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by Z80 Refugee
Wed Jul 04, 2018 10:43 pm
Forum: Automation, sensing and robotics
Topic: super accurate distance measurement with rPi
Replies: 4
Views: 2970

Re: super accurate distance measurement with rPi

You could try putting the tube between the two plates of a capacitor and measure the variation in capacitance caused by the amount of conductive fluid there is between them (ie the water).
by Z80 Refugee
Wed Jul 04, 2018 10:39 pm
Forum: Python
Topic: Switching In a RGB LED?
Replies: 14
Views: 1068

Re: Switching In a RGB LED?

For the scheme I have a CA rgbled with the red green and blue legs getting power from a gpio pin The leg that on a CC rgbled would be ground I have connected to a 3v3 pin So... is that without anything to control the current, like three resistors? The rest is correct, so if it worked before it shou...
by Z80 Refugee
Wed Jul 04, 2018 10:34 pm
Forum: Beginners
Topic: External power for leds
Replies: 5
Views: 790

Re: External power for leds

If I need one extender, can you recommend me one? No, I can't. I know my way around designing electronics - I have not reviewed all the different HATs etc available for the RPi. You need something able to provide 24 outputs (to drive the LEDs) and 24 inputs (to read the buttons), but I expect you w...
by Z80 Refugee
Wed Jul 04, 2018 10:21 pm
Forum: Beginners
Topic: measuring water depth
Replies: 6
Views: 688

Re: measuring water depth

And how does one know what resistors must be used with such devices? The answer is to have a smidge of knowledge about electronics and a schematic diagram of the circuit so you can see what's going on instead of relying on a pictorial representation. Sure, the pictures show you what to do but they ...
by Z80 Refugee
Wed Jul 04, 2018 8:43 am
Forum: Troubleshooting
Topic: MCP23017 input problems
Replies: 4
Views: 249

Re: MCP23017 input problems

I think a proper circuit diagram would be in order, so we can understand what you are trying to do. If you don't have a circuit diagram, how do you know what you are trying to do yourself? -not sure actually... I guess probably you haven't then, so with an open circuit switch (or whatever) there is ...
by Z80 Refugee
Wed Jul 04, 2018 8:38 am
Forum: Python
Topic: Switching In a RGB LED?
Replies: 14
Views: 1068

Re: Switching In a RGB LED?

My code works perfectly for a cathode rgbled, but that broke and without realising it I had bought 100 anode rgbleds. How do I need to code with anode instead of cathode, I know that it is 3v3 instead of gnd. But I havent found help on the internet It's not the code that is the problem (although it...
by Z80 Refugee
Wed Jul 04, 2018 8:27 am
Forum: Beginners
Topic: External power for leds
Replies: 5
Views: 790

Re: External power for leds

I am trying to control 2 high power LEDs(external source) and a button from the Raspberry 3. Beginners Guide to Wiring Things to the GPIO The article above shows you how to connect a basic LED circuit. To run two LEDs from one circuit, you need a resistor per LED, and connect each LED + resistor to...
by Z80 Refugee
Tue Jul 03, 2018 8:39 am
Forum: Beginners
Topic: Sensor Data Over Long wires
Replies: 8
Views: 402

Re: Sensor Data Over Long wires

If you are working with digital data output from a self-contained ultrasonic module, yes (with due consideration to making sure the data actually gets from A to B). If you are trying to operate just the transducers with the actual transmit and receive circuits elsewhere - I would say no (or at least...
by Z80 Refugee
Mon Jul 02, 2018 10:19 pm
Forum: HATs and other add-ons
Topic: Controlling 220 volt with raspberry pi
Replies: 2
Views: 612

Re: Controlling 220 volt with raspberry pi

Hello, I have a raspberry pi 3 and i just started using GPIO pins. So far, i have managed to control Led light. Now i want to control higher voltage. I want to control a 220 voltage with the raspberry pi, but in order to do that there has to be a relay in the circuit. My question is: Is the relay o...
by Z80 Refugee
Mon Jul 02, 2018 10:14 pm
Forum: Beginners
Topic: Sensor Data Over Long wires
Replies: 8
Views: 402

Re: Sensor Data Over Long wires

You would be better off with three RPis (one at each location, running each sensor) which then communicate with each other via Ethernet or Wi-Fi.
by Z80 Refugee
Mon Jul 02, 2018 10:11 pm
Forum: Automation, sensing and robotics
Topic: Massive Switch input and relay output
Replies: 1
Views: 223

Re: Massive Switch input and relay output

Are you willing to build your own, or do you need off-the-shelf?
by Z80 Refugee
Mon Jul 02, 2018 10:08 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: GPIO 17 not working
Replies: 3
Views: 444

Re: GPIO 17 not working

achrn wrote:
Mon Jul 02, 2018 9:00 pm
What am I missing? GPIO17 should work on model B, shouldn't it? It's Stretch, and I've done an apt update and apt upgrade. GPIO17 just seems determined to always report high.
Have you, by any chance, ever shoved 5V onto the pin (even by accident)?
by Z80 Refugee
Mon Jul 02, 2018 10:08 am
Forum: General discussion
Topic: Cooling w/ Razberry daughter board?
Replies: 14
Views: 924

Re: Cooling w/ Razberry daughter board?

Sure, but you can't call it TTL unless it is TTL. With a following wind it could be TTL-compatible, but the ~3V Vhi it could output and still be RPi-safe is marginal for a true TTL input. The bottom line is there is no need to have said "TTL". Loose use of terminology like this misinforms novices, w...
by Z80 Refugee
Mon Jul 02, 2018 8:23 am
Forum: General discussion
Topic: Cooling w/ Razberry daughter board?
Replies: 14
Views: 924

Re: Cooling w/ Razberry daughter board?

From the RaZberry link in post 1: The RaZberry is a tiny daughter card that sits on top of the Raspberry PI GPIO connector not blocking the USB boards. It is powered by the Raspberry PI board with 3.3V and communicates using TTL signals (RX/TX). Who writes this nonsense? Certainly not anyone who und...
by Z80 Refugee
Sun Jul 01, 2018 9:35 pm
Forum: Off topic discussion
Topic: bitcoin mining with external gpu
Replies: 5
Views: 985

Re: bitcoin mining with eternal gpu

So you want to couple PCI interface graphics cards designed for Intel/AMD PC architecture to an SBC comprising an ARM-based system-on-chip which does not expose its data buses even to the card, let alone the rest of the world... good luck with that. I'm not saying it is impossible to simulate a PCI ...
by Z80 Refugee
Sun Jul 01, 2018 6:15 pm
Forum: Beginners
Topic: Top Hat with Breadboard
Replies: 6
Views: 486

Re: Top Hat with Breadboard

Does the OP mean wth the HAT fitted on the breadboard? The problem is that the centre "gutter" on a breadboard is usually 0.3" pitch, whereas the GPIO pins onto which a HAT fits are 0.1" pitch. It is not impossible to make an adapter which breaks out a ribbon to a breadboard (like the T-Cobbler) and...
by Z80 Refugee
Sun Jul 01, 2018 7:31 am
Forum: Automation, sensing and robotics
Topic: Powering the Pi Question
Replies: 5
Views: 565

Re: Powering the Pi Question

I still think this is barking up the wrong tree. Even with completely separate battery management for each cell, the outputs cannot have identical regulation voltages so the unit with the highest voltage will be working to output current and achieve the voltage while the other units are thinking "th...
by Z80 Refugee
Sat Jun 30, 2018 11:22 pm
Forum: General discussion
Topic: Pi Is Too Complicated
Replies: 113
Views: 8683

Re: Pi Is Too Complicated

I agree with that analysis, but the answer is simply for a prospective user to be guided to the most suitable operating environment for their needs. I am very much against the idea of running a full desktop OS "just because you can" when the target of the RPi is introduction to programming and physi...
by Z80 Refugee
Sat Jun 30, 2018 11:07 pm
Forum: Off topic discussion
Topic: Does VPN really help for Internet Privacy?
Replies: 18
Views: 2455

Re: Does VPN really help for Internet Privacy?

However; I think quantum computers are now in use by multiple big entities around the world, and (from them anyway) - privacy is toast. What's your source of information for that assertion? Practical quantum computers are still a pipe dream, regardless of IBM's current public demonstration. If Cont...
by Z80 Refugee
Sat Jun 30, 2018 4:10 pm
Forum: Beginners
Topic: Using fan on Pi
Replies: 22
Views: 5609

Re: Using fan on Pi

Didn't you get what the wink meant?
by Z80 Refugee
Sat Jun 30, 2018 1:16 pm
Forum: Beginners
Topic: 12V Relay Setup
Replies: 12
Views: 1067

Re: 12V Relay Setup

the relay card was recommended to me by https://pollin.de I don't care who recommended it to you - the relay card (as supplied) is not compatible with the RPi so the recommendation is lousy. If you are unwilling to modify it, you need a relay card compatible with the 3.3V logic of an RPi, or to use...
by Z80 Refugee
Sat Jun 30, 2018 11:32 am
Forum: General discussion
Topic: More memory/RAM?
Replies: 36
Views: 16740

Re: More memory/RAM?

Maybe they could make it smaller, but it's not that large anyway, not large enough to cause problems, and doesn't get used continually, so it makes far more sense to focus on getting things right, usable and useful than worrying over size. Any effort of reducing size would effectively be wasted eff...
by Z80 Refugee
Sat Jun 30, 2018 9:13 am
Forum: Automation, sensing and robotics
Topic: Powering the Pi Question
Replies: 5
Views: 565

Re: Powering the Pi Question

Battery power is coming from (4) 18650 LiPo batteries in parallel. It is very bad news to be running batteries in parallel, especially high power / low internal resistance cells like LiPo. Don't do it. If you want a more technical explanation: the individual cells will never be identical, particula...
by Z80 Refugee
Fri Jun 29, 2018 6:24 pm
Forum: General discussion
Topic: More memory/RAM?
Replies: 36
Views: 16740

Re: More memory/RAM?

drgeoff wrote:
Fri Jun 29, 2018 5:45 pm
Given its quite simple functionality, why is it so large?
Because of all the Windows services it has to interface with. A responsive, intuitive operating system makes huge demands on programs written for it (although mostly dealt with by the compiler).

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