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ESC? — Parallax Forums

ESC?

MatthewMatthew Posts: 200
edited 2004-10-28 01:05 in General Discussion
Can an ESC be used instead of a servo when connecting to the Parallax Servo Controller?

I'm looking at this ESC (Electronic Speed Controller):
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXUY13&P=0

And this servo controller:
http://www.parallax.com/detail.asp?product_id=28023

Thanks,
Matthew

Comments

  • Jonny555Jonny555 Posts: 46
    edited 2004-10-19 12:39
    Servos and ESC's work with the same range of pulse widths(~1-2ms). I chose an ESC for a brushless motor manufactured by castle creations(which I highly recommend). The ESC doesn't work due to a software problem(bought it on ebay). So after sending an email to CC they immediately sent out a replacement. Thats service!
    Wish my gps module manufacturer(Laipac) could offer such quick and professional service. (1 month waiting on a simple repair...)

    So, to sum up my thoughts, THEORETICALLY IT WILL WORK.
    I have yet to test it because i'm still waiting on canada post.
    In practice, you need to determine the exact values the ESC is expecting in terms of signal. This can and must be confirmed with the manufacturer so choose wisely.


    Now, how I set it up is simple.
    Lithium polymer powers ESC(with low voltage cutoff) and BS2(with its own low voltage cutoff). The BEC(battery elemination circuit) from the ESC powers the PSC.

    What i have to suggest as a final comment, is to purchase a Astroflight servo tester to make sure everything works proper(~25$ from tower hobbies) while not setup with the PSC. This is how I determined that it wasn't the PSC causing the problem, it was infact the ESC that was defective(wiped).

    Now that futaba you linked looks great, I am quite certain it will work, although i wouldn't be willing to bet the farm on it. Definately worth a shot. Keep in mind that you would need 2 power sources if using this controller. If you are like me and appreciate more "bang for your buck" you could get an ESC with BEC and have 1 power source. They call it BEC because traditionally electric R/C use a battery for the motor and another for the Receiver/servos.·It has become more and more popular for obvious reasons.



    Jon

    Post Edited (Jonny555) : 10/19/2004 1:19:07 PM GMT
  • sunktrucksunktruck Posts: 10
    edited 2004-10-26 19:16
    Yes you can add an ESC to your BS2. I have a Novak Super Rooster connected to a BS2p via a 555timer and a digital POT. Like Jonny555 states eveything will run off of a 7.2V nicad battery using BEC and a v-reg. I experenced BS2 resets everytime i tried to set the ESC to motion. Adding a large >1000uF cap on the regulated side of my 7805 fixed the problem. BTW i have old tired nicads, so that may be my issue as well. Good luck

    -Greg
  • MatthewMatthew Posts: 200
    edited 2004-10-27 00:43
    Could you give a quick drawing of your schematics?
    Thanks.
  • sunktrucksunktruck Posts: 10
    edited 2004-10-27 03:11
    Here is the schematic of the 555 timer circuit. http://members.cox.net/gregd262a/schem.gif

    The output of Q2 is tied to the white signal wire (for Futaba Servos and most ESC's), also connect a common ground between your BS2 supply and the black wire of the ESC. R15 is used to "center" the ESC and R16 is used to adjust the period (~17ms). U7 is used to control the speed of the ESC. Send a "0" to the digi pot and get full reverse and send "15" to the pot and get full forward. This is based on 1000us and 2000us pulse width, and adjusting R15 to 1500us when U7 is sent a "7". The drawback with this circuit is as the pulse width is adjusted, the period is adjusted. This is not really and issue since most servos/ESCs work well with a 10ms-25ms period. VCC is my regulated 5V supply

    I tested and adjusted this circuit with a servo using VCC for the servo's positive input (red wire)

    If you have any more questions, let me know
  • Armored CarsArmored Cars Posts: 172
    edited 2004-10-27 21:30
    I was planning on using an ESC with my BS2, can the white wire be connected directly to one pin and the pulsout command used instead of that circut? You also mentioned having the BS2 reset and if I understand you correctly reccomend putting a large capacitor between the ESC red wire and Vin.
  • sunktrucksunktruck Posts: 10
    edited 2004-10-28 01:05
    I would think that would work fine, however I would put a series resistor inline with the BS2 pin. I guess I should have stated the reason for my circuit, my appologies - I am using a WAIT parameter in a SERIN call that prevents me from using the PULSOUT command. Also my cap is between ground and the VCC pin of the BS2.
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