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by davidcoton
Thu Sep 19, 2019 9:31 pm
Forum: Beginners
Topic: Leak sensor too sensitive
Replies: 11
Views: 187

Re: Leak sensor too sensitive

I am not sure where you are thinking to put the 1M resistor. The water acts as about a 0.7M resistor across the sensor. Are you saying I need a resistor in series with the capacitor? The 1M goes from base to emitter of the 2n2222, directly in parallel with the capacitor.. It will not affect the tri...
by davidcoton
Thu Sep 19, 2019 4:49 pm
Forum: Beginners
Topic: Leak sensor too sensitive
Replies: 11
Views: 187

Re: Leak sensor too sensitive

The sensor is just 2 metal probes stuck in a piece of plastic about 1.5" apart. The sensor is then connected to the base of a 2N222 transistor. It definitely made the sensor more sensitive to small amounts of water. I did figure it out that the capacitor needs to be on the sensor/base not the emitt...
by davidcoton
Thu Sep 19, 2019 4:46 pm
Forum: General discussion
Topic: Small piwiz race condition (time sync)
Replies: 25
Views: 603

Re: Small piwiz race condition (time sync)

knute wrote:
Thu Sep 19, 2019 4:42 pm
Thanks very much for digging into that, that is really interesting.
+1 or more.
by davidcoton
Thu Sep 19, 2019 4:42 pm
Forum: General discussion
Topic: Low voltage warning even though gpio being powered with 5.07V?
Replies: 27
Views: 820

Re: Low voltage warning even though gpio being powered with 5.07V?

Power was fed to the Pis via short USB cables that had the input ends chopped off... While i am perfectly understanding why the RPF has chosen micro-USB connectors to feed the Pis, (they are practically fool-proof since they are always 5V) I prefer using 5.5x2.1mm male in-line plug jack sockets wir...
by davidcoton
Thu Sep 19, 2019 3:13 pm
Forum: Advanced users
Topic: Where can I hire a Raspberry Pi expert to solve random hang problems
Replies: 11
Views: 487

Re: Where can I hire a Raspberry Pi expert to solve random hang problems

If none can help me to solve the problem through the forum, could anyone tell me where I can find an expert in Raspberry Pi I can hire to help me to solve the problem by direct remote debugging? There's a Forum section "Wanted" that has been used to recruit consultants. A handful of regulars (to th...
by davidcoton
Thu Sep 19, 2019 2:33 pm
Forum: Beginners
Topic: Leak sensor too sensitive
Replies: 11
Views: 187

Re: Leak sensor too sensitive

What are you using as a sensor? I had assumed two bare wires driving a Darlington or FET amplifier, the output of which drives the GPIO. The pull-down/capacitor needs to be on the amplifier input, not the GPIO.
by davidcoton
Wed Sep 18, 2019 8:58 pm
Forum: General discussion
Topic: Small piwiz race condition (time sync)
Replies: 25
Views: 603

Re: Small piwiz race condition (time sync)

RonR wrote:
Wed Sep 18, 2019 8:47 pm
Regardless of the reason/explanation, it's not right.
True, but understanding why it goes wrong may help put it right.
by davidcoton
Wed Sep 18, 2019 8:41 pm
Forum: General discussion
Topic: Small piwiz race condition (time sync)
Replies: 25
Views: 603

Re: Small piwiz race condition (time sync)

Should we be concerned with? I wouldn't be, but I never tried to find out why systemd says it. It could make sense if you modified a service and restarted it without running that command, but in this case, contrary to the message, no changes have been made. No changes of any sort anywhere have been...
by davidcoton
Wed Sep 18, 2019 4:10 pm
Forum: Troubleshooting
Topic: USB Blown is there any USB output on GP10.
Replies: 14
Views: 278

Re: USB Blown is there any USB output on GP10.

The chip was pretty charred so I poked it a bit and it fell apart, I checked none of its remaining leads were shorting then as on on youtube connected pin 1 on GP10 to pp27 and it worked again and USBs too. If the chip is current limit will that effect me at all? Back in business I hope. If you rea...
by davidcoton
Wed Sep 18, 2019 3:52 pm
Forum: General discussion
Topic: stuck in wifi - Debian wheezy
Replies: 11
Views: 336

Re: stuck in wifi - Debian wheezy

jamesh wrote:
Wed Sep 18, 2019 3:48 pm
Dougie is right, Wheezy is very old, we are currently two three entire OS releases newer. Try a new SD card with a fresh install of Buster, if that still goes wrong, then we can look at it.
FTFY. (Wheezy, Jessie, Stretch, Buster). :ugeek:
by davidcoton
Wed Sep 18, 2019 3:43 pm
Forum: General discussion
Topic: Power over Ethernet and Fan
Replies: 9
Views: 179

Re: Power over Ethernet headed

I suppose someone could design a HAT or other add-on board that would take power from those pins and convert it to something a fan could run on, but it would still only work if the Pi was connected to a PoE switch. "Someone" already has. "Someone" is RPT, and it's called the Raspberry Pi PoE HAT. :...
by davidcoton
Wed Sep 18, 2019 3:26 pm
Forum: Beginners
Topic: Leak sensor too sensitive
Replies: 11
Views: 187

Re: Leak sensor too sensitive

So is the capacitor essentially a low pass filter mopping up the stray noise before it gets to the transistor? Once there is a true signal does the capacitor then fully charge and then allow current to flow to the transistor? I have had a hard time finding 0μ1 capacitors. Is this another way to des...
by davidcoton
Wed Sep 18, 2019 9:17 am
Forum: General discussion
Topic: Raspberry Pi and Fotek SSR-25
Replies: 4
Views: 109

Re: Raspberry Pi and Fotek SSR-25

If your part in genuine it should work, but the trigger current is a little high (7.5mA) if you are drawing current from other GPIOs at the same time. A transistor to switch 5V to the trigger should solve it. Specification Edit: the default GPIO drive strength only guarantees V IH > 1.6V at 8mA, whi...
by davidcoton
Wed Sep 18, 2019 12:18 am
Forum: Beginners
Topic: Leak sensor too sensitive
Replies: 11
Views: 187

Re: Leak sensor too sensitive

Small capacitor (try 0μ1) base to emitter?
by davidcoton
Tue Sep 17, 2019 1:54 pm
Forum: General discussion
Topic: Low voltage warning even though gpio being powered with 5.07V?
Replies: 27
Views: 820

Re: Low voltage warning even though gpio being powered with 5.07V?

Botspot wrote:
Tue Sep 17, 2019 1:43 pm
What wire thickness is necessary?
At least 24AWG. Preferably 18AWG.
by davidcoton
Tue Sep 17, 2019 9:21 am
Forum: General discussion
Topic: RP4 USB Battery Power - E Marked Issue
Replies: 9
Views: 369

Re: RP4 USB Battery Power - E Marked Issue

Why do you advise against the Power Delivery spec? It is, after all, specifically for use as a power supply, up to [email protected]. That's literally what the spec is for. See this Wikipedia article. The power limit at 5V is 15W (3A -- yes even the official Pi PSU does that). Higher power requires higher vo...
by davidcoton
Mon Sep 16, 2019 8:41 am
Forum: General discussion
Topic: Laptop speakers with Raspberry PI
Replies: 25
Views: 561

Re: Laptop speakers with Raspberry PI

W. H. Heydt wrote:
Mon Sep 16, 2019 1:05 am
That is the sort of information that should have been provided at the beginning. How were we to know you had such severe space constraints?
OP's third post:
qaz wrote: The thing is that I need really thin speakers, so dunno. These are the things I thought of...
by davidcoton
Sun Sep 15, 2019 10:58 pm
Forum: Beginners
Topic: Pi 3 Model B GPIO Questions
Replies: 6
Views: 130

Re: Pi 3 Model B GPIO Questions

Careful. You are showing the first signs of PAD (Pi Addiction Disorder). It will take over your life completely if you let it.

With only one Pi, it's not an advanced case. Yet. :twisted:
by davidcoton
Sun Sep 15, 2019 10:55 pm
Forum: Beginners
Topic: Soldering
Replies: 22
Views: 474

Re: Soldering

AIUI that's how boards with a separate pad for each hole should be used -- either use the ends of the component/wire or a separate piece of hookup wire.
by davidcoton
Sun Sep 15, 2019 6:40 pm
Forum: Beginners
Topic: Pi 3 Model B GPIO Questions
Replies: 6
Views: 130

Re: Pi 3 Model B GPIO Questions

https://pinout.xyz/#
It's the same on all 40-pin Pis, and the first 26 are the same on later 26-pin models.
Only three pins are different (numbering only) on the earliest Pis.
by davidcoton
Sun Sep 15, 2019 6:30 pm
Forum: General discussion
Topic: Laptop speakers with Raspberry PI
Replies: 25
Views: 561

Re: Laptop speakers with Raspberry PI

qaz wrote:
Sun Sep 15, 2019 4:42 pm
But really, will it make a difference? Technically
The clue is in the name. Loudspeakers. More noise out, more power in required to drive them.
by davidcoton
Sun Sep 15, 2019 4:38 pm
Forum: General discussion
Topic: Laptop speakers with Raspberry PI
Replies: 25
Views: 561

Re: Laptop speakers with Raspberry PI

You don't want to walk around with a pair of speakers clipped over your ears.
by davidcoton
Sun Sep 15, 2019 4:30 pm
Forum: General discussion
Topic: Laptop speakers with Raspberry PI
Replies: 25
Views: 561

Re: Laptop speakers with Raspberry PI

Working backwards: That Amazon amp will only drive headphones, not speakers. HermannSW's suggestion will require more than £12 worth of time to assemble a working amp (and you will need to learn to solder, and to read Chinese :lol: ) The Pimoroni board should "just work"-- but you may still need to ...
by davidcoton
Sat Sep 14, 2019 2:27 pm
Forum: Troubleshooting
Topic: Buster updates started to fail at 22th August
Replies: 10
Views: 435

Re: Buster updates started to fail at 22th August

OK, so what happened to 'apt-get update'? Someone decided it wasn't broke, so... I would expect "update" to update any files/programs that have minor upgrades and changes I would expect "upgrade" to take me from stretch to buster - major upgrades and changes, new features For whatever reason, your ...

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