74LS125 is a quad- tristate buffer. I am using it for turning on and of the connections between servo and my servo controller for irrelevant reasons. Note that that IC is low-active so when the enable pin is connected to ground, it is allowing current to pass.
Anyway, I am positive that two servo pwm signals are intertwining with each other. Sometimes, not always, servo 2 moves when I am moving only servo 1. I really want to prevent that.
Some other information:
I am prototyping using a breadboard.
I am using single core assembly cable for connections and yes those cables are pretty located close but isolated by rubber cover.
I am using standard jumper cables for external connections.
Of course pin 7 is grounded. I didn't draw it to complicate the diagram. As you may have well understood from my question, I am not having trouble using the IC. I will draw more accurately next time.
Inadequate servo power supplies, such as misguided attempts to use the Arduino 5V output, account for at least 95% of the servo problems reported on this forum.
Post ALL the details of your setup, not just those that you think are relevant. Include the specs of the Arduino and servo power supplies, and show all ground connections.
What do you think the 74LS125 does in your circuit, and what is it supposed to do?
I suspect that "parasitic" is meant, and that capacitance between connecting wires, breadboard tracks, etc. is the only reason that the circuit even seems to work.
jremington:
I suspect that "parasitic" is meant, and that capacitance between connecting wires, breadboard tracks, etc. is the only reason that the circuit even seems to work.
Otherwise, the circuit makes no sense to me.
To me, it looks like an attempt to switch the servo ground on and off. It should work for really low currents but I guess a servo load is usually too much. That is a huge assumption as the connection at the servo is not labeled.
Yes, the problem was not parasitics. It was a power problem. Which raises the question of how can it be solved.
I connected just one servo to an external 5V adaptor and it worked fine. However, to the best of my observations, when I use multiple servos or use one extensively; voltage readings decrease all the way up to 4V. I tried using ardunio's 5v, external adaptor and some batteries but the result is the same.
This is just one part of my circuit, there are some other parts vital for me that I can let these type of voltage dropdowns. Is there a way to regulate and achieve a stable 5V supply.
I am using 125 to manage servo signals, not their power input.
My servo is sg90. I will have 4 of them on board. In this case, will 7805 voltage regulator be enough which supports up to 1 v according to its datasheet. I have a 11.7V lipo battery which will support power to the whole circuit
