SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Oct 11, 2012, 02:10 PM
RC Geek
Scott_NJ's Avatar
United States, NJ, Stanhope
Joined Dec 2004
813 Posts
Discussion
Help me figure something out, anyone used a servo driver to control an ESC?

Hey guys, bit of an odd question and thought someone here might be able to help. I'm modifying a power wheels ride on toy and looking to replace the on off switch for power with a car esc.

The motors are not brushless and I think a pretty stock mabuchi style 540???

My thought is to use a brused ESC connected to a servo driver and then replace the dial on the servo driver with a horn of some kind linked to the gas pedal in the car.

Anyone know if this will work, and can anyone suggest what ESC might work? I would be powering with 3 6V sealed power supply batteries in series, so 18V, and then its driving two motors with a Y connector. I expect the AMPS to be in the 30-40 range max.

-Scott
Scott_NJ is offline Find More Posts by Scott_NJ
Reply With Quote
Sign up now
to remove ads between posts
Old Oct 11, 2012, 02:20 PM
Registered User
wparsons's Avatar
Canada, ON, Whitby
Joined Aug 2008
8,899 Posts
Any servo tester should work, as for ESC I'm not sure what would handle the voltage and load.
wparsons is offline Find More Posts by wparsons
Reply With Quote
Old Oct 11, 2012, 03:45 PM
Obeying the law of gravity
Jeremy Kamutzki's Avatar
Canada, ON, Cambridge
Joined Jul 2011
494 Posts
there's this
http://www.ebay.com/itm/Motor-Speed-...item1e6c4c52bf

but you'd need a separate BEC because input voltage is only up to 17v. I just googled 50A brushed car esc and got lots of results.
Jeremy Kamutzki is offline Find More Posts by Jeremy Kamutzki
Reply With Quote
Old Oct 11, 2012, 06:45 PM
RC Geek
Scott_NJ's Avatar
United States, NJ, Stanhope
Joined Dec 2004
813 Posts
Jeremy thanks, yea something like that would work I think. I am thinking if I can make up a control horn on the pot, then I can mod it for a second pedal. Gas from neutral forward, and then a brake / reverse pedal to the other side of the horn to put brakes on and back up.

As for voltage, since I am feeding really with three 6V's, I can just tap off two of them for 12V input into the ESC.

Any reason a servo tester should drive the ESC?

And thanks guys!
Scott_NJ is offline Find More Posts by Scott_NJ
Reply With Quote
Old Oct 11, 2012, 08:23 PM
Registered User
wparsons's Avatar
Canada, ON, Whitby
Joined Aug 2008
8,899 Posts
What pot are you planning on hooking up a control horn to?

A servo tester sends the signal to the servo to make it move just like a receiver would. An ESC runs off that exact same signal, so a servo tester will do the same thing with an ESC.

I'm a little confused by how you plan to power it with three 6v packs, but only put two of them into the ESC? If you want to run 18v, all 18v need to go through the ESC. You can't send half the power through the ESC and just add in more between the ESC and motor.
wparsons is offline Find More Posts by wparsons
Reply With Quote
Old Oct 12, 2012, 08:46 AM
RC Geek
Scott_NJ's Avatar
United States, NJ, Stanhope
Joined Dec 2004
813 Posts
WParson, a servo controller uses a potentiometer to let you travel the servo that is hooked up to it. So it sits at neutral and then you can cycle it left or right.

My thought is in theory on an ESC you can sit at neutral and then cycle towards forward, and then towards brake / reverse. Instead of turning that pot by hand, I would try to hard mount it below the pedal. I probably need to rig up some sort of spring on it though like the old servo keepers to make sure that if my kid jumps on both pedals it doesnt just tear the thing out of its mount.

As for the voltage, I see what you are saying, I was thinking I could run all 18 into the power side of the ESC, but use 12V to power the servo tester instead of the output from the BEC circuit in the ESC. That might not work though...


Quote:
Originally Posted by wparsons View Post
What pot are you planning on hooking up a control horn to?

A servo tester sends the signal to the servo to make it move just like a receiver would. An ESC runs off that exact same signal, so a servo tester will do the same thing with an ESC.

I'm a little confused by how you plan to power it with three 6v packs, but only put two of them into the ESC? If you want to run 18v, all 18v need to go through the ESC. You can't send half the power through the ESC and just add in more between the ESC and motor.
Scott_NJ is offline Find More Posts by Scott_NJ
Reply With Quote
Old Oct 12, 2012, 03:27 PM
Registered User
wparsons's Avatar
Canada, ON, Whitby
Joined Aug 2008
8,899 Posts
If the ESC can't handle the full 18v, it'll blow regardless of how you're powering the servo tester.

I was confused about the pot because it sounded like you were asking why to use a servo tester at all. I'm thinking something like a flexible pushrod from the pedal to the horn on the pot could work. That way if they jump on both pedals the cable will flex instead of braking anything off of mounts. You'll also need to "connect" it to the horn in such a way that turning the other way doesn't push the opposite pedal further out (kinda like the brakes/carb linkage on a nitro car)

How do you plan to handle reverse? Having a kid hit the brakes, then hit them again and go in reverse could give them quite the shock if they were just hoping to stay stopped.
wparsons is offline Find More Posts by wparsons
Reply With Quote
Old Oct 24, 2012, 07:33 AM
RC Geek
Scott_NJ's Avatar
United States, NJ, Stanhope
Joined Dec 2004
813 Posts
WParsons, thanks for the response, flexible cable like used on the planes could be a great idea to drive the servo tester, that way I can also mount it wherever I want.

On the reverse, that is a good question. The basic set-up of these cars uses a switch to change polarity on the motors so they stop, and then switch into reverse. It might be easier to keep that set-up and just use an ESC set up to apply brakes when you let off the gas.

Scott
Scott_NJ is offline Find More Posts by Scott_NJ
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Using old servo control boards as actuator driver/motor ESC for PROPORTIONAL control EQMOD Electric Power Cars 12 Dec 20, 2012 09:05 AM
Discussion Help me pick out motor, ESC, battery, and servos for my first scratchbuilt. MightyRed Foamies (Scratchbuilt) 4 Jun 19, 2012 09:42 PM
Discussion I need some help figuring out how to wire something up to my Rx asd9000 Radios 4 May 11, 2012 08:57 PM
Discussion recived an intresting pack today...help me figure it out eran_k Batteries and Chargers 3 Apr 04, 2006 04:31 AM
Can anyone help me figure this out... av8ersteve Batteries and Chargers 3 Aug 10, 2005 07:36 AM