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I'm trying to test my 20A Hobbywing Skywalker electronic speed control (ESC.)

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For that I bought this servo tester from eBay.

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I'm a bit confused about the servo tester input. Shouldn't it be just supply power? What is that third pin (signal) on the input side?

Can I check the ESC without supplying it with power and connecting a motor?

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    \$\begingroup\$ If you do not supply the ESC with power, what would you be testing? The circuitry would require power for it to perform in any particular way. \$\endgroup\$ Commented Oct 30, 2012 at 6:25
  • \$\begingroup\$ @AnindoGhosh Thought there will be some indicators (like LEDs, beeps...) to indicate the status of the ESC.. Then i won't have to bother every time to connect batteries and motors.. Anyway, thanks for the info! \$\endgroup\$
    – Anubis
    Commented Oct 30, 2012 at 6:36

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I have the same servo tester: The input does require just the supply voltage to be provided. The PCB trace for the S pin is not connected to anything else on the circuit board.

It appears that the 3-pin connector has been used by the designer to accommodate customers whose only source of a 4.8-6 volt supply is a servo connector from either a battery pack or some other servo control equipment.

The third pin does provide improved structural stability compared to a 2-pin connector which would be prone to shear or lose grip due to accidental pulls on the wires, or rough use. However, I would hesitate to state that this was one of the thought-through reasons for the design decision.

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  • \$\begingroup\$ Can't i use a regular power supply unit to power up the motors (instead of 11.1v LiPos) ?? \$\endgroup\$
    – Anubis
    Commented Nov 1, 2012 at 7:40
  • \$\begingroup\$ Sure you can - if your power supply can deliver 11 volts clean DC at the high current that LiPo batteries support. Keep in mind that the battery can support a very large initial surge current, while most "regular" power supplies cannot. \$\endgroup\$ Commented Nov 1, 2012 at 8:08
  • \$\begingroup\$ You mean i must supply exactly 11.1v?? but my power pack is capable of providing multiples of 3v! can't i do it with 12v? (that's the max). I tried doing so but it's not working as it should. Initially when the power pack is turned on, it plays "123" lind of tone. Then it waits for about 5 secs and start to "beep" continuously, (nearly) once a second.. \$\endgroup\$
    – Anubis
    Commented Nov 1, 2012 at 8:24
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    \$\begingroup\$ For one thing, supplying more than the rated voltage runs the risk of frying your motors / controller, though 12 volt might not be that bad. For another, the beeps, if they're coming from the power supply, most likely indicate an over-current alarm. In other words, your power supply cannot cope with the demands of the ESC and motors. An assumption behind all this is that you have checked the polarity of the supply and aren't feeding it in reversed. \$\endgroup\$ Commented Nov 1, 2012 at 9:10
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    \$\begingroup\$ If it works through servo pulses generated by your microcontroller, it would work the same via the servo controller. All the servo controller does is pass the + and ground lines though, and inject servo pulses on the S line, pretty much like you have done with your Arduino. \$\endgroup\$ Commented Nov 1, 2012 at 9:17

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