Go to advanced search

by PiGraham
Mon Jun 18, 2018 8:27 am
Forum: Troubleshooting
Topic: Wrong screen resolution of Raspbian in VNC Viewer
Replies: 2
Views: 72

Re: Wrong screen resolution of Raspbian in VNC Viewer

I think Real VNC default is to show the native desktop resolution and that changes if you don't have HDMI display attached because the Pi uses analog ideo out if no HDMI. If that is your issue you can fix the display to always use HDMI (force_hotplug=1 in config.txt IIRC) You can force a resolution ...
by PiGraham
Fri Jun 15, 2018 6:15 pm
Forum: Python
Topic: Pi controlled RC car
Replies: 5
Views: 297

Re: Pi controlled RC car

I suggest you do not connect the Pi 5V to the battery positive / motor terminals. Power the Pi from a separate power source such as USB power bank. That protects the Pi from fluctuations of low and high voltage due to battery discharge, motor load high voltages due to "back emf" that can occur when ...
by PiGraham
Fri Jun 15, 2018 6:05 pm
Forum: Python
Topic: Pi controlled RC car
Replies: 5
Views: 297

Re: Pi controlled RC car

Hi, thank you for the answer. About the wiring: since I'm a newbie to the breadboard wiring (and also a newbie to RasPi in general), can I ask you to explain in a very basic way what "ground rail of the breadboard" means? About the photos: I just thought the were useless since they would be identic...
by PiGraham
Fri Jun 15, 2018 1:44 pm
Forum: Beginners
Topic: How to stop multiple detection of button press?
Replies: 8
Views: 201

Re: How to stop multiple detection of button press?

Your code is only testing the current state. If you want one action when the button is presed to need to detect when the input changes state . input = GPIO.input(23) if input == True: print "email sent" The above will kep printing "email sent" over and over as long as the button is pressed. You can ...
by PiGraham
Fri Jun 15, 2018 11:04 am
Forum: Beginners
Topic: How to stop multiple detection of button press?
Replies: 8
Views: 201

Re: How to stop multiple detection?

If you record the time when a keypress occurs you can check how long it has been when the next keypress occurs. If it's too soon just ignore itelse just update the time
by PiGraham
Mon Jun 11, 2018 7:53 pm
Forum: Automation, sensing and robotics
Topic: Raspberry Pi communication over radio
Replies: 5
Views: 378

Re: Raspberry Pi communication over radio

A radio antenna above ground works much better than one on the ground. If you put GPS on the rocket and transmit position during descent that may help finding the rocket on the ground more than the radio after touchdown. You could also try using a directional antenna (e.g. Yagi, parabolic) to get a ...
by PiGraham
Mon Jun 11, 2018 2:57 pm
Forum: Other projects
Topic: Is possible with Raspberry 3 emulate USB or PS/2 keyboard?
Replies: 2
Views: 198

Re: Is possible with Raspberry 3 emulate USB or PS/2 keyboard?

You can probably do PS/2 on gpio but USB would need gadget mode which is only available on PiZero (maybe Pi A/A+)
by PiGraham
Mon Jun 11, 2018 2:55 pm
Forum: Automation, sensing and robotics
Topic: Raspberry Pi communication over radio
Replies: 5
Views: 378

Re: Raspberry Pi communication over radio

You could use something basic like a 433MHz keyfob remote https://uk.rs-online.com/web/p/products/8430812/?grossPrice=Y&cm_mmc=UK-PLA-DS3A-_-google-_-PLA_UK_EN_Semiconductors-_-Semiconductor_Development_Kits%7CRadio_Frequency_Development_Kits-_-PRODUCT+GROUP&matchtype=&gclid=Cj0KCQjwu_jYBRD8ARIsAC3E...
by PiGraham
Mon Jun 11, 2018 2:37 pm
Forum: Camera board
Topic: Night-vision camera taking day-vision pictures
Replies: 4
Views: 253

Re: Night-vision camera taking day-vision pictures

This probably isn't the best place to ask about third-party add-ons.

How are you powering the IR LEDS?

How is the integrated IR cut filter controlled? If that switches in you will block the light from the LEDs
by PiGraham
Mon Jun 11, 2018 10:13 am
Forum: Networking and servers
Topic: Remote Access to PI behind any network
Replies: 12
Views: 495

Re: Remote Access to PI behind any network

The main problem is this: Even though the PI will be connected to WIFI at this facility, the network port of the PI will have a device connected to it which I need to program remotely. The programming software can't run on the PI. So, essentially, the PI will be used as a WIFI Bridge for this parti...
by PiGraham
Sun Jun 10, 2018 9:08 pm
Forum: Networking and servers
Topic: Remote Access to PI behind any network
Replies: 12
Views: 495

Re: Remote Access to PI behind any network

I think you can run Team Viewer on Pi and that works well to allow access into a network without configuration. AFAIK bothe ends must have internet access to TeamViewer's servers to make contact though.

See also "reverse VNC" and "reverse SSH tunnel"
by PiGraham
Wed Jun 06, 2018 3:47 pm
Forum: Python
Topic: Read multiple numbers from 4x4 keypad
Replies: 11
Views: 248

Re: Read multiple numbers from 4x4 keypad

Thanks scotty101
by PiGraham
Wed Jun 06, 2018 3:09 pm
Forum: Python
Topic: Read multiple numbers from 4x4 keypad
Replies: 11
Views: 248

Re: Read multiple numbers from 4x4 keypad

If you want to read a number of digits just add to a string on each keypress event. If you are using the eample ode it just prints the current key. def printKey(key): print(key) # printKey will be called each time a keypad button is pressed keypad.registerKeyPressHandler(printKey) If you define a gl...
by PiGraham
Tue Jun 05, 2018 5:59 pm
Forum: General discussion
Topic: Tranquility Project
Replies: 59
Views: 1456

Re: Tranquility Project

bensimmo wrote:
Tue Jun 05, 2018 4:14 pm
We got 1km up with our rocket, does that count? (and a school).
I'd count that as a great success, so long as you weren't expecting to reach the moon.
Well done!
by PiGraham
Tue Jun 05, 2018 2:25 pm
Forum: Beginners
Topic: SMS without internet
Replies: 2
Views: 80

Re: SMS without internet

If you are lucky you might find you are in a location covered by LoRaWAN https://lora-alliance.org/ In which case you could use a LoRa radio module to talk to a local gateway to connect to SMS or Internet. Shop around for celular deals. Pare down your data to send a few SMS as possible. Can you only...
by PiGraham
Tue Jun 05, 2018 12:47 pm
Forum: General discussion
Topic: Tranquility Project
Replies: 59
Views: 1456

Re: Tranquility Project

jamesh wrote:
Tue Jun 05, 2018 12:29 pm
And no school has a titanium printer!
Indeed. And nobody else has a rocket fuel printer.

It's great to pusue a dream, but it takes focus on the how to make it a reality. Otherwise it's pie in the sky rather than Pi on the moon.
by PiGraham
Tue Jun 05, 2018 12:42 pm
Forum: General discussion
Topic: Tranquility Project
Replies: 59
Views: 1456

Re: Tranquility Project

Wow this is new? https://www.wired.com/story/darpas-little-launch-challenge/?mbid=social_fb_onsiteshare https://www.darpalaunchchallenge.org/ Wonder if Dave Ackerman is up for the challenge? Launch a rocket from one of his balloons? I'll get excited about that once someone gets anywhere close to an...
by PiGraham
Tue Jun 05, 2018 12:28 pm
Forum: General discussion
Topic: Tranquility Project
Replies: 59
Views: 1456

Re: Tranquility Project

Most of this stuff has been figured out, including getting stuff down to the Moon's surface. http://www.tethers.com/EDTethers.html Thanks to the Internet all those old papers are now available, I can now read them to make sure I'm not talking s... ;) But now it no longer needs any Country's space a...
by PiGraham
Tue Jun 05, 2018 11:28 am
Forum: General discussion
Topic: Tranquility Project
Replies: 59
Views: 1456

Re: Tranquility Project

Gavinmc42 wrote:
Tue Jun 05, 2018 11:08 am

The bolo is slower so junk comes to it ;)
But you have to catch hold of it and equalise velocity or else it will fly right by. You need a big net, a way to bind the junk into a reasonably rigid structure and propulsion to maintain orbit in the right place to collect junk.
by PiGraham
Tue Jun 05, 2018 11:23 am
Forum: General discussion
Topic: Tranquility Project
Replies: 59
Views: 1456

Re: Tranquility Project

You are touching on space elevators, but while they can allow slow efficient clean ascent to orbit they can't get you to escape velocity, I think. What makes the rotating bolo interesting is the energy storage to provide a boost to do that. It does need just as much energy input, but it can be done ...
by PiGraham
Tue Jun 05, 2018 10:48 am
Forum: General discussion
Topic: Tranquility Project
Replies: 59
Views: 1456

Re: Tranquility Project

I think we are confusing the rotation required to keep the mass pointing in the same direction (tether towards earth) and the orbital velocity required to hold it at a certain orbit height (spinning a tennis ball on string around your head). You would need to add more and more energy to raise the m...
by PiGraham
Tue Jun 05, 2018 10:01 am
Forum: General discussion
Topic: Tranquility Project
Replies: 59
Views: 1456

Re: Tranquility Project

Yep. The amount of energy required to rotate the mass once in orbit is negligible compared to the energy required to get it to an orbital velocity the first place. An astronaut could rotate a whole satellite using their arm strength alone. Collecting the "junk" and bringing it all in the the same o...
by PiGraham
Tue Jun 05, 2018 9:10 am
Forum: General discussion
Topic: Tranquility Project
Replies: 59
Views: 1456

Re: Tranquility Project

If you could gather mass from space junk wouldn't you still need lots of energy to spin it up? The junk is already moving around the earth at orbital velocity, it isn't just sitting their at zero speed or it would just fall back down to earth. What do you mean by "spin it up"? I think many of you w...
by PiGraham
Tue Jun 05, 2018 8:53 am
Forum: General discussion
Topic: Is camera module lens inside the rim waterproof?
Replies: 8
Views: 283

Re: Is camera module lens inside the rim waterproof?

So, I gather that there could be some fogging up of the small glass window (or optical flat) even if the enclosure were to be totally sealed / water-proofed? But since this particular installation will be under an overhanging roof and completly protected from rain, maybe another option might be, as...
by PiGraham
Tue Jun 05, 2018 8:44 am
Forum: General discussion
Topic: Tranquility Project
Replies: 59
Views: 1456

Re: Tranquility Project

Probably used the wrong term, momentum and not gravity. https://en.wikipedia.org/wiki/Momentum_exchange_tether. Collect all the LEO space junk as the mass for the spinning skyhook. Other names - Bolo/Rotovator, not the same as a space elevator. 1kg Rover needs x Delta V? Railgun? Translunar Taxi? H...

Go to advanced search