Simple servo control help

Projects General Guidance
1

Hi guys. First up, my apologies - this is really a basic electronics question rather than an Arduino one, but I figured you guys would definitely point me in the right direction.

I'm building a DRS (drag reduction system) for a racecar. It moves one plane of a multi-plane wing through a 60 degree angle. The movement needs to be quick (sub-0.5s) and needs to hold a force of around 30kg in its "up" position. Ideally, I want it triggered between the two positions via what are effectively two momentary switches (12v feeds from other on-board switches).

Having looked at pneumatic and hydraulic options, I'm now looked at electric actuation due to simplicity and weight considerations. My electronics skills, however are fairly rudimentary.

I'm proposing to use a pair of these:
https://www.amazon.co.uk/ZOSKAY-Torque-Crawler-Compatible-SAVOX-0236/dp/B0BTZ5FTXX

Now, as it's just a simple 2-position movement, I was hoping to avoid the complication of anything that needs full coding and instead just use a simple movement module like this:
https://kitronik.co.uk/products/2177-kitronik-movement-module-simple-servo-controller

However, 5v isn't going to cut it and fag packet sums say it's going to be potentially pulling 10A+ at full load.

So I'm thinking some NPN transistors wired in parallel plus a resistor to make a low side switch (this is about the limit of my electronics knowledge!)

So, questions:
Am I reinventing the wheel? Is there just an off-the-shelf module that will do this job (and likely be more reliable that my home-brew lash up)? Is this what a MOSFET switch/driver is?
Generally, am I on the right lines, and will these components suitably rated to work together?
Any links to specific components/products would be most appreciated too!

Thanks in advance for any help you can offer.

2

Hi, @nefarious1. You mention transistors a few times - just forget that idea. These servo motors are controlled only with a certain signal and have everything else built into them. However, this servo is quite powerful and runs on 12 volts and will not work on 5 volts. The selected servo and control board should work together, but only ground and the control signal should be connected, as the board is powered with 5 volts and the servo motor with 12 volts from a sufficiently powerful source.

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Thanks very much for the reply!

Wow - so this might be easier than I feared!

Just to clarify (because my understanding of the inner workings is pretty vague) - The servo has three wires. You're saying connect the signal and ground wires from the servo to the control board, but the positive to the 12v source. Where does the 12v ground go? Piggy back onto the 5v ground?

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Yes
Of course you also need 5V power for the controller board

5

Cool. Thanks.
It's all getting powered off the car battery (13.7-ish lithium race battery) and the alternator. The control board will get 5v via a step-down converter.

I knew you guys would be the right people to ask :slight_smile:

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And just to give you context - if this all works it should be worth between 3/4s and a second on a roughly 60 second lap. To achieve the same time gain with engine modifications would cost £4-5k, so this has been a big help :grinning:

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