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by JohnsUPS
Tue Apr 16, 2019 12:24 pm
Forum: General discussion
Topic: Powering RPI 3B+ With 24VAC
Replies: 17
Views: 500

Re: Powering RPI 3B+ With 24VAC

You also want to keep in mind that in addition to powering the Pi, this power supply will also be actuating solenoids to control water flow. When a (or multiple) solenoids are actuated, there is the possibility of the supply voltage being dragged down, which may interrupt the Pi. Just be aware that ...
by JohnsUPS
Mon Apr 15, 2019 1:15 pm
Forum: Automation, sensing and robotics
Topic: CT Sensor not working on home AC Feed
Replies: 5
Views: 147

Re: CT Sensor not working on home AC Feed

Hi all, I've been working on getting a CT sensor to work for a couple of weeks now. I've been doing my testing with a standard 13A kettle lead and have separated the live, neutral and earth - putting the clamp around the live wire. This has worked fine and I've got some accurate, calibrated reading...
by JohnsUPS
Mon Apr 15, 2019 1:59 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: interface with digital calipers
Replies: 52
Views: 8480

Re: interface with digital calipers

I like the look of that. An RPI with a big monitor and some extra functionality like relative positions etc would finish it off .. Oh and maybe a box or tow but then half my stuff never actually makes it in to a proper housing... In the finished Arduino version, there are buttons to set each calipe...
by JohnsUPS
Sat Apr 13, 2019 11:09 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: interface with digital calipers
Replies: 52
Views: 8480

Re: interface with digital calipers

OK....now I'm just going to have to do this with a Pi. Besides an electronics workshop, I also have a small machine shop. I affixed calipers to my mill and one of the lathes. The great thing about this is that there is zero backlash. Of course I wanted remote displays, so I used an Arduino. I should...
by JohnsUPS
Thu Apr 11, 2019 1:09 pm
Forum: Automation, sensing and robotics
Topic: DS18B20 network issues after 2 months stable
Replies: 5
Views: 163

Re: DS18B20 network issues after 2 months stable

I would advise against a loop of any sort. Instead, consider stringing them all out along a single length of cable. You're showing ~58m of cable, which should not pose a problem if wired correctly. Consider wiring in a small capacitor at each sensor to see if that improves anything.
by JohnsUPS
Wed Apr 10, 2019 11:52 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Detecting AC current using DC transformer
Replies: 4
Views: 310

Re: Detecting AC current using DC transformer

I need to monitor a float in a water tank. The float acts as a switch in a 120V AC circuit; when the water level falls below a specified level, the float switch closes and activates a contactor (relay) in the pump house that turns the well pump on. When the water level rises above a set level, it s...
by JohnsUPS
Mon Apr 08, 2019 11:06 pm
Forum: Off topic discussion
Topic: Learning Electronics
Replies: 56
Views: 1644

Re: Learning Electronics

Do try to keep up though. TAOE is now on it's 3rd edition: https://artofelectronics.net/ Oops....I was thinking the silver edition was the first....should have looked behind me on the shelf and checked the revision #. I bought the third edition as soon as I saw it.... I think most people only make ...
by JohnsUPS
Mon Apr 08, 2019 10:26 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: DS18B20 Max Distance
Replies: 41
Views: 41239

Re: DS18B20 Max Distance

Frank, I'm sure that a Pi could be configured to set the outputs to a known state upon booting up. If the sprinkler valves are solenoid operated, I suspect (correct me if I'm wrong) they would shut off by default upon a power loss. Also upon booting, you could have the Pi run a routine to take inven...
by JohnsUPS
Mon Apr 08, 2019 1:30 am
Forum: Automation, sensing and robotics
Topic: Wiring relay to Pi
Replies: 27
Views: 766

Re: Wiring relay to Pi

Consider a different opto.
My go-to opto is the MCT62.
by JohnsUPS
Sun Apr 07, 2019 4:18 am
Forum: Off topic discussion
Topic: Learning Electronics
Replies: 56
Views: 1644

Re: Learning Electronics

Wow, this thread takes me back. I also built a crystal radio on a small board. Mom wasn't happy when I nailed it to the bedpost so I could listen to the radio at night. Stringing the long antenna wire from the upstairs window was met with a similar reaction. At some point had one of those project ki...
by JohnsUPS
Sun Apr 07, 2019 3:50 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: DS18B20 Max Distance
Replies: 41
Views: 41239

Re: DS18B20 Max Distance

Hi all, I have been following this thread for quite some time. I have been working on building a solar hot water heater controller. I thought I found a solution until this evening. I ended up buying a 1-wire Add On board for a PiZero to use for the Solar Hot Water Controller. I had it all up and ru...
by JohnsUPS
Sun Apr 07, 2019 2:28 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Soldering the USB port - does not work
Replies: 16
Views: 463

Re: Soldering the USB port - does not work

Should I try to solder them directly to the pin for the port and not to the PPs? Could that make it better? Yes - I second that. If soldered directly to where the pins from the USB connector protrude through the board, there is no reason why that shouldn't work. Prior to soldering to the PP's (or d...
by JohnsUPS
Sun Apr 07, 2019 2:08 am
Forum: Automation, sensing and robotics
Topic: Mechanical unit automation
Replies: 7
Views: 310

Re: Mechanical unit automation

Hello folks. Not sure if I'm posting in the right area but here it goes. The company I work for is looking to use the raspberry pi in one of our projects. We essentially need to cut off power to a mechanical unit during predetermined times. We would need to have a calendar schedule of some sorts to...
by JohnsUPS
Sat Apr 06, 2019 1:46 am
Forum: Beginners
Topic: Simple code to turn on/off relays from buttons on website
Replies: 2
Views: 97

Re: Simple code to turn on/off relays from buttons on website

Look this over.
In the example they are only controlling a LED from a web page, but if that can be controlled, so can anything else (like a relay) with the proper interfacing.

https://www.w3schools.com/nodejs/nodejs ... socket.asp
by JohnsUPS
Sun Mar 31, 2019 11:37 pm
Forum: Beginners
Topic: Input Relay Board
Replies: 22
Views: 424

Re: Input Relay Board

To test this board, don't put a LED across OUT1 (or 2 or 3) to ground. What you were measuring (if I read your post right) was the voltage drop across the LED. The LED was bright probably because there is no series resistance between it and the output of the board, and the output appears to be switc...
by JohnsUPS
Sat Mar 30, 2019 8:10 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: DS18B20 Max Distance
Replies: 41
Views: 41239

Re: DS18B20 Max Distance

You may be able to get away with a star topology if the sensors are on legs of different lengths, but I would not expect the system to be too stable if you can get it to work. Suspect that if it did work, it would still suffer from occasional bad reads. The distance between sensors that I quoted was...
by JohnsUPS
Fri Mar 29, 2019 3:14 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: DS18B20 Max Distance
Replies: 41
Views: 41239

Re: DS18B20 Max Distance

Frank When you state I have tried to get sensors recognized that are the same distance from the master , it sounds like you have created a "star" topology, which is something that does not play nicely with the 1-wire protocol. Instead of wiring the sensors back to the same point, connect each subseq...
by JohnsUPS
Tue Mar 26, 2019 12:40 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: DS18B20 Max Distance
Replies: 41
Views: 41239

Re: DS18B20 Max Distance

@JohnsUPS, Thank you for all your hard work on this and for providing the ideas you have to make it work. I've been battling this myself. Today, I doubled up on conductors per your advice. And it seems things may be working better. I am not using a driver chip, nor am I using a RPi. (yet). I ended ...
by JohnsUPS
Thu Mar 21, 2019 12:06 am
Forum: Advanced users
Topic: Multiple DS18B20 temperature sensors
Replies: 25
Views: 13456

Re: Multiple DS18B20 temperature sensors

I am not that much of a fan of using a GPIO pin as the data pin when talking to DS18B20 sensors. For better performance I'd advocate using a driver chip powered from 5 volts. For your application, I'd recommend using the eight channel driver chip. This way you don't have to string one long wire arou...
by JohnsUPS
Sat Mar 16, 2019 3:59 pm
Forum: General discussion
Topic: Can Pi be powered by stepped sine wave power generated by a UPS?
Replies: 26
Views: 1064

Re: Can Pi be powered by stepped sine wave power generated by a UPS?

120VAC RMS * 1.414.= 169.68 peak. I stand corrected - I meant peak, not P-P. Otherwise, what I stated about discussions concerning voltage and wattage values being in RMS terms versus peak values still holds true. You still have not addressed my question about your "Cos .707 = 0.999". It just is. It...
by JohnsUPS
Thu Mar 14, 2019 9:57 pm
Forum: General discussion
Topic: Can Pi be powered by stepped sine wave power generated by a UPS?
Replies: 26
Views: 1064

Re: Can Pi be powered by stepped sine wave power generated by a UPS?

The 1/2SQRT of 2 (.707) was from an earlier post. I believe that the formula presented was probably to allow for a margin (.7PF) when sizing a UPS. Otherwise, at unity power factor, W=VA. AC power is generally quoted as peak-to-peak value. The 1/2 * SQRT(2) (0.707, rounded to 0.7) is to get the roo...
by JohnsUPS
Tue Mar 12, 2019 12:25 pm
Forum: General discussion
Topic: Can Pi be powered by stepped sine wave power generated by a UPS?
Replies: 26
Views: 1064

Re: Can Pi be powered by stepped sine wave power generated by a UPS?

JohnsUPS wrote: ↑ Mon Mar 11, 2019 5:52 pm I have always known AC wattage to be: V * I * cosine of the voltage/current phase angle (theta). Cos .707 = .999. @JohnsUPS Where has that .707 come from? The "half of root 2" in an earlier post is not an angle. Also you are wrong when you say "As for a sw...
by JohnsUPS
Mon Mar 11, 2019 10:52 pm
Forum: General discussion
Topic: Can Pi be powered by stepped sine wave power generated by a UPS?
Replies: 26
Views: 1064

Re: Can Pi be powered by stepped sine wave power generated by a UPS?

So long as the power supply connected to the Pi puts out a clean 5v DC when power by a UPS running on its batteries, you'll be OK. Due to the nature of how a switching power supply works, I believe that the vast majority of the supplies out there will work just fine. Unless the UPS is a seriously in...
by JohnsUPS
Sun Mar 10, 2019 9:13 pm
Forum: Beginners
Topic: Choosing a device for analog
Replies: 7
Views: 259

Re: Choosing a device for analog

Here are a couple of additional suggestions for obtaining pulses: Affix a magnet or two to the rotating part (wheel and front sprocket), and locate hall effect sensors so that they switch when the magnet travels by it. Count the pulses of each, and do the math in software. Affix an optical pickup so...
by JohnsUPS
Sun Mar 10, 2019 8:54 pm
Forum: General discussion
Topic: Pi 3 gets too hot
Replies: 33
Views: 776

Re: Pi 3 gets too hot

If the Pi is abnormally heating up without an SD card installed, you should consider it toast and replace it. The problem is most likely down deep within an IC on the board (most likely the uproc). Finishing your project but having the Pi live in the refrigerator is a poor solution. Attempting to re...

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