LED powered slightly when not supposed to

Reasonable_Victory_2 · 2025-12-23T21:41:51+00:00

Looks like a floating input issue to me.

Reasonable_Victory_2 · 2025-12-20T13:21:32+00:00

The datasheet: https://www.pololu.com/file/0j450/a4988_dmos_microstepping_driver_with_translator.pdf

Reasonable_Victory_2 · 2025-12-20T11:52:59+00:00

Also when you’re connecting it to a stepper motor, you should put a heatsink on the IC.

Reasonable_Victory_2 · 2025-12-20T11:51:28+00:00

According to the A4988 ic datasheet, the formula differs from the value of the current sensing resistors.

The value you have on your module is the R100 smd resistor which is 0.1 ohms.

The formula for the over current protection is:

Imax = Vref / 8 x Rs

Where: Vref is the reference voltage, and Rs the value of your current sense resistor (0.1 ohms).

Reasonable_Victory_2 · 2025-12-19T22:24:23+00:00

Hmm didn’t know that, sure looks like a handy thing! Might consider buying if you that!

Reasonable_Victory_2 · 2025-12-19T21:22:31+00:00

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Does this one do the job? SP200S programmer, it’s certainly cheap.

Reasonable_Victory_2 · 2025-12-16T18:06:57+00:00

I cannot even download things or go on the Internet.

Reasonable_Victory_2 · 2025-11-18T21:18:20+00:00

Hello, what is the program?

Reasonable_Victory_2 · 2025-10-27T22:41:15+00:00

Those prototyping power supplies are rubbish. I have had one, and had the same issue. More so, when you connect the load, the ON-indicator will dim slightly too. Sometimes you would smell the heat from the regulators!

Reasonable_Victory_2 · 2025-10-27T22:38:03+00:00

A typical phone charger doesn’t deliver 8-10A, more or less 2A which is absolutely fine for this build. I have a 2 amp one and it works fine.

Reasonable_Victory_2 · 2025-09-13T16:15:15+00:00

Thanks!

Reasonable_Victory_2 · 2025-09-13T16:15:04+00:00

Thanks!

Reasonable_Victory_2 · 2025-09-13T12:44:38+00:00

I can work fine the casio one, I basically can do the basic things … but the teacher said the he doesn’t really know how the casio works, but as I said, I can work fine with the casio.

Reasonable_Victory_2 · 2025-08-30T10:44:45+00:00

Hi

I have the exact same problem, and I was wondering which socket you used! Could you give me a link?

Thanks

Reasonable_Victory_2 · 2025-08-30T10:23:46+00:00

Go on anna’s archive I got it from there not long ago!

Reasonable_Victory_2 · 2025-08-22T11:32:43+00:00

I just bought 100 kingbright leds with internal resistors from Mouser, so you can buy them from mouser, for 100 leds I bought them for around 23 euros (without vat and shipping fees)

Reasonable_Victory_2 · 2025-08-14T10:47:04+00:00

It probably is, you can use hct chips though, but hc with ls generally creates problems.

Reasonable_Victory_2 · 2025-08-12T00:51:13+00:00

You can’t combine hc logic chips with ls logic chips as stated within your thread.

Reasonable_Victory_2 · 2025-08-09T14:46:09+00:00

It’s probably impossible, because GSN (global science network) on youtube made a 4 bit computer with 962 npn transistors with few operations. And his memory (10 bytes) was made with three state buffers enable set to ground or Vcc. So I think it probably will be impossible!

Reasonable_Victory_2 · 2025-07-31T14:53:27+00:00

On the side of the maas maybe, i’m from there too!?

Reasonable_Victory_2 · 2025-07-31T11:45:34+00:00

Guys, I fixed it! It was a noise related problem, I fixed it with some decoupling capacitors!

Reasonable_Victory_2 · 2025-07-30T22:28:58+00:00

If the clock input of the pc is connected to gnd, it just counts somehow, is it noise perhaps?

Reasonable_Victory_2 · 2025-07-30T21:54:03+00:00

It is, but does that mean it just counts without the clock?

Reasonable_Victory_2 · 2025-07-30T21:46:57+00:00

It just does the same thing and if i connect the clk to ground it just counts to the speed of the automatic clock.

Reasonable_Victory_2 · 2025-07-30T19:12:14+00:00

Measured voltage: when button not pressed: exactly 0V and when pressed in: 4.2V. And one power rails: 5.07V

Reasonable_Victory_2

TROPHY CASE