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by PiGraham
Wed Dec 06, 2017 1:35 pm
Forum: Beginners
Topic: Continuous rotation servo control.
Replies: 6
Views: 198

Re: Continuous rotation servo control.

pcmanbob wrote:
Wed Dec 06, 2017 12:52 pm
So the reason your servo does not stop is because you have not told it to.
Agreed.

It may be the case that no PWM signal will stop the servo.
If not it may be necessary to maintain the mid-position signal and not quit with GPIO.Cleanup().
by PiGraham
Wed Dec 06, 2017 8:41 am
Forum: Media centres
Topic: Skype + Raspberry pi
Replies: 9
Views: 2022

Re: Skype + Raspberry pi

No recommendations, I only know what I read in these pages,, but this looks interesting as a Skype alternative:

http://www.instructables.com/id/Video-C ... erry-Pi-3/

https://www.linux-projects.org/uv4l/tut ... itsi-meet/

It seems not to need binaries and is open source.
by PiGraham
Wed Nov 29, 2017 10:56 am
Forum: General discussion
Topic: Scanning serial UART ports
Replies: 3
Views: 116

Re: Scanning serial UART ports

You can read the Rx pin as a general input. If it's state when driven by the device's Tx output is different to the state when open circuit you should be able to detect that the device is plugged in. You can probably just read it like any gpio. You can't tell what is connected unless the something t...
by PiGraham
Sat Nov 11, 2017 9:33 am
Forum: Beginners
Topic: Detect hot shoe trigger from analogue camera
Replies: 10
Views: 407

Re: Detect hot shoe trigger from analogue camera

just a thought about another way to tackle this. You could use a car GPS GSM tracker. these can send an SMS of position, date, time when a button is pressed. You could wire the flash sync to the button contacts. It could also be used to locate the camera if you lose it. Battery and gps stuff already...
by PiGraham
Thu Nov 09, 2017 3:15 pm
Forum: Beginners
Topic: Detect hot shoe trigger from analogue camera
Replies: 10
Views: 407

Re: Detect hot shoe trigger from analogue camera

You can get hotshow adaptors designed to connect off-cara flash units. They generally take a hotshoe flash in top as well to you can tap off the flash contact to the Pi and still have a way to use a flash is desired. Be careful though, some flash guns can have high voltages on the shoe contacts. Us ...
by PiGraham
Tue Nov 07, 2017 2:36 pm
Forum: General discussion
Topic: Extending Wireless Range
Replies: 55
Views: 2044

Re: Extending Wireless Range

You all worry too much. The point is not to do whatever illegal acts you can get away with. These laws exist for good purposes and it makes sense to comply with them to avoid interfering with other peoples' Wi-Fi and other equipment. Everyone benefits if we are not blasted with signals from every W...
by PiGraham
Tue Nov 07, 2017 11:22 am
Forum: Gaming
Topic: ZXBaremulator v2.0
Replies: 3
Views: 386

Re: ZXBaremulator v2.0

by PiGraham
Tue Nov 07, 2017 8:18 am
Forum: General discussion
Topic: Extending Wireless Range
Replies: 55
Views: 2044

Re: Extending Wireless Range

]Once again, the authorities are not going to come after you if you are using the Hats or Breadboards to hack something together to make a better mousetrap. That is why I and thousands of others who grew up during the Home Brew Computer days, are not running around with tinfoil on our heads. At thi...
by PiGraham
Tue Nov 07, 2017 6:44 am
Forum: Beginners
Topic: Which hardware to buy: Simple sign project, Stranger Things
Replies: 5
Views: 240

Re: Which hardware to buy: Simple sign project, Stranger Things

I agree "neopixels" are the obvious choice. Something like this https://i.ebayimg.com/images/g/XMQAAOSwMORW7SXw/s-l500.jpg https://www.ebay.co.uk/itm/DC-5V-50PCS-WS2811-RGB-Full-Color-12mm-Pixels-digital-Addressable-LED-String-CC/162705886727?_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D2%26asc%3D...
by PiGraham
Mon Nov 06, 2017 7:09 am
Forum: Automation, sensing and robotics
Topic: L293D troubleshooting for IR camera cut control
Replies: 27
Views: 5951

Re: L293D troubleshooting for IR camera cut control

Hi, Great information. Cheers :) One question, where would be the best place put a LDR sensor in your circuit? Thanks. Diogo Why do you need an LDR when you have an image sensor? Take a picture and measure brightness from that. If the average is below some threshold then it's too dark and you shoul...
by PiGraham
Mon Oct 30, 2017 11:52 am
Forum: Advanced users
Topic: How to transmit binary values with serial port
Replies: 23
Views: 2665

Re: How to transmit binary values with serial port

I am new to serial port communication and facing similar problem of receiving junk values while using putty.. Hi, mrmuffins hope you have resolved the issues ,if yes request you to guide me . I am trying to send some string data from raspberry pi3 but getting similar display while using putty as yo...
by PiGraham
Sun Oct 29, 2017 7:02 pm
Forum: Automation, sensing and robotics
Topic: Proximity or Line Crossing Sensor System
Replies: 3
Views: 191

Re: Proximity or Line Crossing Sensor System

Maybe you could use RFID tags and readers. Are the horses already tagged? Sure Flap cat doors have an RFID detector coil around the outer aperture that reads the implanted tag on in the neck when the cat puts its head up to the flap. Perhaps a much larger coil could be places around each of several ...
by PiGraham
Fri Oct 27, 2017 1:07 pm
Forum: Networking and servers
Topic: How to get a Raspberry Pi to communicate over 10km (6 miles)
Replies: 13
Views: 982

Re: How to get a Raspberry Pi to communicate over 10km (6 miles)

This video hows 10km range with ESP32 and high gain antenna. A Pi could possibly do something similar. IIRC the Pi3 has pads on board that can be used for external antenna connection. https://hackaday.io/project/10091-raspberry-pi-3-external-antenna You could also look at LoRa. https://www.youtube.c...
by PiGraham
Fri Oct 27, 2017 9:42 am
Forum: Beginners
Topic: Controlling Solenoid Valve
Replies: 7
Views: 408

Re: Controlling Solenoid Valve

If you are prepared to motorise a manual valve there are a few options. Mixer valves are designed to mix flows. Cheap thermostatic radiator valves operate by pressing on a valve with an expanding wax-filled cylinder in the control knob. If you remove the knob the actuating button of the valve is exp...
by PiGraham
Mon Oct 23, 2017 8:55 am
Forum: Beginners
Topic: Controlling Solenoid Valve
Replies: 7
Views: 408

Re: Controlling Solenoid Valve

Do solenoid Valves only have two settings i.e Full Open or Full Closed...there is no way to get them to only open 30% (this is only an example) ? If this is the case that they can only open and close, what would you recommend I use to open a valve certain increments? Typically yes, solenoid valves ...
by PiGraham
Tue Oct 17, 2017 6:31 am
Forum: General discussion
Topic: Remote email printing
Replies: 5
Views: 282

Re: Remote email printing

They have a POS system, touch screen front counter, touch screen in prep area for call in with POS receipt printer in prep area (doesn't have a problem with flour). I think you're thinking another touch display over the prep area. Would require me to start an entirely new business. The current POS ...
by PiGraham
Mon Oct 16, 2017 2:45 pm
Forum: General discussion
Topic: Remote email printing
Replies: 5
Views: 282

Re: Remote email printing

Paper seems like a bad idea. Can't you go paperless? Can't you display orders on a screen that can indicate which are open, which fulfilled, prep time, collected etc? Some non-touch gesture sensors could allow hygienic review and updating. If the ordering site collected mobile numbers you could even...
by PiGraham
Mon Oct 16, 2017 9:09 am
Forum: Python
Topic: pi3d - merge shapes of two different colors
Replies: 3
Views: 317

Re: pi3d - merge shapes of two different colors

I don't much about Pi3D but maybe you can apply a texture to the merged shape to colour it. Alternatively keep the parts as separate meshes with their own colours. There is an AddChild function. Would that allow you to add the ball as a child of a stick so that you can move both as a unit? The Tiger...
by PiGraham
Fri Oct 13, 2017 8:16 am
Forum: General discussion
Topic: Why do new forum members not come back?
Replies: 42
Views: 3130

Re: Why do new forum members not come back?

Maybe they read the answers but there is no feedback from OP. Last Active time in profile may show this but s/he can read the answer without login. It would certainly be disappointing if replies were never even read but I think the "no feedback from OP" is the issue. Why is there no feedback from t...
by PiGraham
Thu Oct 12, 2017 9:27 pm
Forum: Python
Topic: Comparing two images using PIL
Replies: 13
Views: 738

Re: Comparing two images using PIL

I'm trying to compare two images and get a number value. What comparison do you want to make? Comparing histograms can be a good technique for similar images. It is relatively unaffected by scale or rotation and quick to compute, but it ignores details and what the image actually contains as object...
by PiGraham
Thu Oct 12, 2017 3:34 pm
Forum: Troubleshooting
Topic: Stuttering Servos / Intermittent Servo
Replies: 5
Views: 201

Re: Stuttering Servos / Intermittent Servo

powered with a 9V battery Is your servo rated for 9V? If it's designed for 4.8V it may have died from over voltage. It seems specs vary a lot. It may be rated to 10V and be fine, or not. Do you have any way to test that it still works? Going to higher voltages can destroy servos, so testing the upp...
by PiGraham
Mon Oct 09, 2017 9:25 am
Forum: Beginners
Topic: Conecting dual sd cards
Replies: 5
Views: 277

Re: Conecting dual sd cards

USB reader is the easy option but you can connect SD card on SPI bus.
https://ralimtek.com/Raspberry_Pi_Secondary_SD_Card/
by PiGraham
Mon Oct 02, 2017 6:48 pm
Forum: Automation, sensing and robotics
Topic: connecting multiple magnetic switches
Replies: 10
Views: 709

Re: connecting multiple magnetic switches

How far apart are these doors and windows? Running long wires to 3.3v logic inputs could lead to false alarms due to electrical interference.
by PiGraham
Mon Oct 02, 2017 4:32 pm
Forum: General discussion
Topic: Cycling Sensors for Cycling Computer
Replies: 12
Views: 788

Re: Cycling Sensors for Cycling Computer

What Model would be best for a cycling computer, because from what ive looked at the Raspberry Pi Model 3 satisfies what I need for the cycling computer? Model 3 is OK. Pi Zero uses less power which gives longer life on batteries. Any model Pi will have limited life on battery compared to a typical...
by PiGraham
Sun Oct 01, 2017 3:51 pm
Forum: Beginners
Topic: 3W 850nm leds working voltage?
Replies: 29
Views: 1380

Re: 3W 850nm leds working voltage?

I have a different opinion. I think all four of the nuts and bolts that connect the two LED board to the camera board are ground. Each board has one other external connection - the terminal with the cross-head screw. Those two terminals should be wired together and to a positive supply voltage. Wha...

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