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by NGC6543
Sun Apr 07, 2019 5:28 pm
Forum: Raspbian
Topic: getting gps to work on raspberry pi 3
Replies: 23
Views: 1640

Re: getting gps to work on raspberry pi 3

I'm on Stretch (with recommended software). I'm new to the RPi and Linux in general, so if anyone else wants to step in they can probably help more. However, the second thing I did with mine, last week, was set up a GPS module and configure the Pi to use the PPS output for the time source for ntp. I...
by NGC6543
Sat Apr 06, 2019 9:37 pm
Forum: Raspbian
Topic: getting gps to work on raspberry pi 3
Replies: 23
Views: 1640

Re: getting gps to work on raspberry pi 3

Did you follow any guide on setting it up? Have you disabled the console access on the serial port? Have you installed gpsd? Most of the instructions on the 'net work for most GPS modules. You should be able to cat the NMEA strings without installing anything, as a first test, once you've disabled s...
by NGC6543
Fri Apr 05, 2019 10:13 pm
Forum: Automation, sensing and robotics
Topic: How best to control higher voltage relays with 12v/24v coils?
Replies: 26
Views: 1655

Re: How best to control higher voltage relays with 12v/24v coils?

Just to add: you could make do with much cheaper MOSFETs than the one I put in the diagram. That was just an example really to get us going, given that I didn't know much of your requirements (and I'm not up on MOSFET part numbers any more but was using that exact part myself that day). You just nee...
by NGC6543
Fri Apr 05, 2019 9:09 pm
Forum: Automation, sensing and robotics
Topic: How best to control higher voltage relays with 12v/24v coils?
Replies: 26
Views: 1655

Re: How best to control higher voltage relays with 12v/24v coils?

I would not do this without optocouplers to the Pi and I don't see why they are 'best avoided'. They are there to protect the Pi from the 12V switching a lot of relays circuit. The relay isolation protects the switching board (and everything else) from the mains side. Still, I worked in high availab...
by NGC6543
Fri Apr 05, 2019 3:59 pm
Forum: Troubleshooting
Topic: I suspect My Pi is bricked, due to a failed PSU, but how do I check?
Replies: 25
Views: 980

Re: I suspect My Pi is bricked, due to a failed PSU, but how do I check?

:oops: Thanks guys, I got confused between polyfuse and TVS. :oops: I blame morning caffeine deficiency. :D I had to call the doctors as soon as I got up this morning. The receptionist asked my date of birth... it took me a good fifteen seconds to remember it! And then I wondered momentarily if I w...
by NGC6543
Fri Apr 05, 2019 11:10 am
Forum: Troubleshooting
Topic: Can I get back the flashing green light?
Replies: 8
Views: 295

Re: Can I get back the flashing green light?

All that did was stop the poweroff from completing. Thanks anyway. What makes you think it didn't complete? (ETA: You did disable your script when you tried the other method, didn't you?) The Pi doesn't power off as such - it just halts*. Either method produces exactly the same result as far as I c...
by NGC6543
Fri Apr 05, 2019 11:00 am
Forum: Troubleshooting
Topic: I suspect My Pi is bricked, due to a failed PSU, but how do I check?
Replies: 25
Views: 980

Re: I suspect My Pi is bricked, due to a failed PSU, but how do I check?

davidcoton wrote:
Fri Apr 05, 2019 9:49 am
The polyfuse is on the top side of every Pi I have checked (B+ 2B 3B 3A+) except the original B. Not fitted on Pi0 of course.
Note that the component number varies between models.
This is it underneath on the 3B+
polyfuse2.jpg
polyfuse2.jpg (124.27 KiB) Viewed 598 times
by NGC6543
Thu Apr 04, 2019 1:58 pm
Forum: Troubleshooting
Topic: Can I get back the flashing green light?
Replies: 8
Views: 295

Re: Can I get back the flashing green light?

Can't help with the light, but you don't need a script for that on the 3B+. Just add the following line to /boot/config.txt dtoverlay=gpio-shutdown,gpio_pin=3 You can change the GPIO pin, but leaving it at 3 means the same button will start the Pi up again too. Of course, if you use I2C which uses t...
by NGC6543
Wed Apr 03, 2019 9:35 pm
Forum: Troubleshooting
Topic: I suspect My Pi is bricked, due to a failed PSU, but how do I check?
Replies: 25
Views: 980

Re: I suspect My Pi is bricked, due to a failed PSU, but how do I check?

Imperf3kt wrote:
Wed Apr 03, 2019 8:40 pm
This is one of the reasons I prefer to step up the voltage
You know, I never thought of that! Not that it's an option for what I'm doing right now, but next time...
by NGC6543
Wed Apr 03, 2019 7:38 pm
Forum: Automation, sensing and robotics
Topic: Know where I can get reasonably priced DPST/DPDT 240v/8a to 240v/10a relays?
Replies: 16
Views: 1185

Re: Know where I can get reasonably priced DPST/DPDT 240v/8a to 240v/10a relays?

Those little relays are nice, but (1) are only single pole (we really need two) and (2) will not cope with the inrush current of the big SMPSs it's going to be switching. They can have an inrush measured in tens of amps. A Dell server I know with a similar power requirement is specified to have not ...
by NGC6543
Wed Apr 03, 2019 7:21 pm
Forum: Troubleshooting
Topic: I suspect My Pi is bricked, due to a failed PSU, but how do I check?
Replies: 25
Views: 980

Re: I suspect My Pi is bricked, due to a failed PSU, but how do I check?

For a through hole, SA5.0A is pretty close or maybe a 1N6373.

I'm going to be buying some myself for my PSU soon, along with some fuses :D
by NGC6543
Wed Apr 03, 2019 4:34 pm
Forum: Automation, sensing and robotics
Topic: Know where I can get reasonably priced DPST/DPDT 240v/8a to 240v/10a relays?
Replies: 16
Views: 1185

Re: Know where I can get reasonably priced DPST/DPDT 240v/8a to 240v/10a relays?

Do you know the inrush current of the SMPS you are switching? It should be on the specifications from the manufacturer. Anyway, one thing to consider is how you are going to mount the relays. Are you making a PCB that you can cut slots in for relay tags and mains side isolation distance? Most relays...
by NGC6543
Tue Apr 02, 2019 7:29 pm
Forum: Networking and servers
Topic: Raspberry Pi Router not Resolving DNS
Replies: 5
Views: 584

Re: Raspberry Pi Router not Resolving DNS

You probably know this, but just to make sure: 127.0.2.1 is what DNSCrypt is listening on. BIND is configured to use 127.0.2.1 as its upstream server, but BIND itself listens on 127.0.0.1. So, 127.0.0.1 is what you want to set as the Pi's nameserver. Why it would change back after you edited /etc/dh...
by NGC6543
Tue Apr 02, 2019 3:41 pm
Forum: Beginners
Topic: rasberry pi controlling 50 relays
Replies: 8
Views: 389

Re: rasberry pi controlling 50 relays

Yes, there are a few ways to tackle this. A bank of 74HC595 can be daisy chained. A possibly useful aspect of those is the Output Enable, to keep the outputs high impedance while the data is clocked in and then all fired together by setting the OE pin. I would throw a MAX EPM7128AE CPLD (or similar)...
by NGC6543
Tue Apr 02, 2019 10:54 am
Forum: Graphics, sound and multimedia
Topic: Blender
Replies: 8
Views: 751

Re: Blender

You have Blender installed on a Pi???

I think it runs slowly sometimes on my 3.4Ghz i7 laptop with 32GB RAM... and go onto my main system to work on it instead.

Try adding Avastar as well... you'll melt the poor thing.
by NGC6543
Tue Apr 02, 2019 3:18 am
Forum: Advanced users
Topic: To much of a good thing? Using a AMS1117-3.3 regulator?
Replies: 2
Views: 338

Re: To much of a good thing? Using a AMS1117-3.3 regulator?

I'm not sure exactly what you are doing but... The tachometer output on fans is usually an open collector or open drain, but might have an internal pull-up to the fan supply voltage. The transistor pulls the tach output to ground to give 1, 2 or 4 pulses per revolution (depends on the fan). The outp...
by NGC6543
Tue Apr 02, 2019 2:27 am
Forum: Networking and servers
Topic: Raspberry Pi Router not Resolving DNS
Replies: 5
Views: 584

Re: Raspberry Pi Router not Resolving DNS

Your Pi/router should be able to resolve locally. What happens if you enter (on the router): dig @127.0.0.1 google.com If it works, BIND is listening locally and probably all you need to do is tell the rest of the Pi what its DNS resolver is... 127.0.0.1. In Raspbian that's done in /etc/dhcpcd.conf ...
by NGC6543
Sun Mar 31, 2019 5:12 pm
Forum: Automation, sensing and robotics
Topic: How best to control higher voltage relays with 12v/24v coils?
Replies: 26
Views: 1655

Re: How best to control higher voltage relays with 12v/24v coils?

...then add another relay to supply the other load then the contact ratings aren't exceeded per contact. That makes sense now. No more nightmares about welded contacts on one leg of the supply causing havoc :lol: I agree on using known quality relays from a reputable supplier, especially for an SMP...
by NGC6543
Sun Mar 31, 2019 1:33 pm
Forum: Automation, sensing and robotics
Topic: How best to control higher voltage relays with 12v/24v coils?
Replies: 26
Views: 1655

Re: How best to control higher voltage relays with 12v/24v coils?

you can use those relays direct (240V/10A contact rating) or parallel them up (10A x n) Do you mean to connect multiple relay's contacts in parallel to increase the current handling? Don't do that! There will always be one contact that closes a bit quicker than the others and takes the hit... it wi...
by NGC6543
Sun Mar 31, 2019 1:26 pm
Forum: Automation, sensing and robotics
Topic: How best to control higher voltage relays with 12v/24v coils?
Replies: 26
Views: 1655

Re: How best to control higher voltage relays with 12v/24v coils?

Hey NGC6543, would it be possible to use these Darlington arrays? Yes, but you have no optical isolation with those. Plus they'll drop about 1.4V from your relay supply but that shouldn't stop your relays working. I would feel uncomfortable with not having the isolation myself. Things do occasional...
by NGC6543
Sat Mar 30, 2019 7:43 pm
Forum: Automation, sensing and robotics
Topic: How best to control higher voltage relays with 12v/24v coils?
Replies: 26
Views: 1655

Re: How best to control higher voltage relays with 12v/24v coils?

First... the problem with using big SSRs to switch the PSUs directly is that the SSRs leak current when off and connected to an AC supply. This is because they contain a snubber circuit on the output. This leakage will slowly charge the capacitors in the PSU and cause it to cycle on every time the c...
by NGC6543
Fri Mar 29, 2019 9:49 pm
Forum: Automation, sensing and robotics
Topic: How best to control higher voltage relays with 12v/24v coils?
Replies: 26
Views: 1655

Re: How best to control higher voltage relays with 12v/24v coils?

There certainly are better ways if you're open to some soldering. I would use an opto coupler to drive a MOSFET, to drive the relay. Alternatively you could use a MOSFET photorelay which is an optocoupler with a MOSFET 'output' in one little package. For instance the TLP172A will happily run off a G...
by NGC6543
Fri Mar 29, 2019 3:57 pm
Forum: Automation, sensing and robotics
Topic: Wiring relay to Pi
Replies: 27
Views: 1567

Re: Wiring relay to Pi

I agree with PhatFil. Pulling the LEDs might well solve the issue by lowering the current required; depends if they used low current (2mA) LEDs or not. The relay is driven through the transistor that can be seen on the board. My guess is the transistor is connected common collector, rather than in t...
by NGC6543
Thu Mar 28, 2019 9:32 am
Forum: General discussion
Topic: What Power supply to power Raspberry + 10inch screen + LED Light
Replies: 3
Views: 148

Re: What Power supply to power Raspberry + 10inch screen + LED Light

The specs for that panel and driver are a bit vague; I bet it doesn't actually need 12V*2A=24W. Likewise, your LED light... 5V*1A=5W is a very bright LED. It's enough to fully light a small room. Still, we'll work with those values: For the 5V parts, you need 2A for the Raspberry plus 1A for the LED...
by NGC6543
Tue Mar 26, 2019 8:53 pm
Forum: Beginners
Topic: Using RPi to spoof ISP gateway
Replies: 4
Views: 184

Re: Using RPi to spoof ISP gateway

I'll swallow my jealousy of your gigabit internet... I've not head of an ISP doing that. At first thought, it sounds to me like you need a basic router (or router OS on an SBC) that does overloaded NAT (usually just called NAT on consumer routers; they all do it). But it might be more complicated, d...

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