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by tenochtitlanuk
Fri Jan 26, 2018 7:51 pm
Forum: Troubleshooting
Topic: GPIO not producing power but gpio readall says it should
Replies: 2
Views: 101

Re: GPIO not producing power but gpio readall says it should

Are you connecting the cooler ( ?fan?) directly to the GPIO pin and expecting it to deliver enough powere? Or are you using the necessary bipolar/mosfet/IC driver? Have you tried a LED and resistor of say 470 ohms from the GPIO to earth, being careful to get polarity right??
by tenochtitlanuk
Sun Dec 31, 2017 11:00 pm
Forum: Troubleshooting
Topic: 12V Motor controlled via Transistor Switch issue
Replies: 12
Views: 437

Re: 12V Motor controlled via Transistor Switch issue

I'd bet heavily that you are using the diode the wrong way round. When the transistor is turned on it ( the diode) will pass most of the current and the motor will hardly get any. Meanwhile the excessive current is frying your transistors. The diode should be oriented so it seems it would never cond...
by tenochtitlanuk
Wed Dec 20, 2017 10:25 am
Forum: Raspberry Pi Desktop for PC and Mac
Topic: Installing Raspberry Pi Desktop on ACER Netbook
Replies: 4
Views: 460

Re: Installing Raspberry Pi Desktop on ACER Netbook

I can run the USB stick version happily on my Acer Aspire One, but installing fails- it gets part way through but doesn't find the keyboard and mouse, and offers only to install to the USB key, not showing the HDD as an option! Only pertinent error seems to be it can't find files called 'b43/ucode15...
by tenochtitlanuk
Thu Aug 10, 2017 4:28 pm
Forum: General discussion
Topic: Running x86 apps on ARM
Replies: 81
Views: 80017

Re: Running x86 apps on ARM

When you are into your seventies it is nice to be able to run familiar software. I enjoy Python et al, but started out on versions of BASIC decades ago. I tried the 3-day free-trial of Exagear and found it did indeed let me run the x86 'Liberty BASIC' which is a favourite, on my Pi's.. Paying for it...
by tenochtitlanuk
Thu Jun 22, 2017 8:18 pm
Forum: Beginners
Topic: linear atuator control using raspberry
Replies: 2
Views: 499

Re: linear atuator control using raspberry

You don't say how much electronics knowledge you have, nor level of Python skills. Spec. says motors are standard 12V 5A brushed motors. To run two you'll need a hefty power supply, separate from the Pi. Switching this voltage from a Pi's 0/3.3V output would need a logic-level power mosfet. But to r...
by tenochtitlanuk
Sat May 06, 2017 8:38 pm
Forum: General discussion
Topic: I have problems with my electronic circuit
Replies: 34
Views: 2555

Re: I have problems with my electronic circuit

Your photo looks like you think the rows of five contacts on each side of your board are connected. They are not. Your photo shows the 1k and 10k resistors in series, with the connected junction seeming to go nowhere. If you connect d and s the wrong way round, the mosfet will indeed conduct irrespe...
by tenochtitlanuk
Wed Mar 15, 2017 10:19 am
Forum: Automation, sensing and robotics
Topic: Simple Relay Circuit
Replies: 10
Views: 1431

Re: Simple Relay Circuit

SSRs stay in a low resistance on state until the load current/voltage drops to a low, near-zero value. That is why they are used on AC power. Your circuit shows DC power to the SSR/relay. If the relay coil draws an appreciable current it will stay latched on until the power is removed! Are you relyi...
by tenochtitlanuk
Fri Feb 17, 2017 12:06 am
Forum: Mathematica
Topic: An equation to generate the output of a driven RC circuit.
Replies: 11
Views: 3723

Re: An equation to generate the output of a driven RC circui

I know you intend to use Mathematica, but it is indeed very easy to code/simulate in your language/GUI of choice. I used initial conditions t =0 dt =1E-6 ' time step 1 microsecond C =10E-6 ' 10 microfarads R =1E3 ' 1 kilo ohm ( so time constant is 10 ms) f =1E2 ' 100 Hz amp =5 ' 5 volts and ( pseudo...
by tenochtitlanuk
Wed Feb 08, 2017 12:00 pm
Forum: Beginners
Topic: Measuring strain on a bike frame
Replies: 5
Views: 830

Re: Measuring strain on a bike frame

Sounds a fun and very do-able project. Note that strain gauges measure strain, ie ( we hope elastic-) deformation. It will be hard to deduce the actual stress producing the deformation, so you can't really see if you are reaching stresses near the elastic limit. If you see PERMANENT strain then you ...
by tenochtitlanuk
Mon Jan 23, 2017 8:23 pm
Forum: C/C++
Topic: I just 'open sourced' my SSD1306 I2C OLED code
Replies: 11
Views: 2440

Re: I just 'open sourced' my SSD1306 I2C OLED code

Mea culpa. I eventually tried what should have been obvious and tried another lead. Had been misled by the green power LED into thinking it was connected. Mint & Python now see it with no trouble! Thanks for taking the trouble to comment...
by tenochtitlanuk
Sun Jan 22, 2017 8:48 pm
Forum: C/C++
Topic: I just 'open sourced' my SSD1306 I2C OLED code
Replies: 11
Views: 2440

Re: I just 'open sourced' my SSD1306 I2C OLED code

Perhaps off-topic on a Pi forum, but relevant.... I've been trying to use the Adafruit ft232h breakout from a fully up-to-date Linux Mint installation on a desktop. It steadfastly refuses to be seen as a usb or tty device. The installation followed Adafruit's instructions, and the Adafruit_FTDI and ...
by tenochtitlanuk
Tue Oct 04, 2016 6:45 pm
Forum: General discussion
Topic: Sysiphus Art Table
Replies: 1
Views: 290

Re: Sysiphus Art Table

Bruce Shapiro and Brian Schmalz certainly inspired me. It was one of my first applications of my first Pi to apply it to an EggBot, as posted on this forum way-back. Bruce's work is genuinely artistic rather than mechanistic- a quantum leap on from turtle-graphics ( which I've had a lot of fun with)...
by tenochtitlanuk
Sun Sep 25, 2016 8:16 am
Forum: Automation, sensing and robotics
Topic: can i use ultrasonic sensor to capture an image?
Replies: 6
Views: 984

Re: can i use ultrasonic sensor to capture an image?

Again no. I'm talking about raw sensors, not ultrasound range-meters. May seem dark ages to you, but easily available now and for decades. But certainly not a beginner project. Several Pi ( and other) projects have indeed scanned horizontally with range-meters and drawn a 'map', but this is not an i...
by tenochtitlanuk
Sat Sep 24, 2016 4:00 pm
Forum: Automation, sensing and robotics
Topic: can i use ultrasonic sensor to capture an image?
Replies: 6
Views: 984

Re: CAN I USE ULTRASONIC SENSOR TO CAPTURE AN IMAGE?

Yes. ( sorry, mikronauts! Couldn't resist the lure of your terse reply!) But only slowly.... and in a sense.... and not quickly! Sairo- don't read on if your programming and physics is not yet moderately advanced! Mikronaut has given a link to an example of ultrasound detection as such... :D Most ul...
by tenochtitlanuk
Tue Sep 20, 2016 9:17 pm
Forum: Mathematica
Topic: Is Wolfram still developing for Raspberry Pi?
Replies: 5
Views: 6137

Re: Is Wolfram still developing for Raspberry Pi?

I too have wondered. Safely retired from teaching for a decade, my first thought when I heard it was available on the Pi was 'what a fantastic resource. I'd have died to have access to that as a student.'. Apart from one magazine article I've seen nothing to suggest it has gained any foothold via Pi...
by tenochtitlanuk
Sun Aug 21, 2016 6:43 pm
Forum: Troubleshooting
Topic: Driving a SSR with a ULN2003a
Replies: 3
Views: 1100

Re: Driving a SSR with a ULN2003a

Hard to read your drawn circuit. Here's what I'd use. You may need "Show Image' to see at decent size... http://www.diga.me.uk/PiDrivingSSRb.gif NB Wire the high voltage side safely!! 1 Wire the SSR and load and fuse. Check that a 4.5V battery on the input terminals switches the load on. CARE- mains...
by tenochtitlanuk
Thu Aug 18, 2016 7:10 am
Forum: Troubleshooting
Topic: Can't SSH into my RPI3 anymore
Replies: 3
Views: 3711

Re: Can't SSH into my RPI3 anymore

I've been ssh-ing into my various Pi's for three years with no problems, but recently had a very similar problem. It seems I'd confused the router by swapping rapidly between several pi's and different cards successively sometimes in one and sometimes the other, and even tho' I used correct address ...
by tenochtitlanuk
Sat Aug 13, 2016 4:29 pm
Forum: Beginners
Topic: How do you boot an image
Replies: 2
Views: 444

Re: How do you boot an image

Suggest you look at https://www.raspberrypi.org/learning/so ... uickstart/ and skip down the page to where it tells you how to copy an img file ( they are referring to the Raspbian image) onto an SD cart. Then just insert it in your Pi and away you go...
by tenochtitlanuk
Mon Jun 13, 2016 8:02 pm
Forum: Camera board
Topic: Camera trap
Replies: 21
Views: 3167

Re: Camera trap

Thanks Gregeric for your contribution- it's what I was trying to do back in 2013 in the early days of pi...
by tenochtitlanuk
Mon Jun 13, 2016 6:14 pm
Forum: Automation, sensing and robotics
Topic: Waterproof ultrasonic sensor
Replies: 5
Views: 1662

Re: Waterproof ultrasonic sensor

If you are planning to use UNDERWATER, be aware that descriptions of transducers you're presently looking at as 'waterproof' simply mean they should be OK in a splashy environment. They are NOT for underwater use. Sound travels much faster in water. Transducer shape and power & frequency for underwa...
by tenochtitlanuk
Sat Apr 30, 2016 9:38 am
Forum: Automation, sensing and robotics
Topic: regarding light sensor can't detect ANYTHING
Replies: 3
Views: 583

Re: regarding light sensor can't detect ANYTHING

Python goes round 0-->10 very fast. Better to use a delay or longer loop, or terminate on a key-press??
by tenochtitlanuk
Mon Mar 07, 2016 10:04 am
Forum: Add-ons
Topic: How does a 4 pin Infrared Object Sensor work ?
Replies: 4
Views: 1243

Re: How does a 4 pin Infrared Object Sensor work ?

I think you are confusing two different TYPES of circuit. What you have is a 'retro-reflective' device, which transmits a near-IR signal and detects its reflection from a nearby object. The 3-pin ones with a white dome are passive detectors of heat radiation further into the IR from warm objects nea...
by tenochtitlanuk
Sun Feb 28, 2016 9:47 pm
Forum: Other languages
Topic: FUZE BASIC is now on Rosetta Code
Replies: 55
Views: 5714

Re: FUZE BASIC is now on Rosetta Code

I belong to the minimalist school too- comes of doing my first coding on a 256 byte machine! re Rosetta Code- I'd recommend it to any budding coder. I've added quite a few solutions in another language... it gives you a challenge, and supplies so many other language solutions to adapt that as a by-p...
by tenochtitlanuk
Mon Dec 28, 2015 12:29 am
Forum: Troubleshooting
Topic: RPi V2 Will Not Reboot - need help!
Replies: 10
Views: 1046

Re: RPi V2 Will Not Reboot - need help!

Just a thought- your OP ( original post) says you used sudo dd if=/dev/disk4 of=~/SDCARDBU.dmg I'd have expected the command to have 'bs=4M' within it, and images are usually named ending in '.img' and not ',dmg'. A moment later you are using- sudo dd if=~/SDCARDBU of=/dev/disk4 which I'd expect to ...

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