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by stevend
Sat Feb 08, 2020 7:30 pm
Forum: Automation, sensing and robotics
Topic: voltage sensing relay
Replies: 4
Views: 226

Re: voltage sensing relay

jjohnston7 wrote:
Fri Feb 07, 2020 7:03 pm
OH something like this? https://www.amazon.com/gp/product/B07HH ... LEZQ&psc=1
That's exactly the sort of thing I had in mind if you didn't need to get clever with the processing.
by stevend
Thu Feb 06, 2020 9:25 pm
Forum: Automation, sensing and robotics
Topic: voltage sensing relay
Replies: 4
Views: 226

Re: voltage sensing relay

Hi everyone, I'm very new to this, and am debating getting a raspberry pi if it will do what I need it to do. if you all could suggest part numbers with your replies that would be helpful too... I have 5 sensors that send a constant 5v signal. when the sensor is tripped, the voltage cuts down to 2....
by stevend
Thu Jan 30, 2020 9:27 pm
Forum: Automation, sensing and robotics
Topic: Peaceview PZEM-004T Energy Module
Replies: 44
Views: 23085

Re: Peaceview PZEM-004T Energy Module

Does anyone know if the pzem-004T (or the pzem 004) can indicate current flow direction, either on the display of through the comms interface? I have pv solar cells installed and want a setup that will give details of whether I’m importing or exporting power to the grid. These meters are designed t...
by stevend
Sun Jan 12, 2020 10:58 pm
Forum: General discussion
Topic: Setup local repository.
Replies: 3
Views: 232

Re: Setup local repository.

Not actually for Rasbian yet, but for another Linux OS I have a computer assigned as a repository, which is configured to mirror the complete master repository nightly. (Using rsync, so only the changes are downloaded). Configure your local repository to make it available on your local network (usin...
by stevend
Sun Jan 12, 2020 6:14 pm
Forum: General discussion
Topic: Weather Fax - need hardware advice
Replies: 7
Views: 389

Re: Weather Fax - need hardware advice

jbudd wrote:
Sun Jan 12, 2020 5:56 pm
Over in England we have the Metrological Office and BBC to forecast the weather for us but it's dumbed down so far. When I feel the need for proper weather maps I look to the USAF!
Have you found http://www.metbrief.com/charts.html - they do synoptic charts .
by stevend
Sun Jan 12, 2020 8:05 am
Forum: Automation, sensing and robotics
Topic: Pi somehow control wifi light dimmer ?
Replies: 11
Views: 784

Re: Pi somehow control wifi light dimmer ?

neilgl wrote:
Fri Jan 10, 2020 4:53 pm
+1 for Tasmota, though I programmed my Teckin smart switches without physically opening them.
Be careful if buying Teckin; they've made some changes which make them at best less useful, at worst useless for the likes of us.
by stevend
Fri Jan 10, 2020 11:16 pm
Forum: Automation, sensing and robotics
Topic: Peaceview PZEM-004T Energy Module
Replies: 44
Views: 23085

Re: Peaceview PZEM-004T Energy Module

Hi all, i know there is the v3 version that use modbus protocol over ttl, so a ttl to usb converter dongle is needed to connect it to a raspberry. But what is needed to connect more than one PZEM to that dongle? Is it possible? I would like to connect 6 or 9 PZEM (for a three phase system) to a ras...
by stevend
Sun Dec 22, 2019 7:27 pm
Forum: Automation, sensing and robotics
Topic: radiator valve head hacking
Replies: 26
Views: 1018

Re: radiator valve head hacking

Yes, looks OK - but might be affected by the operational mode set for the valve.

(I normally use the valves in timed mode, so the demand temperature is set according to the time of day).
by stevend
Fri Dec 20, 2019 8:23 pm
Forum: Automation, sensing and robotics
Topic: radiator valve head hacking
Replies: 26
Views: 1018

Re: radiator valve head hacking

i think i got all info i need, except what serial commands to send i looked at https://github.com/OpenHR20/OpenHR20/blob/master/rfmsrc/OpenHR20/com.c but that did not tell me anything Look at the files from the source code you downloaded - otherwise you'll confuse yourself. They will definitely be ...
by stevend
Fri Dec 20, 2019 1:52 pm
Forum: Automation, sensing and robotics
Topic: radiator valve head hacking
Replies: 26
Views: 1018

Re: radiator valve head hacking

Until this topic came up, I hadn't really realised that it was over 6 years ago that I started on this! And the software I'm running now probably wouldn't be recognised by the original author. Don't think I've looked at my software for 2-3 years now. But yes, looks as if you can select RS-232 mode w...
by stevend
Fri Dec 20, 2019 9:06 am
Forum: Automation, sensing and robotics
Topic: radiator valve head hacking
Replies: 26
Views: 1018

Re: radiator valve head hacking

What you need to appreciate is that there are two (at least) versions or the HR20 project. The 'original', which is the one available on Sourceforge, assumes you are using an RF module for communication. This is not what you want. 'My' version uses a hardware serial port, and is only available throu...
by stevend
Thu Dec 19, 2019 6:14 pm
Forum: Automation, sensing and robotics
Topic: radiator valve head hacking
Replies: 26
Views: 1018

Re: radiator valve head hacking

hmm... you might be on to something, my reason for using the ones from conrad was that i have 8 of them and i hate to trash something if i can reuse it I'm like that too; it's why I have a large number of boxes of items "awaiting redeployment". https://www.ebay.de/itm/Elektronischer-Heizkorperregle...
by stevend
Thu Dec 19, 2019 4:49 pm
Forum: Automation, sensing and robotics
Topic: radiator valve head hacking
Replies: 26
Views: 1018

Re: radiator valve head hacking

To answer your original question, this is a task possibly not well suited to the Pi. You need to set up a timer with a short timeout (just longer than the time between consecutive pulses) which you retrigger each time you receive a pulse. When you get a timeout, the pulses have stopped, so you stop ...
by stevend
Wed Nov 27, 2019 10:57 pm
Forum: Other projects
Topic: Custom RPI Music Reader for playing piano
Replies: 2
Views: 603

Re: Custom RPI Music Reader for playing piano

Have a look at this project:
https://www.leferguson.com/musicalpi-source-code/ (there are several blog posts about it, and a forum thread here somewhere)
Code is at: https://github.com/Linwood-F/MusicalPi
by stevend
Thu Oct 24, 2019 12:21 pm
Forum: Automation, sensing and robotics
Topic: Automatic Gate Using Rpi
Replies: 8
Views: 7335

Re: Automatic Gate Using Rpi

Some (most?) gate controllers have one or more external inputs to which you can connect buttons for open/close etc. So you can have a hard-wired button in the house to open the gate, for example (useful when the battery in the remote goes flat!). This may also give you more control options than goin...
by stevend
Sat Oct 19, 2019 11:50 am
Forum: General discussion
Topic: Choosing the correct output type in wind sensor module
Replies: 5
Views: 452

Re: Choosing the correct output type in wind sensor module

RS-485 is a multi-drop differential transmission system. You can have multiple transmitters on a bus, with just one at a time having its output enabled. Two wires are used to send a signal; both are driven; one to 0V, and another to positive voltage (typically 3-5V). The receiver measures the voltag...
by stevend
Sun Oct 13, 2019 3:46 pm
Forum: Automation, sensing and robotics
Topic: Is there an i/c? GPIO-controlled spdf-like switch to switch between 2 methods of controlling a transistor?
Replies: 3
Views: 1276

Re: Is there an i/c? GPIO-controlled spdf-like switch to switch between 2 methods of controlling a transistor?

You can make the LDR-based switch less "noisy" by using a comparator-type circuit with some added hysteresis. Probably the simplest way is to use a digital chip of the 74HCT14 type. In simple terms, if its input starts at 0V, as the voltage level increases through (say) 1.6 volts, the output will ch...
by stevend
Sat Sep 07, 2019 8:31 pm
Forum: Automation, sensing and robotics
Topic: safe protocol for cheap 433MHz transceiver
Replies: 8
Views: 783

Re: safe protocol for cheap 433MHz transceiver

At one level the transmission medium is irrelevant. So exclude the 433MHz bit from your searches. It's quite possible that Joan's suggestion of VirtualWire is all you need (look closely at the detail to see how it works, and whether it handles errors sufficiently well for you). Otherwise, if you hav...
by stevend
Sun Jul 28, 2019 9:59 pm
Forum: Off topic discussion
Topic: big hands
Replies: 9
Views: 2978

Re: big hands

Try searching for "screw gripper" Examples: https://uk.rs-online.com/web/p/screwdrivers/0547975/ https://www.kctoolco.com/wera-073680-screw-gripper-attachment-set-for-insulated-screwdrivers/ https://www.amazon.com/Felo-0715750078-Phillips-Screwdriver-Gripper/dp/B000E60ODS/ref=sr_1_3?keywords=Screw+G...
by stevend
Tue Jan 01, 2019 8:46 pm
Forum: Automation, sensing and robotics
Topic: Relay Line out voltage causing voltage on line in
Replies: 31
Views: 2712

Re: Relay Line out voltage causing voltage on line in

I think I have a problem with voltage noise passing between supposedly isolated parts of a relay & don't know how to get rid of it. I have recently bought a standard 5V relay module board (8-channel)* and can control it without issue using an mcp23017 connected to the pi (3). However, when I connec...
by stevend
Thu Dec 20, 2018 9:42 pm
Forum: Automation, sensing and robotics
Topic: Maximum switch count/current
Replies: 5
Views: 1900

Re: Maximum switch count

of course you could always 47K and 68K resistor which would reduce the current by a factor of 10 I'd recommend sticking to the values pcmanbob initially suggested (or, at least, around those values - maybe even slightly lower values, as long as you keep the ratio the same). They are the same order ...
by stevend
Sun Dec 16, 2018 8:34 am
Forum: Automation, sensing and robotics
Topic: DS18B20 randomly missing connection
Replies: 3
Views: 982

Re: DS18B20 randomly missing connection

I suspect the cable length is a bit long for a simple pullup; especially the star configuration. You could try rewiring all the sensors in a 'daisy chain' along one piece of wire, and if the wiring permits you could split the pullup resistor into two higher value resistors, with one at the Pi and th...
by stevend
Sun Dec 16, 2018 8:28 am
Forum: Off topic discussion
Topic: Why Avoid BASIC on RPi?
Replies: 2312
Views: 144864

Re: Why Avoid BASIC on RPi?

.... and there is no longer any need to try and force code into a smallest memory footprint. What about small embedded systems? (Things like the small AVRs, small ST32 family - these have as little as a few kilobytes of program memory, and a kilobyte or less of RAM). Sometimes the driver for using ...
by stevend
Sat Dec 01, 2018 7:32 pm
Forum: Automation, sensing and robotics
Topic: Tradfri light sunset switch on
Replies: 1
Views: 1404

Re: Tradfri light sunset switch on

If you don't want to be reliant on a working internet connection, its possible to calculate sunrise/sunset yourself. See: https://stackoverflow.com/questions/19615350/calculate-sunrise-and-sunset-times-for-a-given-gps-coordinate-within-postgresql I've attached the variant of the code from that link ...
by stevend
Sun Nov 25, 2018 8:42 pm
Forum: Off topic discussion
Topic: Why Avoid BASIC on RPi?
Replies: 2312
Views: 144864

Re: Why Avoid BASIC on RPi?

There was the BDSC C compiler by Leor Zolman for CP/M. That required a full up 64K machine I think. There was Tiny Pascal for the TRS-80. There was a standards-compliant Pascal Compiler for the Z-80 by a small British company called Prospero Software - ran under CP/M. Very good quality, with the ab...

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