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by Burngate
Sun Apr 07, 2019 10:50 am
Forum: Off topic discussion
Topic: Learning Electronics
Replies: 56
Views: 2473

Re: Learning Electronics

Static ram holds its values indefinitely, but dynamic ram needs periodic refresh. While it's doing that, the processor is spinning its heels waiting, so you have no idea about timings.
by Burngate
Sun Apr 07, 2019 10:41 am
Forum: Beginners
Topic: Can I please have a detailed explanation as to why it's better than a laptop and what I can do with it?
Replies: 16
Views: 577

Re: Can I please have a detailed explanation as to why it's better than a laptop and what I can do with it?

You're 13. A friend showed you a Pi and you got interested. You tried to tell other friends about it, and how totally exciting it is. And you got a total blank. Been there, done that. Having got interested in astronomy at a similar age, I wanted to spend a night watching the stars go round. My best ...
by Burngate
Sun Apr 07, 2019 9:49 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Soldering the USB port - does not work
Replies: 16
Views: 625

Re: Soldering the USB port - does not work

Whatever I do, it doesn't work. When I solder a cable to one connector it doesn't work but the normal cable connection still works with that connector. I tried the same with another connector, soldered connection doesn't work, but the normal connection doesn't work, too. I believe soldering changes...
by Burngate
Sun Apr 07, 2019 9:12 am
Forum: Off topic discussion
Topic: Learning Electronics
Replies: 56
Views: 2473

Re: Learning Electronics

And just to come back to the present, I still think a basic understanding of electricity (voltage, current, resistance, capacitance, inductance) followed by how semiconductors work (diodes, transistors of both sorts) is advantageous today. As a separate thread, logic gates should be understood; how ...
by Burngate
Sun Apr 07, 2019 9:01 am
Forum: Off topic discussion
Topic: Learning Electronics
Replies: 56
Views: 2473

Re: Learning Electronics

M. G. Scroggie, "Foundations of Wireless" (1936) updated to "Foundations of Wireless and Electronics"
Bought the 8th ed. in 1971 (though I'd borrowed an earlier edition from the library earlier)
And it's available now as a PDF
by Burngate
Sat Apr 06, 2019 6:22 pm
Forum: General discussion
Topic: AV Connector oxidized
Replies: 14
Views: 1104

Re: AV Connector oxidized

For some reason, I thought it was silver rather than cadmium.
by Burngate
Sat Apr 06, 2019 6:00 pm
Forum: Troubleshooting
Topic: Dead RPi 3 B+ after short circuit pin 1 and 2 of GPIO
Replies: 14
Views: 4423

Re: Dead RPi 3 B+ after short circuit pin 1 and 2 of GPIO

yash2607 wrote:
Sat Apr 06, 2019 1:15 pm
hey did you had any luck with you pi? I myself supplied 5v to Rx pin (10) of my pi and now it seems dead to me.
It is dead.

giox069 hasn't logged on here since November, or posted any more information, so assume his is also still dead.
by Burngate
Sat Apr 06, 2019 8:56 am
Forum: Troubleshooting
Topic: Boot problems on older Pi
Replies: 5
Views: 194

Re: Boot problems on older Pi

Just to be sure, your newest purchase really is a 1B+?
The 2B looks very similar to the 1B+ to the untrained eye, but requires somewhat different software in the boot partition.
by Burngate
Fri Apr 05, 2019 5:55 pm
Forum: Beginners
Topic: Under power icon on screen at start up
Replies: 5
Views: 164

Re: Under power icon on screen at start up

ABOX: https://www.aboxtek.com/products/abox-raspberry-pi-3b-16gb 5V 3A On/Off Switch Power Supply with Micro USB Cable and Noise Filter, specially designed for the Raspberry Pi 3 B+. Equipped with 2 premium copper heat sinks with better heat dissipation than aluminum ones and prevent system failure....
by Burngate
Fri Apr 05, 2019 10:59 am
Forum: Off topic discussion
Topic: Learning Electronics
Replies: 56
Views: 2473

Re: Learning Electronics

Learning Electronics ... Regards BoyOh 87yrs Retired Electrical / Electronics Technician Probably not particularly Raspberry Pi oriented? “Jamesh “ you have surprised me very much, ... The job of a moderator could be difficult in situations such as this - when is teaching computing not teaching com...
by Burngate
Fri Apr 05, 2019 9:43 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: software i2c & 5v slaves
Replies: 4
Views: 260

Re: software i2c & 5v slaves

There are a couple of things you might not be aware of. On that E14 page, the statement The rpi SOC gpio lines have clamping diodes to 3V3 and GND to protect the input. is wrong. The diodes are almost an accident of production, aren't very good diodes, and don't protect the inputs. The hardware i2c ...
by Burngate
Thu Apr 04, 2019 5:46 pm
Forum: Off topic discussion
Topic: Learning Electronics
Replies: 56
Views: 2473

Re: Learning Electronics

Back in the day, I used a real breadboard with nails knocked in, until my mother gave me a wallop (she said it ruined the toast)
by Burngate
Thu Apr 04, 2019 8:36 am
Forum: Automation, sensing and robotics
Topic: Garden automation electronics schematic
Replies: 6
Views: 400

Re: Garden automation electronics schematic

To enlarge on ptimlin's post, regarding whether to control the positive or negative side of the valve ... If you want to control the positive leg using an N-channel FET, the GPIO would have to provide a voltage higher than the 12v feeding the valve to switch it on - not impossible but over-complicat...
by Burngate
Wed Apr 03, 2019 6:00 pm
Forum: Troubleshooting
Topic: no power when camera attached
Replies: 11
Views: 191

Re: no power when camera attached

"Raspberry pi 3 B+ DSI conector" viewtopic.php?p=1382804 may be of interest.
It's the other connector, and 3B+ rather than 3B but ...
by Burngate
Wed Apr 03, 2019 5:50 pm
Forum: Troubleshooting
Topic: Tried to repair RPIB+ models that won't boot.
Replies: 2
Views: 96

Re: Tried to repair RPIB+ models that won't boot.

If you've got a red light, 5v is reaching the Pi, so the tvs isn't at fault.

Try "STICKY: Is your Pi not booting? (The Boot Problems Sticky)" viewtopic.php?f=28&t=58151
The red paragraph starting "If you have a PI3B+" is relevant
by Burngate
Wed Apr 03, 2019 8:35 am
Forum: General discussion
Topic: Under-voltage detected! Which is the maximum power voltage for Raspb3?
Replies: 11
Views: 723

Re: Under-voltage detected! Which is the maximum power voltage for Raspb3?

So you're losing 250 mV.
There's a polyfuse, MF-MSMF250/x, between the input and the rest of the 5v including the GPIO header.
It should have between 15 and 100 mΩ resistance, so to drop that much you would have to be taking 2.5A
by Burngate
Tue Apr 02, 2019 9:40 am
Forum: General discussion
Topic: recuperate green led status ?
Replies: 5
Views: 186

Re: recuperate green led status ?

Most of my Pis don't stay in a case long enough to make what you suggest reasonable; perhaps I'm not average. From the schematic vvvvvvv.png You could possibly unsolder the LED and extend it to where you want, or perhaps add some circuit to detect the voltage on PP13. The Pi is yours to do with what...
by Burngate
Mon Apr 01, 2019 5:06 pm
Forum: Beginners
Topic: Input Relay Board
Replies: 22
Views: 498

Re: Input Relay Board

One of the things that initially bemused me was that "3 Channel AC 220V Optocoupler Isolation Board AC Detection Testing Module" being referred to as a relay - it isn't. Without having one in my hands, I can't be sure, but it appears to take in three phases and neutral, rectify them, and pass the re...
by Burngate
Mon Apr 01, 2019 4:52 pm
Forum: Troubleshooting
Topic: 5V on test points but still undervoltage lightning bolt
Replies: 15
Views: 507

Re: 5V on test points but still undervoltage lightning bolt

The output voltage and current stay the same. ... according to P_in = P_out, so U_in * I_in = U_out * I_out That bit is correct (apart from inefficiencies) but ... You give the regulator what voltage you want, and the regulator gives out 5v. The Pi takes what current it wants, and the regulator tak...
by Burngate
Mon Apr 01, 2019 11:01 am
Forum: Beginners
Topic: Input Relay Board
Replies: 22
Views: 498

Re: Input Relay Board

For example: if I put a wall switch in my house and turn it off, if I test for voltage at the light, guess what voltage I will get? 0 volts! Every time! On every switch in the house! If you get 0.05 VAC on the output of a house switch you have a defective switch! ... And another thing: Active LOW?!...
by Burngate
Mon Apr 01, 2019 10:25 am
Forum: General discussion
Topic: Pi 4 questions
Replies: 166
Views: 7196

Re: Pi 4 questions

Yes, a counter would be needed; powering up it would enable SD0, with a pulse to swap to SD1 then SD2 ... It's becoming too complicated ... maybe an add-on extension board to extend the single slot to multiple slots ... which would be just as useful for earlier Pis. So it's actually off-topic for Pi...
by Burngate
Mon Apr 01, 2019 8:47 am
Forum: General discussion
Topic: Pi 4 questions
Replies: 166
Views: 7196

Re: Pi 4 questions

As for multilple SD card sockets - each one woudl require a separate SD card interface on the SOC, unless we added a jumper. A transistor driven from a GPIO and feeding pin 4 (Vcc) of each socket would solve that. And multiple sockets, the first as default holding a derivative of NOOBs with the res...
by Burngate
Sat Mar 30, 2019 7:16 pm
Forum: Automation, sensing and robotics
Topic: raspberry pi connect button problem
Replies: 4
Views: 252

Re: raspberry pi connect button problem

At a guess, the other pins labelled + and - are for an in-built LED and can be ignored.
by Burngate
Sat Mar 30, 2019 7:13 pm
Forum: Beginners
Topic: Getting started. Something wrong
Replies: 14
Views: 410

Re: Getting started. Something wrong

mistofeles wrote:
Sat Mar 30, 2019 8:22 am
The device is an older version with 'shirt' GPIO connector, LAN and RCA connector.
Perhaps for 'shirt' read 'short'? Perhaps Pi 1
by Burngate
Sat Mar 30, 2019 10:11 am
Forum: Troubleshooting
Topic: no boot - always red light - rpi3b+
Replies: 9
Views: 231

Re: no boot - always red light - rpi3b+

edimi wrote:
Fri Mar 29, 2019 7:40 pm
The point is how to prove it :?
Depends where you are, but my understanding of it is, in the EU at any rate, within 6 months of the sale, you don't have to prove anything, the supplier has to prove your wrong-doing

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