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by Mortimer
Wed Apr 17, 2019 9:35 am
Forum: Python
Topic: How to save GPS Data to a text file?
Replies: 11
Views: 153

Re: How to save GPS Data to a text file?

It probably relates to the OP's first port to the forum... https://www.raspberrypi.org/forums/viewtopic.php?f=32&t=234357&p=1433628#p1433628 They are probably still using an Adafruit Ultimate GPS Breakout. I assume by this question they have managed to get the GPS board working, if so it would have ...
by Mortimer
Sun Apr 14, 2019 10:52 am
Forum: Beginners
Topic: Convert NMEA sentence Lat and Lon to Decimal Degrees
Replies: 4
Views: 7914

Re: Convert NMEA sentence Lat and Lon to Decimal Degrees

My word! How silly of me. Amazing it stood for so long undetected! Corrected (for what it's worth): So... Lat : 3137.36664 becomes 31 degrees and 37.26664 seconds = 31 + 37.36664/60 = 31.6227773 Lon : 00212.21149 becomes 2 degrees and 12.21149 seconds = 2 + 12.21149/60 = 2.20352483 So as latitude is...
by Mortimer
Wed Mar 13, 2019 12:48 pm
Forum: Beginners
Topic: Electric pulse scanner
Replies: 8
Views: 318

Re: Electric pulse scanner

Yup, what Brandon said. With a new contact block for the switch available for only a handful of £'s (or €'s or $'s) it's a no brainer really. https://uk.rs-online.com/web/p/contact-blocks-light-blocks/3310473/ All that is left is whether or not you can legally modify the equipment, i.e. do local reg...
by Mortimer
Wed Feb 27, 2019 9:58 am
Forum: HATs and other add-ons
Topic: Motorola Lapdock Atrix with the Pi
Replies: 16
Views: 2932

Re: Motorola Lapdock Atrix with the Pi

I have an Atrix lapdock, and in my experience: RPi 2B worked reliably, powered from the lapdock, even without a USB power lead connected from the lapdock to the RPi power inlet. I.e. powered entirely via backfeed power down the USB data connection. However this only worked if using the USB socket on...
by Mortimer
Tue Feb 12, 2019 12:44 pm
Forum: Off topic discussion
Topic: Order a special request Raspberry Pi :?:
Replies: 68
Views: 3091

Re: Order a special request Raspberry Pi :?:

I was there at VMWorld 2018 in Las Vegas when they demonstrated ESXi running on a Raspberry Pi. At the time they stated that this wasn't done because the Raspberry Pi was a realistic platform to run a hypervisor, but because if they could get it running on a Pi then any ARM based board becomes a pos...
by Mortimer
Fri Feb 08, 2019 1:12 pm
Forum: Gaming
Topic: Commodore PET Mini
Replies: 11
Views: 663

Re: Commodore PET Mini

Looks interesting. I like the look of the website too, but I do wonder why the "What You'll Need" page has pink links for the item names, that simply link back to the top of the page rather than manufacturer or supplier pages for the items in question?
by Mortimer
Tue Feb 05, 2019 12:18 pm
Forum: Automation, sensing and robotics
Topic: Seeking guidance with powering motors
Replies: 19
Views: 666

Re: Seeking guidance with powering motors

Brushed motors connected in series is not ideal either. The current passing through a brushed motor is very choppy, and this passes through the next motor which adds its own choppiness and so on. They may turn, but I would expect torque at each motor to be way down on what it can do by itself on its...
by Mortimer
Wed Jan 23, 2019 2:54 pm
Forum: General discussion
Topic: Control Fan by switching USB port on and off
Replies: 22
Views: 831

Re: Control Fan by switching USB port on and off

You'll need snubbers on those motors, to 'snub' the back EMF from the motors when they are turned off. Otherwise you'll get voltage spikes going back into the 5V supply rail.

It might also be preferable for the 5V supply to come directly from the PSU, rather than via the RPi.
by Mortimer
Mon Jan 21, 2019 1:17 pm
Forum: Automation, sensing and robotics
Topic: 2 LED wiring
Replies: 11
Views: 468

Re: 2 LED wiring

You can use one resistor if only one LED will be on at a time . Anode of each LED to their GPIOs. Cathodes of LEDs and one end of resistor all joined together. Other end of resistor to ground. he wouldn't be able to use the circuit as shown even in those circumstances. The right hand LED is depicte...
by Mortimer
Tue Nov 27, 2018 1:31 pm
Forum: General discussion
Topic: Flyback Diodes - Solenoid Valves
Replies: 9
Views: 476

Re: Flyback Diodes - Solenoid Valves

If using a relay then I'd say there was little need for the flyback diode. The potential on one contact of the relay goes up, but that's not going to cause any grief (unless it could get high enough to arc). Surely there will be an arc between the relay contacts every time the contacts are opened (...
by Mortimer
Thu Nov 22, 2018 10:49 am
Forum: Troubleshooting
Topic: Try to run a Python script without luck...
Replies: 6
Views: 451

Re: Try to run a Python script without luck...

Alternatively, if you're using WinSCP to copy the file to the RPi, the conversion will be done there too, but you may need to make sure the transfer mode is set to "Text", or if it is set to "Automatic" that the "Transfer following files in text mode:" field contains the file extensions for the file...
by Mortimer
Thu Nov 22, 2018 10:17 am
Forum: Troubleshooting
Topic: Try to run a Python script without luck...
Replies: 6
Views: 451

Re: Try to run a Python script without luck...

Yup, had to do a similar thing just a few minutes ago whilst writing a shell script to run on an ESXi server in Notepad++. With the file open, select "Edit" > "EOL Conversion" > "Unix (LF)". I believe Notepad++ will remember that setting for the file, so it shouldn't be necessary to do that again fo...
by Mortimer
Thu Nov 22, 2018 10:09 am
Forum: Troubleshooting
Topic: relay or led - fluctuating
Replies: 7
Views: 1079

Re: relay or led - fluctuating

I wouldn't mind betting on the flowmeter actually accelerating when the gas is blasted through it. I reckon the impeller inside will spin much more freely in a gaseous flow, without the viscosity of the fluid to slow it down. So basically when the gas solenoid valve is opened until possible several ...
by Mortimer
Wed Nov 21, 2018 7:01 pm
Forum: Troubleshooting
Topic: relay or led - fluctuating
Replies: 7
Views: 1079

Re: relay or led - fluctuating

I guess - change the code to ignore the flowmeter pulses after the pour has completed.
by Mortimer
Wed Nov 21, 2018 11:30 am
Forum: Troubleshooting
Topic: relay or led - fluctuating
Replies: 7
Views: 1079

Re: relay or led - fluctuating

Does the flow meter stop spinning and sending pulses when the solenoid is turned off?

I suspect that it may be that when the solenoid closes and the liquid is drained past the flow sensor, the sensor spins for a few more seconds, giving you more counts than you expect.
by Mortimer
Tue Nov 20, 2018 6:48 am
Forum: Troubleshooting
Topic: relay or led - fluctuating
Replies: 7
Views: 1079

Re: relay or led - fluctuating

My guess based on what I can see here is that there is not enough power for the cleaning solenoid to open properly.

Does the program run correctly without the solenoid connected?
by Mortimer
Fri Nov 02, 2018 12:25 pm
Forum: Beginners
Topic: Detect current on Raspberry pi
Replies: 88
Views: 6329

Re: Detect current on Raspberry pi

So you think just turning the mic gain down will be enough?
by Mortimer
Thu Nov 01, 2018 8:41 pm
Forum: Beginners
Topic: Detect current on Raspberry pi
Replies: 88
Views: 6329

Re: Detect current on Raspberry pi

Then it doesn't look like you can re-create the phase-cancellation of the device in its native form using the USB sound dongle and RPi.

You might be able to find some software that will do the feedback cancellation for you, I don't know.
by Mortimer
Thu Nov 01, 2018 11:32 am
Forum: Beginners
Topic: Detect current on Raspberry pi
Replies: 88
Views: 6329

Re: Detect current on Raspberry pi

Hmm! the microphone might be polarised (is it an electret mic?). Try swapping the speaker wires instead.
by Mortimer
Wed Oct 31, 2018 11:04 pm
Forum: Beginners
Topic: Detect current on Raspberry pi
Replies: 88
Views: 6329

Re: Detect current on Raspberry pi

Because the audio circuitry of the handset by its self was carefully designed so that the microphone audio and speaker audio were 180 degrees out of phase and at an amplitude that any locally fed noise would cancel itself out. The audio circuitry of the USB audio dongle was likely in-phase and ther...
by Mortimer
Wed Oct 31, 2018 9:53 pm
Forum: Beginners
Topic: Detect current on Raspberry pi
Replies: 88
Views: 6329

Re: Detect current on Raspberry pi

Interesting, it sounds like it might be it but then I don't understand why this Larsen effect didn't occur at all without the Pi. Because the audio circuitry of the handset by its self was carefully designed so that the microphone audio and speaker audio were 180 degrees out of phase and at an ampl...
by Mortimer
Tue Oct 30, 2018 1:10 pm
Forum: Beginners
Topic: Detect current on Raspberry pi
Replies: 88
Views: 6329

Re: Detect current on Raspberry pi

Wouldn't it be easier to look for the signal that triggers the oscillator circuit driving the ringer speaker, because that will be a simple Voltage level change surely? Much easier to interface to a GPIO. If not : I would take the speaker feed, AC couple to a rectifier, and then a simple smoothing c...
by Mortimer
Fri Oct 19, 2018 11:01 am
Forum: General discussion
Topic: SD card write count?
Replies: 15
Views: 891

Re: SD card write count?

LOL! reminds me of the time way back when I was working in the avionics industry, we got in a bubble memory device to try out. Someone thought it a good idea to try it out as a hard-drive in a computer. I think it lasted less than an hour!

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