user2899444

Quick question, or at least I hope so. When you have an electromagnet with an air coil would having an extremely tiny air coil diameter relative to the electromagnet's volume weaken the electromagnet strength? (Example: a 1inx1inx1in electromagnet with a 3mm diameter aircoil versus a bigger air coil).

@JonRB I wanted to confirm my understanding on something. You had mentioned PWM frequency and inductance. I figure I find the inductance of the electromagnet but the PWM frequency is determined by f = 1/(2*pi(LC)^0.5), correct?

@JonRB I wanted to confirm my understanding on something. You had mentioned PWM frequency and inductance. I figure I find the inductance of the electromagnet but the PWM frequency is determined by f = 1/(2*pi(LC)^0.5), correct?

ok! Thank you so much!

@JonRB So I would have to be careful not to have over 1A specifically to the output pins, correct?

@JonRB Thank you so much! It seems like the 'absolute maximum current' rating that both transistors can handle (datasheet 9.3.1) is 1 amp continuous but 2 amps would be at critical levels.

@JonRB oh! Voltage at the output is also Vcc2 (looking at 9.3.1 on the data sheet). Current flows from Vcc2 to Output, but the load amperage is contingent on ohm's law.

@JonRB, if I don't use PWM on any of the input pins and connect Vcc2 to a 12V DC power supply, what would the current be at my input (A) and output (Y) pins?

I'm watching a video to understand that part.

What to do with the current rise value?

Or does it matter as long as the arduino could detect the voltage at the output pins?

Is there a way I could determine inductance of my electromagnets since it seems important in this case?

Okay at arduino part.

I'm using a DC supply.

Wait, is this in the case of an AC supply? What if I'm using a 12V DC?

Oh, I think I get what you mean. You mean in my arduino code or whatever I need to inspect the voltage at pins 1Y through 4Y.

instead of a 555

I could get arduino to do the PWM at those pins, right?

I'll look up hystersis control.

The duty cycle at pin 2A would then determine the current at the output 2Y?

If let's say 1A is low and 2A is high (arduino setting), the circuit should PWM at 2A and do no PWM at 1A?

I was letting that sink in... Let me see if I get it, I put the PWM at the input pins (1A, 2A, 3A, 4A) and the pwm/current at the input pins will be seen at the output pins 1Y-4Y.

Is the PWM at Vcc2? or rather the output pins?

How do you determine the PWM and current?

I'm using the Arduino to change the logic/direction.

I'm trying to do something like this: www.e-alexander.net/magic_slippers.php

I need it to repel/attract and also stop.

I need it to go in both directions, yeah.

I'm a beginner.

Oh, I tried doing a BJT h-bridge and one of my transistors overheated. Then I was told that it's hard to find proper h-bridge schematics... I don't really know what I need to do.

I'm not too sure, but here's what I think I understand: In order to have a 0.5A output (or my desired current at the output) I need to use PWM at vcc2, best achieved with a 555, yeah?

3.0V because I thought the 1A would mess up the chip.

I was originally using a 3.0V that was giving 0.85A current even though I know that's well over the recommended minimum. I actually want to use a 12V power supply.

I'm not sure about inductance and getting those values.

They're hand-wound electromagnets. The resistance is small like 5 Ohms.

I really want to have a 0.5~0.7A current going through the electromagnets.

Okay, I see on the datasheet it recommends a 0.1uF capacitor at Vcc1 and Vcc2, is this what you're talking about when you mention decoupling capacitors?

@JonRB Okay. I want to better understand how the current value at the output pins are determined and the max current this IC could take.

Hi everyone, could someone help me understand how to read the sn754410 datasheet (ti.com/lit/ds/symlink/sn754410.pdf) At the absolute maximum rating section (7.1) it mentions Ip (Peak output current) and Io (Continous output current). I want to understand if the power source that Vcc2 is connected to provide a current of 1A would also mean that Io = 1A? Does the current at Vcc2 affect the peak output current and/or continuous output current?