Raspberry Pi Forums

Burngate

... So, I know that sometimes making things simple are not possible but I would like to keep it as simple as possible. Main questions are: 1. Can I use transistors to match my data line voltage to something close to 5V? 2. How can I drop my current from 5.3V to 4.7V, considering it might draw 60A? ...

Burngate

If you replaced the 12V DC supply with an AC supply, the only thing that wouldn't like AC would be the LED, and that could be cured by putting a diode across it in reverse.

Your relay board is pretty much the same as a shop-bought one

Burngate

You could replace the FET with an optoisolator.

Burngate

I don't think you need to change anything - you're using the Pi's 5v as the positive supply for the LEDs, so (5-1.8)v or (5-2.1)v across the LM3914. It should be quite happy with either.

Burngate

I do have a resistor, I just pulled out a random one at the time because I did not feel like doing the lookup to see what the resistance was. I'm going to bet the third ring was black. Brown or red would have been good. Orange very dim. Yellow, green, etc. and you'd think it wasn't working. https:/...

Burngate

Update: I just noted you did not indent the code after the while. To be in the block with while the code must be indented like my example. In other words the way your code is written the while statement will be in an infinite loop but the statements after it will never be executed! Actually he did ...

Burngate

Will using pulse width modulation save battery by decreasing the power consumption (on time) and still provide me with the same apparent brightness on video? I am assuming I will need to counter for flicker created by the video frame rate. Essentially, no. The camera has a rolling shutter - that is...

Burngate

If it worked once, then stopped working, you may have broken your Pi.

What code were you using, and how did you connect the LED?

Burngate

... , but I'm concerned about amperage. The alarm install guide says: "The panel can supply up to 1 amp (1000 mA) in full load alarm condition for system devices connected to panel." Rather than amperage you should be considering power, since the buck converter trades volts for amps. If the Pi were...

Burngate

In essence, a breadboard is just a set of wires; a PCB is also just a set of wires. How did you connect the Pi to the breadboard, and how are you connecting the Pi to the PCB? If in both cases you used a ribbon cable, have you got it the same way round? (There are four ways to connect it, only one i...

Burngate

Temperature sensors are available that can connect to the I2C bus, no hat necessary.

However, I'm not sure what EMF you want to to measure.
Lightning strikes? Mains current magnetic field?

Burngate

To see where the problem lies, it might be worth while replacing the flowmeter with a simple switch. If your Pi can recognise pulses from a switch and count them as "gallons", then the flowmeter isn't doing what you (and the rest of us) think it's doing. On the other hand, not seeing pulses means yo...

Burngate

jamesh wrote: ↑
Sat Jan 04, 2020 7:07 pm
9 year. 9 YEARS!!

So I'm just guessing here, but it appears obvious that jamesh in the process of setting up a degree course in the history of computerised necromancy.
Why else would he have hidden away several pertinent posts, instead of just locking the thread?

Burngate

ricbritain wrote: ↑
Sat Jan 04, 2020 12:39 am
***I can't attach the photos as they are the wrong file type!! JFIF

The forum accepts JPEGs and PNG, among others, though there's a limit on file size.
Alternatively, you can upload an image to sites such as imgur, and leave a link to it here.

Burngate

LTolledo wrote: ↑
Thu Jan 02, 2020 8:47 pm
... from the schematic ...

https://www.raspberrypi.org/documentati ... educed.pdf

Burngate

I'm no Python expert, and haven't used AdaFruit's matrix bonnet, but one thing stands out: self.parser.add_argument("-t", "--text", help="The text to scroll on the RGB LED panel", default="I love you!") self.parser.add_argument("-t", "--text", help="The text to scroll on the RGB LED panel", default=...

Burngate

Start simple - get one LED to turn on & off. By the time you've achieved that, you'll have learned a huge amount, such things as: - having a resistor in series with it to limit the current - that current goes in circles - you need a ground connection for the current from the GPIO to get back to the ...

Burngate

With that last bit of info, I searched and found http://www.williamosman.com/2017/12/hac ... wands.html
It seems it reflects the IR directly back at the LEDs, not towards any camera.

So have you tried moving the LEDs to behind the camera?

Burngate

So he will have found out that, without a card, there's no Rainbow. Hence the card is at least partly being read. So he can move on, with the added satisfaction of having done something for himself, rather than just asking teacher. Of course, with a Pi 4, he won't have found that out - so back to th...

Burngate

I think the OP is asking (both here and on the other thread) is "Where does the rainbow image come from - the SD card, or before starting to read the card?" One way to find that out is to remove the card. If the rainbow still appears, it must be generated by the Pi. If it doesn't, then the card hold...

Burngate

I would doubt that the Pi is aging, thus needing more current. Rather, your power supplies are the cause. Power supplies are notorious for not doing what they say on the label. And because they have large electrolytic capacitors that can dry out and lose capacitance (possibly because they're in a wa...

Burngate

In order to give a more useful reply, I would need to know where the 8μA - 800μA is coming from and going to, whether it's from a high-impedance source, etc., etc.

Burngate

KleinKravis Joined:Sun Mar 18, 2018 6:14 pm Hardly a beginner ?? Define "beginner" He has 4 posts in two years; fruitoftheloom has 21248 posts in almost six years (10 per day) I've been here longer, but posted less; I know less about Linux than he so am a relative beginner (though I could go on all...

Burngate

A mistake many people make. The data output from the Pi is in the form of a voltage - either 3v3 or 0v - between the GPIO and the Pi's ground. The data the lights expect to receive is the difference in voltage between its data input and its ground. Unless the two grounds are connected together - the...

Burngate

Given that red LEDs have ~2v forward voltage, and green ones have more, and also given that there's a dead zone between sensing high and sensing low, I think the (R1 or R2) 220R isn't doing anything - only the 50k pull-up is in-circuit when the switch is off, with the 1k (R3) pulling down when it's ...

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