Arduino smart blinds with tower pro servos mg996R

Projects General Guidance
1

I have 6 blinds I'd like to control with the Google assistant via voice commands. I purchased a raspberry pi 3 that I plan to use as a hub in my house. The pi will run openhabian as its OS. I want to be able to control each blind individually, in sets of 3 for each room, control a percentage of open/close, and possibly set schedules. There are several YouTube videos on this, but my application will be a little different I'm sure. I don't have any experience with this, so when it comes to actually programming this stuff I'm sure I'll have a lot of questions.

I saw a YT video where a guy can contol several servos off one Arduino uno and another board.

https ://youtu.be/QjX4JKU_I9M

From my understanding he directly powers the other board featured in the video with a single 5v 2A power source. This powers the servos directly from the board and then the Arduino is powered off this accompanying board too. Is this correct? Is this a smart setup? It would save me from buying two power sources, a power strip to plug them into my outlet, and 2 additional Arduino boards. Which, by the way, this is the cheapo ebay board I was looking at. It has the esp822 (I think that's the number) wifi module already installed. It has a micro USB programming port on it, so I can program with an old phone charger cable

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F122876108499

Next question; has anyone cut into a power supply cable like this one from Amazon to lengrhen it?

[2 PACK] BOLWEO AC 100-240V to DC 5V 2A Power Supply Adapter, 10W Adapter for TV Box, LED Strip Lights ,Audio/Video, Wireless Router,DC Connector Jack 5.5mmx2.1mm

I'm not sure if I could stand to lose any voltage over the increased length though. I'd like to have a 15'-17' cable. If I can't lengthen the cable on the power source I guess I'll have to run an ugly extension cord around the side of the window and hide the power source box and extension cord in the blind reacway somehow. If I have to do this, it'd be even better if I could only use 1 Arduino to eliminate power sources and extension cords.

What's the best way to power the Arduino and the servos? Can I power the servo right off the Arduino 5v? How can I best power 3 servos off one Arduino? Solutions need to be coming off 120v. These are blinds in my house that I'll be using every day and worrying about batteries will not be an option.

2

Welcome to the forum.

please read 'how to use this forum' on tips.
it is a sticky post on the top of every forum. especially note #7

as for your first post.
getting rid of all the un-neeeded text, it looks like you have two questions.

#1) can you power from a 5v power supply salvaged from old phone

YES

#2) power , what is the best way ?

you will need sufficient power at each MOTOR. you are powering the motor with the needed power. your signals are low power so are secondary.

running power wires inside of walls is bit of a challenge, but will look the best.

AC is much better for distance than DC due to wire resistance.
I would run the wires on the surface to get the parts in and working and make it work the way I wanted, then consider how to hide the wires. each window location might offer different options.

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dave-in-nj:
Welcome to the forum.

please read 'how to use this forum' on tips.
it is a sticky post on the top of every forum. especially note #7

as for your first post.
getting rid of all the un-neeeded text, it looks like you have two questions.

#1) can you power from a 5v power supply salvaged from old phone

YES

#2) power , what is the best way ?

you will need sufficient power at each MOTOR. you are powering the motor with the needed power. your signals are low power so are secondary.

running power wires inside of walls is bit of a challenge, but will look the best.

AC is much better for distance than DC due to wire resistance.
I would run the wires on the surface to get the parts in and working and make it work the way I wanted, then consider how to hide the wires. each window location might offer different options.

Thanks so much for the reply! I did read the "please read" stickies. I'll keep it shorter if that's what everyone needs. I like to be detailed too though.

Thanks for.answering question 1. I'll run an extension cord (AC) up the wall behind a curtain and have the 5v power adapter hidden somewhere. I will NOT be running wires on walls. In the bedroom I will be removing some trim and hiding wires behind it.

#2: still not sure I'm understanding the answer and best method. If I'm going to power 3 motors from the board outlined in the YT video I linked do I still only needed a 5v 2a power adpater or does the adapter need to put of 15v 6a?

If I program the board so that the motors never run simultaneously will the 5v 2a power adapter work?

#3 is there anything wrong with the ebay Arduino uno wifi board I linked to?

4

Looks like this might be a better power supply to get me on the high end of the output torque the servos are capable of.

OMNIHIL Replacement AC / DC Adapter Charger Cord 6V 2A (2000mA) 5.5mm x 2.1mm Regula... https://www.amazon.com/dp/B00LU8Z9JI/ref=cm_sw_r_sms_c_api_Lr2WAb8CXGRR4

5

Schroeder1:
Looks like this might be a better power supply to get me on the high end of the output torque the servos are capable of.

OMNIHIL Replacement AC / DC Adapter Charger Cord 6V 2A (2000mA) 5.5mm x 2.1mm Regula... Amazon.com

If I do use this adapter and power the Arduino through the barrel connector how should I power the 3 servos from the board? Do I need to get something like a bread board to leave in the blinds to split the power?

6

Can anyone comment as to whether the linked eBay Arduino uno wifi board is a good selection and also please direct me how to power the Arduino and the 3 servos with one power source?

7

For wifi connections do look at the NodeMCU and WeMOS boards as well. Often a more convenient solution.

An Uno is great for development work, not for permanent projects as you can't easily solder connections to it. Jumper wires will work themselves loose over time.

8

wvmarle:
For wifi connections do look at the NodeMCU and WeMOS boards as well. Often a more convenient solution.

An Uno is great for development work, not for permanent projects as you can't easily solder connections to it. Jumper wires will work themselves loose over time.

Thanks a lot for your helpful reply. Is this the board you are recommending?

https://www.amazon.com/dp/B01IK9GEQG/ref=cm_sw_r_cp_apa_g3FXAbET9WZFJ

Is this the wemos board you'd recommend?

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F331998793323

I see that the nodemcu takes a micro USB for power only. How do I go about powering the servos off it? I have read from various sources that servos should not be directly powered off boards like this because the micro USB cannot deliver enough voltage and amperage. Is this true? If I use this board do I have to get a wall power adapter and cut the barrel and off of it to directly feed the servos? Can one wall adapter feed 3 servos in this manner? It looks like the typical wall power source delivers 5 bolts at 2 amps. With this method only the signal wire would go to the board?

The wemos looks like it has a Barrel Port for a wall adapter. This would give me more current and voltage. With this board would I power it directly with the wall adapter and then run wires to power ground and signal to the 3 servos directly off the board?

Again, most of my questions right now lie around how I power the board and how I power the servos. Right now I'm under the assumption that power for the servo, much less three, can not come directly off the board and will require a separate power source of some sort. I would love for this to not be true! In a perfect world I would run a barrel Style 5 Volt 2 amp power source directly to the board and off of it run wires to the three servos to power them.
Right now my question is basically how do I do this and which components do I need.

9

The WeMOS D1 is a terrible attempt at making an Arduino clone. Get the WeMOS mini.

I see that the nodemcu takes a micro USB for power only. How do I go about powering the servos off it?

It should perfectly happy taking 12V on the Vin pin. Just like the WeMOS. Servos are to be powered separately, as always. The regulator on the board can't handle motors of any kind.

Do keep in mind that this are 3.3V boards, not 5V like the Arduino. That means that you can connect most sensors without level shifters, but also that some servos may not work (if 3.3V is too low a level for them). Also your MOSFETs need lower VGS(th), many logic level MOSFETs do not open well at 3.3V.

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wvmarle:
The WeMOS D1 is a terrible attempt at making an Arduino clone. Get the WeMOS mini

Do keep in mind that this are 3.3V boards, not 5V like the Arduino. That means that you can connect most sensors without level shifters, but also that some servos may not work (if 3.3V is too low a level for them). Also your MOSFETs need lower VGS(th), many logic level MOSFETs do not open well at 3.3V.

Thanks for the suggestion on the mini. All the videos on YT that do stuff like this are all development type projects. They aren't real life projects. Morning smart house may have one where he shows how to power everything with his kit. I'll take a closer look at that. Every other video has the power coming off the board on a bread board though.

What components do I need to power the board and the servos? Right now I'm planning on running the mini USB cable to the board and then running the 6-7volt 2a power supply right to the servo with it's signal wire and ground going back to the board. Does the 7v 2a power source get grounded on the board too? Do I need capacitors etc? Will this work?

11

You need to connect the grounds, overall this sounds like a good arrangement. Make sure the servos don't take more power than your power supply can deliver (check the ratings).