinner

Could I protect it with some kind of fuse?

[Max]

Re: building a drum spinner

.....Or a voltage regulator or a Zener diode? Has anyone used any of these devices/components before?

[typhoon_driver]

Re: building a drum spinner

The sabertooth is a nice controller but I have blown two in the past (they were replaced as I hadn't exceeded the specs but was at the limit).

I was running 2 18v drills on 24v worth of nicad cells. The interesting thing being, if I remember right is that the manual states that only 18 nimh/nicad cells should be used, well below 24v. I ran it with 20 cells. Initially the controller was fine but after a minute it blew (nothing beyond moving the robot around).

Stick religiously below the limits and it should be fine

[Max]

Re: building a drum spinner

Could I use a voltage regulator so that I only have 12v out of the 24v going to the drive system from the batteries but still have 24v going to the speed 900 motor to power the drum?

[typhoon_driver]

Re: building a drum spinner

No as the voltage regulator would have to handle huge current surges. The simplest way to do it is to set the travel on your transmitter to 50% on the two channels that are used for drive. This way the motor only ever effectively sees 12v. What transmitter are you using?

[Max]

Re: building a drum spinner

No as the voltage regulator would have to handle huge current surges. The simplest way to do it is to set the travel on your transmitter to 50% on the two channels that are used for drive. This way the motor only ever effectively sees 12v. What transmitter are you using?

i am using a dx6i transmitter, and i thought that the speed controler varied the current not the voltage to change the speed but i could be wrong? could i use a transformer imbetween the battries and the speed controler to turn the 24v into 18v? does this kind of transformer exist and would it be to heavy?

[typhoon_driver]

Re: building a drum spinner

all the speed controller does is turn on and off very quickly to control the motor.

http://www.4qdtec.com/pwm-01.html

To put it simply, no, no it doesn't exist. Hook up the speed controller to your batteries. Change the travel adjust on the transmitter to 50 percent for the two channels you use for drive on the transmitter and the motors will only effectively see an average voltage of 12v.

Please note, that you should still respect the maximum limits that the sabretooth states overall.

This is the simplest method to run your motors on a lower voltage by tricking them into seeing the lower voltage. I have used this method several times myself and it doesn't require additional weight or parts in the robot.

[Max]

Re: building a drum spinner

How do I limit the travel of the gimbals on the transmitter

[typhoon_driver]

Re: building a drum spinner

You don't. Check the manual for the transmitter and read the section on travel adjustment

[Max]

Re: building a drum spinner

How flat is the robo-challenge arena? Will 2-3mm ground clearance be enough? And how much do you think my new robo-challenge blue wheels will wear down?

[RogueTwoRobots]

Re: building a drum spinner

The RC arena floor is pretty damn flat, so much so that ground-scraping wedges or flipper blades very rarely get stuck on the joins. 2mm-3mm should be fine (particularly if your robot is 4WD, but 2WD will still cope comfortably).

The blue wheels are pretty tough too. They will wear down over time (and by how much depends on how much pushing your robot does and how often it runs) but you could be looking at as much as a couple of years use, if not more, before they get so worn down that your ground clearance becomes an issue.

[Thunder arrow]

Re: building a drum spinner

Where did you get the speed 900?

[Max]

Re: building a drum spinner

I got mine from Cornwall model boats

[jonny]

Re: building a drum spinner

you can get them from smc