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by NGC6543
Thu Apr 25, 2019 2:34 pm
Forum: Beginners
Topic: How to calculate resistors...
Replies: 68
Views: 2651

Re: How to calculate resistors...

...but would this (100mA) damage something else in the RPi or would that case be what I asked earlier - where the RPi would just not have enough power to do this... Think of it this way: All the available current has to be supplied through something, for all the GPIO pins. I've no idea what the exa...
by NGC6543
Tue Apr 23, 2019 12:07 pm
Forum: Automation, sensing and robotics
Topic: RF receiver for 926.365 MHz
Replies: 11
Views: 828

Re: RF receiver for 926.365 MHz

A $10/£10 SDR dongle and GNUradio on the Pi is probably quite suited to that task. You might need to decode the data the units send when activated, or record it for comparison. GNUradio can help with that. GNUradio looks really complicated at first, but it's actually not hard to use when you go thro...
by NGC6543
Mon Apr 22, 2019 12:59 pm
Forum: Automation, sensing and robotics
Topic: RF receiver for 926.365 MHz
Replies: 11
Views: 828

Re: RF receiver for 926.365 MHz

What are you trying to receive? That's quite a specific frequency. As said above me, and RTL-SDR dongle is an easy way to receive it. Although GNUradio supposedly runs on the Pi, I would run it on a PC and use a Pi as the remote connection to the RTL up near the antenna. Funnily enough, that's what ...
by NGC6543
Wed Apr 17, 2019 10:21 am
Forum: C/C++
Topic: Making sense of ADS-B checksums & bitfields
Replies: 52
Views: 5897

Re: Making sense of ADS-B checksums & bitfields

It's 69mm*, not 89, just in case that's not a typo, but otherwise yes, that's how I made it. I cut the four radials so that one end was left with a sharp point so I could ram them into the cable, between the outer casing and the screen to contact the screen. You could use any method to attach to the...
by NGC6543
Mon Apr 15, 2019 9:32 pm
Forum: C/C++
Topic: Making sense of ADS-B checksums & bitfields
Replies: 52
Views: 5897

Re: Making sense of ADS-B checksums & bitfields

How do you connect your handcrafted antennas to the receiver SMA input? The wire collinear (pictures a few posts above) was shoved into the centre of the TV socket end of the pigtail that came with my dongle. The outer (metal) of the TV socket was wedged into a hole in another coffee can. The curre...
by NGC6543
Mon Apr 15, 2019 5:04 pm
Forum: C/C++
Topic: Making sense of ADS-B checksums & bitfields
Replies: 52
Views: 5897

Re: Making sense of ADS-B checksums & bitfields

OK, I join your coffee can DIYS antenna club, would this be a start to get the software setup: If you are mostly/only interested in using the SDR for ADS-B, FlightAware produce one: https://flightaware.com/adsb/prostick/ I have the plus version inbound from ModMyPi. I think the Plus version is only...
by NGC6543
Sun Apr 14, 2019 2:44 pm
Forum: General discussion
Topic: Retired old android smartphone's (HELP PLEASE)
Replies: 11
Views: 902

Re: Retired old android smartphone's (HELP PLEASE)

Most modern electronics things aren't worth the effort of scavenging parts from, and I'm a die-hard component recycler. I used to keep a load of old server and PC boards for parts but only ever took the occasional capacitor, inductor, connector or pried off a chip heatsink. And those multilayer boar...
by NGC6543
Sat Apr 13, 2019 8:59 pm
Forum: General discussion
Topic: Have a laugh at my quality antenna
Replies: 7
Views: 709

Re: Have a laugh at my quality antenna

You need a RTL2832U TV reciever/SDR USB dongle. They are really cheap for a basic one (around £10, $10) and the whole installation is quite easy really. First you install the RTL2832U driver on the Pi. After that, you can use the SDR function itself, by installing free SDR software on either the Pi ...
by NGC6543
Sat Apr 13, 2019 4:25 pm
Forum: C/C++
Topic: Making sense of ADS-B checksums & bitfields
Replies: 52
Views: 5897

Re: Making sense of ADS-B checksums & bitfields

I thought I would give that Sprut's collinear a try. I'll do my Franklin when I get a bit more time - want to do that more accurately. This is some stripped 2.5sq.mm mains cable, with loops, and stuffed into the top of the TV tail socket that came with my dongle. I'll see how it does over the next f...
by NGC6543
Sat Apr 13, 2019 12:04 pm
Forum: Raspbian
Topic: getting gps to work on raspberry pi 3
Replies: 23
Views: 2110

Re: getting gps to work on raspberry pi 3

Is it an active antenna, and have you put it at a window, or better yet, outside? Even an active antenna might struggle indoors, but if you put it out for a while it should be able to maintain a fix when you take it back indoors. First, it needs to get the complete GPS almanac from the transmissions...
by NGC6543
Sat Apr 13, 2019 11:29 am
Forum: Automation, sensing and robotics
Topic: Pi for mushroom grow room automation.
Replies: 2
Views: 560

Re: Pi for mushroom grow room automation.

If I help, do I get some mushrooms? :D What you want is easily feasible with the Pi, but I bet there are others here who can help more specifically than I can for your case (I'm still a newb to the Pi but have plenty of electronics background). However... That remote control socket is a great idea, ...
by NGC6543
Sat Apr 13, 2019 11:11 am
Forum: Raspbian
Topic: getting gps to work on raspberry pi 3
Replies: 23
Views: 2110

Re: getting gps to work on raspberry pi 3

│ Status: NO FIX (12 secs) ││ That might give a clue... I've no idea what you should see if you don't have a GPS fix in cgps, because I've never run it without one. I made sure I had a fix before all of that when I set up mine, by watching the cat output from the serial port. That makes life much e...
by NGC6543
Fri Apr 12, 2019 11:23 pm
Forum: Raspbian
Topic: getting gps to work on raspberry pi 3
Replies: 23
Views: 2110

Re: getting gps to work on raspberry pi 3

From a quick look at the schematic, it seems the PPS output isn't connected to the GPIO. It is on one of the jumpers on the board though, labelled 1PPS. You can connect it manually to a GPIO. Just check the schematic - pin 1 on the jumper is the PPS and the other pin is ground so connect the right o...
by NGC6543
Fri Apr 12, 2019 10:59 am
Forum: C/C++
Topic: Making sense of ADS-B checksums & bitfields
Replies: 52
Views: 5897

Re: Making sense of ADS-B checksums & bitfields

That mirrored collinear... is that similar to a Franklin antenna?

That's what I've been tempted to try making, although I've literally just started with this ADS-B stuff. I might as well put my amateur license (M0WZF) to some use too for once.
by NGC6543
Fri Apr 12, 2019 10:34 am
Forum: General discussion
Topic: Have a laugh at my quality antenna
Replies: 7
Views: 709

Re: Have a laugh at my quality antenna

Thanks, I'll take a look at that thread. I'm getting about 100 miles range; a few contacts beyond that but not much. Altitude is no problem up to 12km+. It might be a bit poorer because I'm in a valley as well. I'm at 300m above sea level but on the side on one hill, with higher ground all around me...
by NGC6543
Thu Apr 11, 2019 1:39 pm
Forum: General discussion
Topic: Run a pi3 on battery for a week ?
Replies: 7
Views: 592

Re: Run a pi3 on battery for a week ?

I typed this up while making coffee etc, and folks beat me to it. You can have it anyway... Have a look at these pages for some power consumption figures: https://raspi.tv/2018/how-much-power-does-raspberry-pi-3b-use-power-measurements https://www.pidramble.com/wiki/benchmarks/power-consumption Let'...
by NGC6543
Thu Apr 11, 2019 11:44 am
Forum: General discussion
Topic: Have a laugh at my quality antenna
Replies: 7
Views: 709

Have a laugh at my quality antenna

I noticed a few days ago people talking about ADS-B. I decided to give it a try on my Pi... at 3:00am because I couldn't sleep :lol: Usually, I don't bother making antennae. Life's too short and it's easier to just buy one that actually works as expected. Not at 3am though... so this is what I came ...
by NGC6543
Wed Apr 10, 2019 6:50 pm
Forum: Automation, sensing and robotics
Topic: 26 GPIO to drive 26 Optocoplers
Replies: 17
Views: 1536

Re: 26 GPIO to drive 26 Optocoplers

First, the optocouplers will only give a very small current through the output. Around 1.2 times the current you give the input LED, from the graph on the PC817 datasheet. It varies though. As to your use of Ohm's law, this is how it would be done for that optocoupler: Decide what current you want t...
by NGC6543
Tue Apr 09, 2019 1:52 pm
Forum: Beginners
Topic: Is 2.4A 5V not enough for pi 3 b+?
Replies: 17
Views: 1094

Re: Is 2.4A 5V not enough for pi 3 b+?

compnaion wrote:
Tue Apr 09, 2019 1:42 pm
That charger is too expensive it is like buying a 300$ charger for a phone that has a price of 1000$.
That charger is not a charger, it is a regulated power supply.
by NGC6543
Tue Apr 09, 2019 1:47 pm
Forum: Beginners
Topic: Is 2.4A 5V not enough for pi 3 b+?
Replies: 17
Views: 1094

Re: Is 2.4A 5V not enough for pi 3 b+?

It amazes me how many times this question comes up here since I joined a few weeks ago. But then, the first thing I tried to use was a proper, branded 2.5A phone charger. Low voltage warning instantly, :lol: Phone chargers are not power supplies - at best they have poorly regulated, approximate volt...
by NGC6543
Tue Apr 09, 2019 1:38 pm
Forum: Automation, sensing and robotics
Topic: 26 GPIO to drive 26 Optocoplers
Replies: 17
Views: 1536

Re: 26 GPIO to drive 26 Optocoplers

I agree with using port expanders on the SPI or I2C bus for that many outputs. That gets away from the current limit on the GPIO pins as well.
by NGC6543
Mon Apr 08, 2019 9:24 am
Forum: Beginners
Topic: Power supply
Replies: 8
Views: 572

Re: Power supply

When our cat was a kitten and teething (I guess), she chewed almost every mains wire in the house. I'm amazed she survived; some of the wires (like the one she found while hiding behind the washing machine) were chewed almost to shreds. I could see the copper shining though the holes! On topic... I ...
by NGC6543
Sun Apr 07, 2019 11:37 pm
Forum: Troubleshooting
Topic: WLAN MAC address changes at every reboot?
Replies: 21
Views: 2117

Re: WLAN MAC address changes at every reboot?

Assuming (dangerous, I know) that the (seemingly top secret) LAN7515 is similar to the LAN7500, the MAC address is either stored in an external EEPROM or is configured by the driver. I cannot see an EEPROM anywhere near the LAN7515, so in the absence of any other clues must assume it's done by the d...
by NGC6543
Sun Apr 07, 2019 6:53 pm
Forum: Raspbian
Topic: getting gps to work on raspberry pi 3
Replies: 23
Views: 2110

Re: getting gps to work on raspberry pi 3

OK.... Get a spare SD card, install Raspbian afresh, and start from scratch. Once you have the Pi running, run raspi-config and do the following: ..Go to the interfaces ....Select serial ......turn off the shell access ......leave the hardware enabled ..save and reboot. Then try my two lines from ab...
by NGC6543
Sun Apr 07, 2019 5:58 pm
Forum: Raspbian
Topic: getting gps to work on raspberry pi 3
Replies: 23
Views: 2110

Re: getting gps to work on raspberry pi 3

rpdom wrote:
Sun Apr 07, 2019 5:51 pm
They are both hardware UARTS.
Thanks for the correction :)

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