Go to advanced search

by aTao
Mon Apr 09, 2018 9:04 pm
Forum: General discussion
Topic: Is it possible to use cron to handle other cron
Replies: 7
Views: 554

Re: Is it possible to use cron to handle other cron

Sounds all a bit confoozled, and therefore prone to you not knowing why it has gone off and sat in a corner.
are you sure that you couldnt write a single cron job that reads the table and acts accordingly (as in do the job you were going to get the second cron to do)?
by aTao
Sat Mar 17, 2018 7:44 pm
Forum: Automation, sensing and robotics
Topic: different liquid detection using raspberry pi
Replies: 5
Views: 571

Re: different liquid detection using raspberry pi

It would help if we could see your circuit diagram. I see no reference to how you generate to voltage that you need to measure. The data sheet for the ADC indicates that the source impedance (your probes and glass of liquid) should be as near to 0 ohms as possible. You would need to first use the li...
by aTao
Sat Mar 03, 2018 8:48 pm
Forum: Beginners
Topic: Ring a church bell
Replies: 3
Views: 440

Re: Ring a church bell

as others have said, the programming is no problem, its the actuator thats the tricksy part. and that depends on the bell and existing mechanism. There are 2 types of bell mechanism, clocks and chimes (as in what bell ringers or campanologists to be fancy) pull on. The clock bell uses a hammer that ...
by aTao
Sun Feb 18, 2018 5:10 pm
Forum: Off topic discussion
Topic: How good is current AI ?
Replies: 15
Views: 2495

Re: How good is current AI ?

aTao, First, the Tesla that didnt see a truck. There isnt a human driver on this planet that wouldnt have seen the truck. Sure there are people that do crash into trucks they didnt see, but its because they werent concentrating, not because they didnt recognise it. So what? From a practical point o...
by aTao
Sun Feb 18, 2018 1:03 am
Forum: Off topic discussion
Topic: How good is current AI ?
Replies: 15
Views: 2495

Re: How good is current AI ?

Given that we dont yet know how a neuron works, modelling a learning machine on it is a bit barking up the wrong tree. The electrical signal is just one (possibly small and misunderstood) aspect, there is chemical signalling and physical signalling/ signal routing. The nano code for a supposed AI ma...
by aTao
Fri Feb 09, 2018 9:54 pm
Forum: Beginners
Topic: Using a Pi Zero W to detect a mains powered doorbell press
Replies: 8
Views: 1074

Re: Using a Pi Zero W to detect a mains powered doorbell press

Dont need bridge rectifier, a single diode doing half wave will do. Just put some signal debouncing in software (if you think you have over 50 bell presses per second, its probably 1 long press!) Apart from that, to take the circuit from 25Vac in to 15Vac then start with the resistor in the diagram ...
by aTao
Tue Jan 23, 2018 10:29 pm
Forum: General discussion
Topic: Voltage to Current board
Replies: 7
Views: 791

Re: Voltage to Current board

You can make (or easier still buy) voltage controlled current source http://www.linear.com/solutions/4475 for example. However, I'm not sure that it will solve the undelying problem of why the ball wont stay in the middle. I would suggest that you: A cheat (put a magnet under the plate) B examine yo...
by aTao
Thu Jan 18, 2018 6:48 pm
Forum: Beginners
Topic: Why Should I or Should Not Learn Scratch?
Replies: 4
Views: 468

Re: Why Should I or Should Not Learn Scratch?

At some point it is very useful to be able to learn any language, to understand the fundamental differences and how (and how not) to use them. But that is not necessarily a beginning. As mattmiller said if Python is going well, stick with it, if you have time and energy for another language Scratch ...
by aTao
Wed Jan 17, 2018 5:56 pm
Forum: Python
Topic: Fingerprint comparison
Replies: 9
Views: 1651

Re: Fingerprint comparison

The images are processed to generate a map of the print. Things like whorl, arch, loop, number of ridges between the whorl and any branches, how may loops before the next branch and the like.
by aTao
Mon Jan 08, 2018 4:10 pm
Forum: Automation, sensing and robotics
Topic: Homebrew Solution for Monitoring Heating Oil Levels
Replies: 1
Views: 394

Re: Homebrew Solution for Monitoring Heating Oil Levels

Oil consumption is very low (in litres per minute) so there is almost no pressure drop along the supply pipe to the boiler (in the house). So, to first avoid outdoor electronics and needing to run power out and data back: I would recommend a pressure sensor very close to the boiler. Ideally an I2s u...
by aTao
Sun Jan 07, 2018 8:42 pm
Forum: Troubleshooting
Topic: I think I damaged my SD card port in Pi 3
Replies: 2
Views: 265

Re: I think I damaged my SD card port in Pi 3

Bit of fluff in the socket??
by aTao
Sat Sep 02, 2017 9:07 pm
Forum: General programming discussion
Topic: Which language Python or Java or C++
Replies: 18
Views: 5040

Re: Which language Python or Java or C++

Power measurement ic with I2c connection: MAXQ314
I2c bi directional isolator ISO1540

read the power just as often as you can.
by aTao
Sun Aug 27, 2017 9:14 pm
Forum: General programming discussion
Topic: Which language Python or Java or C++
Replies: 18
Views: 5040

Re: Which language Python or Java or C++

OK, so forget RMS (for now) and consider what you want to measure. For energy monitoring you want to measure power used, and that isnt going to change at 50Hz, is it? If you do a bit of analog electronic pre processing you can get your sample rate down to something mush more manageable. Say each cha...
by aTao
Tue Aug 08, 2017 10:41 am
Forum: Troubleshooting
Topic: Magnet - degaussing coil - ruined Pi Zero?
Replies: 7
Views: 1050

Re: Magnet - degaussing coil - ruined Pi Zero?

drgeoff wrote:
Mon Aug 07, 2017 9:45 pm
delousing?
Yeah, a magnetised telly has a lousy picture.
by aTao
Mon Aug 07, 2017 9:18 pm
Forum: Troubleshooting
Topic: Magnet - degaussing coil - ruined Pi Zero?
Replies: 7
Views: 1050

Re: Magnet - degaussing coil - ruined Pi Zero?

A delousing wand needs to project its magnetic field well beyond itself in order to delouse the equipment. Monitors with inbuilt delousing (on start-up) dont project anywhere nears as much since the delousing coil is right next to the parts that need it. Also, the circuit in CRT display need to with...
by aTao
Sun Aug 06, 2017 11:24 pm
Forum: General discussion
Topic: Cycling Sensors for Cycling Computer
Replies: 19
Views: 3505

Re: Cycling Sensors for Cycling Computer

No, you cant! The outer edge of a bicycle tyre is not a circle, and you will not measure its diameter that accurately. You know that, I know that. But it's a pain to mark a straight line, mark a point on the tyre where it touches the road, move the bike along the line until the point on the tyre to...
by aTao
Sun Aug 06, 2017 7:39 pm
Forum: General discussion
Topic: Cycling Sensors for Cycling Computer
Replies: 19
Views: 3505

Re: Cycling Sensors for Cycling Computer

Use a hall-effect sensor with a magnet on a spoke. You can then use wheel size and 3.141592 (π) to determine how far you've moved in one revolution. https://www.sheldonbrown.com/cyclecomputer-calibration.html gives 2097mm for my 700*23c road wheels. No, you cant! The outer edge of a bicycle tyre is...
by aTao
Tue Aug 01, 2017 9:11 pm
Forum: Networking and servers
Topic: How to create a web server for actual GPS data
Replies: 2
Views: 871

Re: How to create a web server for actual GPS data

GPS devices can be accessed through a file in /dev/ probably ttyACM0 (have a look at the directory , unplug GPS have another look and see which file vanishes). This file when read will give the latest NMEA sentence from the GPS device, some of these contain the position information. So, write a serv...
by aTao
Mon Jul 31, 2017 6:41 pm
Forum: Troubleshooting
Topic: Composite: Video being output on both red and yellow pins
Replies: 13
Views: 1498

Re: Composite: Video being output on both red and yellow pins

Yes, I'm using a Known Good Cable (KGC) that I tested on my cable box. I have a portable DVD player that has a 3.5mm A/V in and the KGC works flawlessly there. What Imperf3kt mean was that here are different standard connections for an AV 3.5mm jack... see https://www.element14.com/community/thread...
by aTao
Mon Jul 31, 2017 4:34 am
Forum: Troubleshooting
Topic: Composite: Video being output on both red and yellow pins
Replies: 13
Views: 1498

Re: Composite: Video being output on both red and yellow pins

Are you sure its the correct wiring? Not all 3.5mm to RCA cables are the same. Your issue sounds like the ground or another signal is on the wrong pin. Yes, I'm using a Known Good Cable (KGC) that I tested on my cable box. I have a portable DVD player that has a 3.5mm A/V in and the KGC works flawl...
by aTao
Sun Jul 30, 2017 4:55 pm
Forum: General discussion
Topic: Making an underwater device with raspberry pi 3 and need help !
Replies: 4
Views: 817

Re: Making an underwater device with raspberry pi 3 and need help !

Hi, The idea of the device is that it should be able to record the depth of a dive, not more than 40 meters, and the time spent at the different underwater levels. It should also be able to record the temperature. Ideally, it should record all the data and once it is outside of the water, to be syn...
by aTao
Sun Jul 30, 2017 5:04 am
Forum: General discussion
Topic: Making an underwater device with raspberry pi 3 and need help !
Replies: 4
Views: 817

Re: Making an underwater device with raspberry pi 3 and need help !

what depth? how long will it be under water?
by aTao
Fri Jul 28, 2017 8:11 am
Forum: Compute Module
Topic: Soldering under the CM3
Replies: 4
Views: 1286

Re: Soldering under the CM3

For a 1 off, or bespoke build, then its ok, provided you check the height of the wire stub (if poked though from other side) or wire height (if poike through from top side) after soldering. In a production situation this would be an expensive nuisance. You might test your idea by assembling one and ...
by aTao
Sat Jul 22, 2017 5:15 am
Forum: General discussion
Topic: GCSE - Burglar Alarm
Replies: 4
Views: 644

Re: GCSE - Burglar Alarm

GingerBondy007 wrote:Thanks, Its a Pi 3. Do I need to solder the female connecter in a certain direction, i.e. does it have a notch? If it doesn't, does that mean that I can solder it on any way. Thanks.
No notch and, even if there was, there is nothing on the RPi3 to prevent plugging it in the wrong way.
by aTao
Fri Jul 21, 2017 9:16 pm
Forum: General discussion
Topic: GCSE - Burglar Alarm
Replies: 4
Views: 644

Re: GCSE - Burglar Alarm

Solder one of: https://electronic-things.co.uk/product/condilf40/?attribute_quantity=pack-of-5&gclid=CjwKCAjwzMbLBRBzEiwAfFz4gaETth3rAsvoqr3m_hfOvDkfu44HfhNGLJbGYvwFkLNfDvKhE-iaARoC8y8QAvD_BwE https://electronic-things.co.uk/wp-content/uploads/2014/07/CON-PCB-F40P-DIL-01B.jpg To the bottom of your PCB

Go to advanced search