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by btidey
Tue Oct 08, 2019 8:17 am
Forum: Automation, sensing and robotics
Topic: Looking for a relatively low-cost electrical conductivity sensor that gives the signal in digital output
Replies: 5
Views: 259

Re: Looking for a relatively low-cost electrical conductivity sensor that gives the signal in digital output

You need to give a bit more info to get some suggestions. What type of material are you trying to measure; liquid, solid? What range of conductivity are you trying to measure? What accuracy are you trying to achieve? Conductivity is normally measured by sensing the current flow across a known geomet...
by btidey
Mon Oct 07, 2019 8:05 am
Forum: Automation, sensing and robotics
Topic: Dimming fluorescent lights
Replies: 13
Views: 581

Re: Dimming fluorescent lights

To get a more linear response you could use a simple look up table to translate the desired dim power into the value of PWM needed. You might also want to play around with the pwm set up. Higher frequency is good to ensure the capacitor smooths out the signal to avoid flicker but also reduces the re...
by btidey
Sun Oct 06, 2019 8:22 pm
Forum: Automation, sensing and robotics
Topic: Dimming fluorescent lights
Replies: 13
Views: 581

Re: Dimming fluorescent lights

Looking at the picture it seems the 470 resistor is shorted out the same way as you had on the input. That would mean even a low value of pwm would discharge the capacitor very quickly as the opto transistor turns on leading to the low voltages you see. Try correcting that. The value of the 470 resi...
by btidey
Sun Oct 06, 2019 9:48 am
Forum: Automation, sensing and robotics
Topic: Dimming fluorescent lights
Replies: 13
Views: 581

Re: Dimming fluorescent lights

Few things. 1. Keep PWM frequency as high as possible. This is second parameter of IO.PWM. Maybe use 2000. 2. I would leave the 100K value. That should set maximum brightness when PWM is 0. 3. Sounds like PWM is not getting through for some reason. You can do a first level check by monitoring the vo...
by btidey
Thu Oct 03, 2019 9:16 pm
Forum: Automation, sensing and robotics
Topic: Dimming fluorescent lights
Replies: 13
Views: 581

Re: Dimming fluorescent lights

I thought about using the op-amp approach but the snag is that the + is not really a voltage supply so you need a separate 10V power supply and then it states that one should isolate the output from the micro-controller which makes it tricky. The servo approach would work fine and provides isolation...
by btidey
Thu Oct 03, 2019 11:55 am
Forum: Automation, sensing and robotics
Topic: Dimming fluorescent lights
Replies: 13
Views: 581

Re: Dimming fluorescent lights

I don't think a digital potentiometer is the best method here. The 10V interface is actually more like a current sink interface. The + is a supply voltage fed through a resistor, The analog potentiometer from here to - means that the voltage at the + will drop as the potentiometer is reduced in valu...
by btidey
Sun Sep 08, 2019 8:00 am
Forum: Automation, sensing and robotics
Topic: safe protocol for cheap 433MHz transceiver
Replies: 8
Views: 439

Re: safe protocol for cheap 433MHz transceiver

Depending on what your PIC is doing another thought would be to replace that with a wifi module like an ESP8266 based unit (Wemos D1 or ESP-12F). The ESP8266 can do most things a PIC can do. The wifi range is very good without external aerials; the processor is fast; the modules are very cheap; and ...
by btidey
Mon Aug 12, 2019 8:26 am
Forum: Automation, sensing and robotics
Topic: Anyone built successfully RF receiver and transmitter on pi3
Replies: 3
Views: 916

Re: Anyone built successfully RF receiver and transmitter on pi3

You really do need an antenna on both receiver and transmitter. You can get pre-wound little coil antennae which are OK or a straight 17cm wire will work OK. Stick with the second superhet receiver. They are much better than the regnerative type in the first link. Verify that your curtain remote is ...
by btidey
Fri Jul 05, 2019 6:42 pm
Forum: Camera board
Topic: RPi Cam Web Interface
Replies: 5063
Views: 1323003

Re: RPi Cam Web Interface

Any timeline as to when the installation script will be updated to take into account the new Buster build? Just installed RPi Cam on Buster, no problems, weirdly it will not now install on Jessie!!! The script now calls for php7.3 to be installed this is not available on earlier versions, if you lo...
by btidey
Fri Apr 19, 2019 3:23 pm
Forum: Automation, sensing and robotics
Topic: Can a power line provide Raspberry Pi and a lamp with power?
Replies: 16
Views: 1056

Re: Can a power line provide Raspberry Pi and a lamp with power?

I know there have been lots of articles about neat wifi 6 features helping IoT but ... ax is not even ratified yet, (Q3 2019?) some pre-ratification products are only just starting to appear (Samsung 10), and your router will need an upgrade. A lot of IOT is quite usable today without the extra feat...
by btidey
Fri Apr 19, 2019 7:55 am
Forum: Automation, sensing and robotics
Topic: Voltage Datalogger (please help out a noob)
Replies: 6
Views: 671

Re: Voltage Datalogger (please help out a noob)

One idea to remove the problem of hazardous working is to use a plug in AC-AC power adapter that gives out a low voltage like 5V. It is important that it is AC output as that will be just an isolation transformer and not a regulated dc supply. It is also important to get one with a safety certificat...
by btidey
Thu Apr 11, 2019 7:06 am
Forum: General discussion
Topic: Use a Potentiometer to control sound.
Replies: 5
Views: 305

Re: Use a Potentiometer to control sound.

If you want a rotary control for the volume then consider using a rotary encoder instead of a potentiometer. An encoder can connect to a couple of GPIO pins and then rotation can be detected and turned into a 'value to control the volume digitally. Rotary encoders do not have an absolute position bu...
by btidey
Fri Mar 15, 2019 9:32 am
Forum: Beginners
Topic: Why my IR LED transmitter not transmit any signal?
Replies: 43
Views: 1980

Re: Why my IR LED transmitter not transmit any signal?

The original circuit is bad There is nothing specifically to limit the current drawn through the two diodes and the transistor. The voltage drop across an IR LED is about 1.5V so with 2 in series and a 5V supply the current will be determined just by the gain of the transistor and the capacity of th...
by btidey
Fri Mar 01, 2019 9:11 am
Forum: General discussion
Topic: Need an outdoor case for a security camera
Replies: 13
Views: 1239

Re: Need an outdoor case for a security camera

I want it to look like a CCTV camera though, because it's a visible deterrant. The original project I followed was here https://www.raspberrypi.org/blog/turn-your-pi-into-a-low-cost-hd-surveillance-cam/ however the dummy one suggested here is too small for the Pi3 (which has the micro USB power in ...
by btidey
Thu Feb 28, 2019 11:26 am
Forum: General discussion
Topic: Need an outdoor case for a security camera
Replies: 13
Views: 1239

Re: Need an outdoor case for a security camera

I think this one https://cpc.farnell.com/haydon/hay-772city/dummy-camera-external/dp/SR07209?MER=sy-me-pd-mi-alte would be big enough, but it's a pretty solid unit and expensive. This one also looks a possible https://www.ebay.co.uk/itm/Dummy-Security-CCTV-Camera-Quality-Aluminium-Fully-Weather-Proo...
by btidey
Thu Feb 07, 2019 9:20 am
Forum: General discussion
Topic: Does Raspberry Pi have enough power to control 50 LED's?
Replies: 6
Views: 385

Re: Does Raspberry Pi have enough power to control 50 LED's?

With that number of LEDs you should check out using WS2812B pixel LEDs. A single GPIO pin can control a whole string as they are wired in series. Each LED can be independently faded and have its colour set as each one is RGB. These LEDs are available as strips, circles, arrays or as individual dots....
by btidey
Tue Feb 05, 2019 8:46 am
Forum: Automation, sensing and robotics
Topic: understanding Alexa and Google assistant
Replies: 4
Views: 510

Re: understanding Alexa and Google assistant

Google search for control raspberry with Alexa. You will find lots of tutorials and projects on sites like instructables.
by btidey
Tue Feb 05, 2019 8:38 am
Forum: Beginners
Topic: port forwarding and linking to an already owned domain
Replies: 3
Views: 332

Re: port forwarding and linking to an already owned domain

I originally had an older model Verizon FIOS router with port forwarding working, but it broke and got replaced by a newer model where port forwarding seemed to be non-functional. This was not a problem for me as I already had a router behind this (running Tomato software) to give better wifi covera...
by btidey
Sun Jan 27, 2019 1:10 pm
Forum: Automation, sensing and robotics
Topic: understanding Alexa and Google assistant
Replies: 4
Views: 510

Re: understanding Alexa and Google assistant

There are many books on Alexa but most focus on using the service rather than understanding how it works. The Dummy books are quite good. There is no simple answer to your question on protocols, commands etc. as it varies according to what you are doing. Essentially there is a potentially a long pip...
by btidey
Fri Jan 11, 2019 8:39 am
Forum: Automation, sensing and robotics
Topic: 433Mhz Reciever for existing devices
Replies: 23
Views: 29672

Re: 433Mhz Reciever for existing devices

By the way, I also tried to run the same library and the python "rpi-rf" library on a Rasberry Pi 3, but receiving signals seams to be much worse compared to the Arduino. (Using the same receiver hardware) The rc-switch code only detects the signal about every 30 seconds instead of every second and...
by btidey
Wed Jan 09, 2019 9:44 pm
Forum: Automation, sensing and robotics
Topic: 433Mhz Reciever for existing devices
Replies: 23
Views: 29672

Re: 433Mhz Reciever for existing devices

Yes. That sounds promising. 1963815 is the decimal equivalent of 0x1DF727 which is what I though t the message was. I am not familiar with how that config works but I guess it is definitions are base clock period and then how header 0 and 1 are made up. So 1,2 (700/1400 for a zero and 700/2800 for a...
by btidey
Wed Jan 09, 2019 9:26 am
Forum: Automation, sensing and robotics
Topic: 433Mhz Reciever for existing devices
Replies: 23
Views: 29672

Re: 433Mhz Reciever for existing devices

The message is repeated twice in your sequence and is consistent each time. It looks to me like the basic structure is Leading sync consisting or 8ms on, 1msec off The following pulses are either 760uSec, 1420 uSec, or 2760uSec. There can be some timing distortion reading pulses so lets call these 7...
by btidey
Mon Dec 24, 2018 9:32 am
Forum: Automation, sensing and robotics
Topic: 433Mhz Reciever for existing devices
Replies: 23
Views: 29672

Re: 433Mhz Reciever for existing devices

It is common to use 433MHz to transmit data from stations like this, but no guarantees. You can check this out by using a low cost usb dvb-t tv stick as a spectrum analyser. See https://www.rtl-sdr.com/ Establishing the frequency of transmission is just the first step. You then have to work out how ...
by btidey
Wed Dec 05, 2018 9:26 am
Forum: General discussion
Topic: How to read weather station sensor over 433MHz?
Replies: 17
Views: 3310

Re: How to read weather station sensor over 433MHz?

I think you will need to vary the temp and humidity a bit around the sensor to see how the data changes Maybe something like first part is a fixed address followed by select address bits and then data/ Taking the bit encoding you suggest then from bit 17 onwards the nibbles are 0E631 If the first 3 ...
by btidey
Fri Nov 30, 2018 8:58 am
Forum: Automation, sensing and robotics
Topic: 433Mhz Reciever for existing devices
Replies: 23
Views: 29672

Re: 433Mhz Reciever for existing devices

There are 2 basic types of receivers; super-regenerative and super-heterodyne. The first sort is like the first type you posted. They are very cheap but also tend to have poor range. The superhet types have better range and are more stable. They are not significantly more expensive. Search for RXB6 ...

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