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by davidcoton
Sun Jun 24, 2018 6:32 pm
Forum: Beginners
Topic: 5V relay to control a 0.5HP pump
Replies: 19
Views: 244

Re: 5V relay to control a 0.5HP pump

The relay you have found will work, it appears to be correctly rated I'm not convinced of that at all. I can't see any specification for inductive loads, only the vague claim that it can be used to switch motors - how big a motor? That's why I said "possibly". The picture of the relay shows two cur...
by davidcoton
Sun Jun 24, 2018 6:26 pm
Forum: Python
Topic: Simplifying 'if' statements
Replies: 3
Views: 98

Re: Simplifying 'if' statements

I would try to make a generic routine that works for any airport, and run it in a loop based on a dictionary or airports of interest. Basically define a dictionary that associates each airport (identified by its code) with the index required to fetch the data, and the LED index. See dictionaries in ...
by davidcoton
Sun Jun 24, 2018 5:48 pm
Forum: Troubleshooting
Topic: Why Raspberry Pi is affected by USB KIller?
Replies: 5
Views: 129

Re: Why Raspberry Pi is affected by USB KIller?

Protection on the LAN9514 is for ESD (electrostatic discharge), which is high voltage but very low current, if one excludes direct lightening strikes. The USB Killer can provide sufficient current to overwhelm static protection, even though it is (comparatively) low voltage. NB 215VDC is still enoug...
by davidcoton
Sun Jun 24, 2018 5:25 pm
Forum: Beginners
Topic: First DIY project for security prevention
Replies: 4
Views: 129

Re: First DIY project for security prevention

I would avoid camera activation based on camera itself Why? My first suggestion woyuld be to try a Pi0W and Pi camera running OpenCV to detect motion, and then emailing a snapshot. Assuming you already have a wireless network, that requires just one PSU for the Pi and camera, and no :o signal cable...
by davidcoton
Sun Jun 24, 2018 5:15 pm
Forum: Beginners
Topic: 5V relay to control a 0.5HP pump
Replies: 19
Views: 244

Re: 5V relay to control a 0.5HP pump

The relay you have found will work, it appears to be correctly rated and it will cut the live supply which is all that is necessary functionally as long as your main isolator is a 2-pole RCD. It will need careful wiring and a plastic (or earthed metal) fully enclosed box to be safe for mains. Howeve...
by davidcoton
Sun Jun 24, 2018 11:35 am
Forum: Beginners
Topic: 5V relay to control a 0.5HP pump
Replies: 19
Views: 244

Re: 5V relay to control a 0.5HP pump

What about contactors? can I keep starter button on and power start unit from contactor and then control contactors from relay?. As has been said, you need two relays to control the pump. One driving a contactor to turn the power on, and later off to stop the pump. The other to operate the starter....
by davidcoton
Sun Jun 24, 2018 11:23 am
Forum: Beginners
Topic: 5V relay to control a 0.5HP pump
Replies: 19
Views: 244

Re: 5V relay to control a 0.5HP pump

Thanks DougieLawson and Z80 Refugee for your response. @Z80 Refugee can you please help me to understand ur putting relay in starter unit solution? i am thinking to keep start button always on and controlling starter unit from relay board. will it work? It might work. It might also burn out the mot...
by davidcoton
Sun Jun 24, 2018 11:10 am
Forum: Troubleshooting
Topic: Raspberry Pi 3B+ WiFi issues CONN_FAILED
Replies: 5
Views: 110

Re: Raspberry Pi 3B+ WiFi issues CONN_FAILED

glynhudson wrote:You can mark this topic as resolved.
Actually, you can do that. Go back to your first post in the thread, edit the title to include the tag "[Solved]". Job done :D
by davidcoton
Sun Jun 24, 2018 11:02 am
Forum: Beginners
Topic: 5V relay to control a 0.5HP pump
Replies: 19
Views: 244

Re: 5V relay to control a 0.5HP pump

I don't recommend motorising the breaker switch - just use a contactor to control the whole supply. The breaker may also be a current protection device, and you wouldn't want some remote control mechanism stopping it tripping out. A servo (or solenoid) could press the button to start up (the length...
by davidcoton
Sat Jun 23, 2018 3:19 pm
Forum: Beginners
Topic: Using Pass-through for GPIO on pi zero / B+
Replies: 6
Views: 896

Re: Using Pass-through for GPIO on pi zero / B+

used with extra tall header pins, you could put 2 or 3 hats on a pi... If the boards conform to the HAT specification, they have an EEPROM on board that means they cannot be stacked. Many Pi expansion boards are not actually HATS, in which case they can be stacked as long as they don't compete for ...
by davidcoton
Sat Jun 23, 2018 3:03 pm
Forum: General discussion
Topic: Raspberry Pi 3 B+ POE - Powering other devices 8 - 12 V DC & 150 mA
Replies: 13
Views: 364

Re: Raspberry Pi 3 B+ POE - Powering other devices 8 - 12 V DC & 150 mA

If the POE-HAT has a polyfuse? That's an assumption ;-) it probably does though. , so what is your suggestion, just look at it and not bother ? Actually my assumption (probably incorrect, on reflection) was that the POE power went via the Pi polyfuse. If it doesn't, and the HAT doesn't have a polyf...
by davidcoton
Sat Jun 23, 2018 9:41 am
Forum: General discussion
Topic: Raspberry Pi 3 B+ POE - Powering other devices 8 - 12 V DC & 150 mA
Replies: 13
Views: 364

Re: Raspberry Pi 3 B+ POE - Powering other devices 8 - 12 V DC & 150 mA

Try and see, worst is it doesn't work, not particularly dangerous. Worst is blown polyfuse and corrupted SDCard (possibly permanenmtly locked read-only). Not an area to experiment unless you can face that. As for the voltage to the RTL-SDR, we don't know if: It uses the voltage directly, in which c...
by davidcoton
Fri Jun 22, 2018 4:36 pm
Forum: General discussion
Topic: Raspberry Pi 3 B+ POE - Powering other devices 8 - 12 V DC & 150 mA
Replies: 13
Views: 364

Re: Raspberry Pi 3 B+ POE - Powering other devices 8 - 12 V DC & 150 mA

I'm assuming the PoE is 2500mA capable, it's for a 3B+ after all. Need here 150mA plus conversion loss. Which is probably less than adding a Pi camera? Certainly some LED HATs Asumptions are dangerous, even when reasonable. 150mA at 12V is 1.8W, or 360mA at 5V. Still possible, but what else is also...
by davidcoton
Fri Jun 22, 2018 4:17 pm
Forum: General discussion
Topic: Pi Is Too Complicated
Replies: 66
Views: 1887

Re: Pi Is Too Complicated

My opinion is that it comes back to education. The (perceived) needs of educators should not be the major driving force, even for a product aimed at "education". Education itself must learn how to teach students to be functional in a fast moving technological world. As my Dad once said, the purpose ...
by davidcoton
Fri Jun 22, 2018 3:45 pm
Forum: General discussion
Topic: Raspberry Pi 3 B+ POE - Powering other devices 8 - 12 V DC & 150 mA
Replies: 13
Views: 364

Re: Raspberry Pi 3 B+ POE - Powering other devices 8 - 12 V DC & 150 mA

up volt from the 5V gpio line with a buck convertor? or USB ports if that provides greater protection than gpio pins 2 or 4. (just throwing the idea out there, I've not done it) Good idea, I was looking at this today. Just watch the total load at 5V is still within the capacity of the POE -- I don'...
by davidcoton
Thu Jun 21, 2018 10:46 pm
Forum: Troubleshooting
Topic: General Power issue (yellow bolt) with Pi 3 B+?
Replies: 13
Views: 627

Re: General Power issue (yellow bolt) with Pi 3 B+?

Hi, I am having the same issue. My Raspberry Pi 3Bs (two of them) have worked fine with various cables and chargers used. Those same ones are not working. The SD cards i was using on those 3Bs were full updated and upgraded before the switch. Any chance this is related to where they are purchased? ...
by davidcoton
Thu Jun 21, 2018 5:35 pm
Forum: General discussion
Topic: Pi Is Too Complicated
Replies: 66
Views: 1887

Re: Pi Is Too Complicated

… there are limits to how far you can uncomplex* it. * New word, ™ jamesh. “simplify” would've been shorter, as Heater noted … and we have so many Linux distributions purely because we can. How about uncomplexify? Simplificate? And if natural language can be so illogical, isn't it inevitable that O...
by davidcoton
Thu Jun 21, 2018 8:46 am
Forum: General discussion
Topic: STICKY: PMs being turned off from June 13
Replies: 54
Views: 2652

Re: STICKY: PMs being turned off from June 13

Imperf3kt wrote:
Wed Jun 20, 2018 11:21 pm
Not what I am looking for. Please don't insult my intelligence, I'm not so dumb that I cannot read the first post.
But it was what you asked for:
Imperf3kt wrote: Is it possible to point out the particular law or reason they were locked off for in the first place?
I won't try to help you again.
by davidcoton
Wed Jun 20, 2018 11:07 pm
Forum: General discussion
Topic: STICKY: PMs being turned off from June 13
Replies: 54
Views: 2652

Re: STICKY: PMs being turned off from June 13

Is it possible to point out the particular law or reason they were locked off for in the first place? Read the first post of the thread. Thats as useful as telling someone looking for a specific tree species, to look in a forest. Oh come on -- if you really need spoon feeding, here : An important p...
by davidcoton
Wed Jun 20, 2018 11:04 pm
Forum: Troubleshooting
Topic: Raspbian OS unreachable after several hours of use
Replies: 29
Views: 746

Re: Raspbian OS unreachable after several hours of use

The red LED turning off at any time on a Pi3B means you have a power problem. There is one important exception, though not relevant here. If an older, insufficiently upgraded OS is used on a Pi3B+, because of internal circuit changes the "ouit of date" signal appears of the RED LED, not the green o...
by davidcoton
Wed Jun 20, 2018 10:55 pm
Forum: General discussion
Topic: STICKY: PMs being turned off from June 13
Replies: 54
Views: 2652

Re: STICKY: PMs being turned off from June 13

Imperf3kt wrote:
Wed Jun 20, 2018 10:49 pm
Is it possible to point out the particular law or reason they were locked off for in the first place?
Read the first post of the thread.
by davidcoton
Mon Jun 18, 2018 8:13 pm
Forum: Troubleshooting
Topic: [Resolved] Electrical noise if ethernet is connected.
Replies: 9
Views: 227

Re: Electrical noise if ethernet is connected.

The Traveler wrote:
Mon Jun 18, 2018 8:07 pm
That one shouldn't matter. The Pi Ethernet port is autosensing.
Yes, but I usually mention it just to eliminate it early as it does occasionally happen.

Cheers.
It doesn't matter. A crossover cable will still work, in the absence of other problems. That's what autosensing does.
by davidcoton
Mon Jun 18, 2018 7:47 pm
Forum: Troubleshooting
Topic: [Resolved] Electrical noise if ethernet is connected.
Replies: 9
Views: 227

Re: Electrical noise if ethernet is connected.

The Traveler wrote:
Mon Jun 18, 2018 3:38 pm
Be sure you're not using a cross-over cable as well. It's easy to mistake them without being clearly marked or examining the RJ-45 ends. It happens.
That one shouldn't matter. The Pi Ethernet port is autosensing.
by davidcoton
Sat Jun 16, 2018 9:09 pm
Forum: General discussion
Topic: Generating smoke from a Pi Zero
Replies: 15
Views: 460

Re: Generating smoke from a Pi Zero

But there are no data connections to the Power socket. My guess is that a short from either stray metal on the board or a component failure led to enough current (the Pi0W having no polyfuse) to damage the cable -- most likely at a connection to the plug. However it is unusual (in my experience) to ...
by davidcoton
Fri Jun 15, 2018 10:42 pm
Forum: Troubleshooting
Topic: raspberry pi 3 b+ Rainbow screen
Replies: 4
Views: 171

Re: raspberry pi 3 b+ Rainbow screen

Okay, that narrows things down a bit. I can think of three possibilities: Fault in writing to the SDCard. What hardware did you use to write the SDCard? Is it SDHC compatible? SDCard itself is faulty. Have you checked it? Do you know anyone else with a Pi who could check it for you? Pi is faulty (Un...

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