I am planning on making a mechanical 7 segments display where each segment is power by a servo motor turning them on and off by rotation. I am wondering if I connect all of those components (2 pca9685 - each have 14 sg90, 1 arduino nano) to a 5v external power adaptor, how many amps does the adaptor needs? and is 5v enough? If anyone could provided a link for the correct power adaptor I should use for this project I would be appreciated.
Thank you all.
What is the stall current of 1 sg90 at 5V? How many of the 28 might be moving at the same time?
How many digits will the display have ?
If you activated all 28 servos at the same time, I suggest you use a 5V, 20A supply for the servos and a separate 5V 1A supply for the Nano
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5V is enough, Amps are cumulative so just add the max amps from each device (stall current for the servos) That gives you worst case, after that it takes human imagination.
Interesting project. So 1 servo controls 1 segment of one display. It sounds like a four digit display so I guess absolute speed is not so important and you can stagger the changeover of the segments, maybe giving some priority to the lower digits. That is you avoid powering all servos simultaneously. If it is a 24H clock, the worst case is the rollover from 11:59 to 00:00 (13 segments are changed). If it is a counter, the worst case is the rollover from 9999 to 0000 (8 segments are changed).
An old ATX PSU gives plenty of amps @ 5 V.
We will know more if @thunder200911133 every replies but until then we know virtually nothing
Well, we can already make a reasonable guess from the information supplied, at least about the number of digits:
You are right. I missed that
It will have 4 digits, 2 for the hours, 2 for the minutes
This is the design I am following
Original link: How to build a mechanical 7 segment display clock | DeepSea
I will be using an arduino nano instead of the ESP32 DEVKIT.
Although there are only 2 servo, but the final product will have 28 servo evenly divided by 2 pca9685.
I don't know what change "at the same time" means, since I will be using a for loops to change each segments of each digits, so there will be a bit of delay between each segments because of the for loops. But I don't know if that counts as change at the same time.
Cool, I hope it will be the same experience as of these old boards at train stations.
If you start one servo then immediately start the next servo and wait for the first servo to finish before you start the third servo and so on, then you only need a 5V 2A supply. However I would connect a 470uF capacitor to each of the PCA9685 boards and a 100uf to the ESP.
You might as well get a slightly bigger supply just in case you decide to add something like LEDs and buzzers.
Ok thanks.
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