Easiest way to control 3x servos, 2x 12VDC fans, and 2-3x TECs?

So quick breakdown of the project is I want to control the following with a 0-5V input signal to the Arduino:

  • 3x servo motors
  • 2x 12VDC fans
  • 2x or 3x thermoelectric coolers

After doing some research, it sounds like an Arduino Uno would be the best route, with POTENTIALLY one motor shield.

Now motor shields appear to have the option to control two fans and two servos simultaneously. I need three servos, but two of them operate in reverse of one another (i.e. they both go between 0 and 90 degrees, with one at 0 and other at 90, or one at 15 and the other at 75, both at 45, etc etc). I would think I could use a Y splitter and reverse the polarity on each so they would operate on one output of the shield, meaning I could control all three servos from two outputs. Does that make sense, or are these just the crazy ramblings of a mechanical engineer?

Now if the above DOES work, then I still have 2-3 TECs to figure out how to control. Does getting one motor shield AND an additional add on make sense for all this, or is there some more efficient way of doing everything here?

Please post a link to those servo and a wiring diagram telling what signal You intend to reverse, and links to the motors and coolers in order to size the drivers needed.

Three servos are easily controlled by any Arduino board, but if you are hoping to power them through the USB or 5V pin, you may run into issues. They will likely exceed the current capability of the Arduino. You can instead supply 5V from an outside source (I use 18650 batteries regulated to 5V by a buck converter, this can also power your Arduino). For a 12VDC fan, you will need either a bipolar junction transistor (BJT) or a MOSFET. This will depend on the current requirements - you will quickly exceed what a BJT can handle, but they are cheaper. To turn on the fan, you power the base of the BJT/MOSFET (for npn BJTs, stop powering for pnp BJTs), which then allows 12V at the collector to flow out the emitter (some math here to get actual voltages). I'm not sure how your TECs work without more info.

Personally, I create my own shields using a CNC machine so I can get exactly what I want - especially when it's an obscure application like whatever you're doing here.

Railroader:
Please post a link to those servo and a wiring diagram telling what signal You intend to reverse, and links to the motors and coolers in order to size the drivers needed.

I'm not 100% certain on the parts yet, but they should be pretty close to these:
Servos: https://media.digikey.com/pdf/Data%20Sheets/Adafruit%20PDFs/169_Web.pdf
Fans (B044): https://media.digikey.com/pdf/Data%20Sheets/NMB-MAT/bg0903.pdf
TECs: https://www.digikey.ca/en/products/detail/wakefield-vette/TEC-30-39-71/9741965

Looking at how servos are wired, it doesn't look like you can simply flip the connector as the PWM would get hooked up to the negative line in that case, but would something like this work:

They just switch the pins the +/- wires are attached to in the connector. That's what I was hoping I could do to reverse the direction vs. using another shield.

Rl4ndom:
Three servos are easily controlled by any Arduino board, but if you are hoping to power them through the USB or 5V pin, you may run into issues. They will likely exceed the current capability of the Arduino. You can instead supply 5V from an outside source (I use 18650 batteries regulated to 5V by a buck converter, this can also power your Arduino). For a 12VDC fan, you will need either a bipolar junction transistor (BJT) or a MOSFET. This will depend on the current requirements - you will quickly exceed what a BJT can handle, but they are cheaper. To turn on the fan, you power the base of the BJT/MOSFET (for npn BJTs, stop powering for pnp BJTs), which then allows 12V at the collector to flow out the emitter (some math here to get actual voltages). I'm not sure how your TECs work without more info.

Personally, I create my own shields using a CNC machine so I can get exactly what I want - especially when it's an obscure application like whatever you're doing here.

Oddly enough I did just build a CNC in my basement. That said, I think just using off the shelf parts would be the easiest way to get started right now, but definitely something to consider once I get my feet wet in some more electrical oriented projects.

In terms of power supplies, it SOUNDS like I can hook a 12V supply up to the Arduino if I remove (or add...can't remember) the jumper to the 5V regulator on the board (or maybe I'm think of the Nano). I have no problem adding a separate power supply, if necessary. I'll need something for the TECs either way, but may a few to split things up between TECs, fans, and servos. This all started off as a concept in my mind and I'm still trying to flesh out all the details, so my electrical knowledge isn't quite there yet.

Why do you want to provide the Arduino with 12V? You could do so and use the same supply for your fans but don't make the mistake of thinking that the Arduino can provide power to any of the components you want controlled.

The TECs and the fan needs drivers. It can be done using logic N channel MOSFET transistors. Note that the TECs are rated 3 Amp at 12 volt.
Those servo contain electronics that surely will be sad and maybe send smoke signals if + and - are reversed.

wildbill:
Why do you want to provide the Arduino with 12V? You could do so and use the same supply for your fans but don't make the mistake of thinking that the Arduino can provide power to any of the components you want controlled.

Can it not power the Arduino and the fans at the same time? This is more to limit the number of power supplies I'll need for the whole setup.

Railroader:
The TECs and the fan needs drivers. It can be done using logic N channel MOSFET transistors. Note that the TECs are rated 3 Amp at 12 volt.
Those servo contain electronics that surely will be sad and maybe send smoke signals if + and - are reversed.

The motor shield would serve as the driver for the fans, no? Presumably I would need a separate driver for the TECs, but could I use a 12V power supply with a higher current rating to supply everything at once?

You did not present a link to the motor shield You've got but the fan is not that very hungry for current so likely it will work without smoke.

@wildbill tells: don't consume any extra current out from the UNO board if You use the Vin and 12 volt.

Railroader:
You did not present a link to the motor shield You've got but the fan is not that very hungry for current so likely it will work without smoke.

@wildbill tells: don't consume any extra current out from the UNO board if You use the Vin and 12 volt.

Apologies, I was thinking of something like this:
Arduino Motor Shield V3: https://www.amazon.ca/Arduino-A000079-Motor-Shield-12V/dp/B0084ZQF3O/ref=sr_1_5?dchild=1&keywords=arduino+motor+shield&qid=1615573699&sr=8-5
or this
L298N Motor Driver: https://www.amazon.ca/PChero-2Packs-Controller-Stepper-Arduino/dp/B07C4B3DL4/ref=sr_1_5?dchild=1&keywords=l298n&qid=1615573715&sr=8-5

I feel that the simple L298N would do. Check max voltage and max current.
You tried but... The Amazon site is a sails site and engineering data is either absent or deeply hidden.

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