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by Burngate
Mon Jul 16, 2018 5:30 pm
Forum: Automation, sensing and robotics
Topic: Controlling homemade solenoids using Rpi Z W
Replies: 52
Views: 803

Re: Controlling homemade solenoids using Rpi Z W

According to https://toshiba.semicon-storage.com/ap-en/product/linear/transistor-array/detail.ULN2003APG.html the datasheet for that particular part number ... Fixed that for you. It's noteworthy that Toshiba is EOLing that part, and recommending TBD62003. That uses a FET instead of a darlington, s...
by Burngate
Mon Jul 16, 2018 9:58 am
Forum: General discussion
Topic: New firmware for the official wireless dongle
Replies: 4
Views: 189

Re: New firmware for the official wireless dongle

Might be worth fixing those two links!
by Burngate
Mon Jul 16, 2018 9:28 am
Forum: Automation, sensing and robotics
Topic: Switching ON/OFF High Current Load
Replies: 13
Views: 320

Re: Switching ON/OFF High Current Load

As Z80 Refugee says, bipolar transistors are current-driven. The ratio of (current ito collector / current into base) is called Hfe, and is quoted on the data sheet for the particular device. However, as the collector-emitter voltage drops towards zero the Hfe also drops, so you need to put more cur...
by Burngate
Fri Jul 13, 2018 5:45 pm
Forum: Automation, sensing and robotics
Topic: Controlling homemade solenoids using Rpi Z W
Replies: 52
Views: 803

Re: Controlling homemade solenoids using Rpi Z W

How about using miniature neodymium magnets as the cores? Now you've confused even me! according to earlier posts, the coil (300 turns round a non-ferrous (?) lollipop stick) pulls a pin (probably iron) down So using a magnet for the core would just hold the pin permanently down. I'd use a steel sc...
by Burngate
Fri Jul 13, 2018 5:25 pm
Forum: Add-ons
Topic: Can I switch one Pi off/on with another?
Replies: 11
Views: 237

Re: Can I switch one Pi off/on with another?

Actually, my idea was over the top - and not only that, but my hippocampus couldn't find the word "watchdog" - thanks, RaTTus Still, because the Pi isn't responding to anything, it may not be able to reset itself. So wire a 555 timer in resetable one-shot mode, and just keep resetting it. Once it's ...
by Burngate
Fri Jul 13, 2018 9:40 am
Forum: Add-ons
Topic: Can I switch one Pi off/on with another?
Replies: 11
Views: 237

Re: Can I switch one Pi off/on with another?

Maybe an over-the-top suggestion ... a Pi zero beside the 3B, on the same power supply (so the grounds are the same) and on the same network, with a GPIO connected to the 3B's RUN, and running a short script that queries the 3B. If it doesn't get a reply it briefly pulls its GPIO low ... Is it a 3B ...
by Burngate
Thu Jul 12, 2018 10:49 am
Forum: Troubleshooting
Topic: can't get AV video out properly on Pi3B
Replies: 12
Views: 238

Re: can't get AV video out properly on Pi3B

Bensimmo might be referring to https://www.raspberrypi.org/forums/viewtopic.php?f=28&t=58151 , an old favourite from way back when. though drgeoff's link is more apposite. If none of the above helps, perhaps you could take a photo of your monitor, upload it somewhere, and link to it so we can see fo...
by Burngate
Thu Jul 12, 2018 10:34 am
Forum: Automation, sensing and robotics
Topic: Two 6V motors through RPi3B
Replies: 19
Views: 416

Re: Two 6V motors through RPi3B

An obvious omission: where are your back-EMF protection diodes? See the diagrams in section 9.3.2, Figure 10 describes your particular usage. Without the diodes, you could destroy the L293D. The device in the picture is L293D which has the diodes in-built. No guarantee that the OP is using that rat...
by Burngate
Wed Jul 11, 2018 10:39 am
Forum: General discussion
Topic: Birthdays
Replies: 10
Views: 379

Re: Birthdays

This thread having caught my eye, I thought I'd have a quick squiz at the members list. There are, apparently, 237548 members, so at 25 members per page, that's 9502 pages. Sorting by number of posts, on the first 42 pages are members with 100 or more posts. Page 90 takes us to 50 posts, and page 19...
by Burngate
Tue Jul 10, 2018 6:15 pm
Forum: Troubleshooting
Topic: Problem with GPIO pins
Replies: 28
Views: 545

Re: Problem with GPIO pins

Hmm. I did rather let myself in for that one, didn't I? I've got a spreadsheet with all the GPIOs, what they're called and what they do on the various Pi's, but it's a bit out of date at the moment (every time I get close, they bring out another Pi. Tell them we DON'T need Pi 4!) Give me half an hou...
by Burngate
Tue Jul 10, 2018 6:05 pm
Forum: Troubleshooting
Topic: Problem with GPIO pins
Replies: 28
Views: 545

Re: Problem with GPIO pins

Bloody pictorials! I read (and understand) circuit diagrams. I'm with him on that! I'm not a C-coder, so I could be wrong ... In your Python code you've selected GPIO.setmode(GPIO.BOARD) But in your C code you've said #include <wiringPi.h> Now, in Python at any rate, GPIO.BOARD means the physical p...
by Burngate
Mon Jun 18, 2018 6:07 pm
Forum: Troubleshooting
Topic: keyboard configuration problem?
Replies: 9
Views: 275

Re: keyboard configuration problem?

Where I come from, braces hold my trousers up, while brackets hold my shelves up. But that's off-topic. What's also off-topic but would also be interesting: given a British pound is an L (again for Libre) where did the two horizontal lines come from? And why is a dollar sign an S, and where did the ...
by Burngate
Wed Jun 13, 2018 10:19 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Circuit using a MOSFET to control power
Replies: 7
Views: 505

Re: Circuit using a MOSFET to control power

That's my understanding, as well. What's drawn is a source follower, a.k.a common drain. Wikipedia has a page. So, as illustrated, an enhancement FET will only turn on while the gate voltage is higher than the output, limiting the maximum output voltage at 3.3V It's even worse than that - the gate-s...
by Burngate
Tue Jun 12, 2018 8:45 am
Forum: Troubleshooting
Topic: Replacement for connector mini hdmi Pi-ZeroW
Replies: 3
Views: 138

Re: Replacement for connector mini hdmi Pi-ZeroW

In a spirit of experimentation - after all, what's it going to cost you? The price of a ZeroW, a connector for a couple of quid, and a year or so extra in purgatory for the blaspheming you're going to do - RS have what looks like the right connector, part No. 163-5383
by Burngate
Mon Jun 11, 2018 5:51 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Use jumper to connect 2 GPIO in PI ZERO
Replies: 1
Views: 259

Re: Use jumper to connect 2 GPIO in PI ZERO

To return 0 when it's not connected, you need to set GPIO20 is input with pull-down, either using the internal pull-downs or with your own external one. To return 1 when it's connected to something, that 'something' must be at (or close to) 3v3. If you wish that 'something' to be GPIO26, then you ha...
by Burngate
Fri Jun 08, 2018 6:22 pm
Forum: Automation, sensing and robotics
Topic: Using a relay to connect GPIO pins and run script
Replies: 1
Views: 228

Re: Using a relay to connect GPIO pins and run script

As far as the Pi's concerned, the contacts of a relay are exactly the same as a switch, so that bit could stay the same - in fact you could keep your momentary switch and wire the relay contacts in parallel with it. Just so long as your script doesn't require the momentary switch to be opened before...
by Burngate
Fri Jun 08, 2018 5:59 pm
Forum: Off topic discussion
Topic: Is the Test / Bench Obsolete
Replies: 8
Views: 1214

Re: Is the Test / Bench Obsolete

Recently, one of the key-dongle-things for my Scandinavian car turned up its toes - fortunately I've got a second one. Tried changing batteries, no go. So off to the local dealer. But they wanted £130 !!! For a key-fob!!! Then £more to register it with the car !!! I've tried poking and prodding both...
by Burngate
Fri Jun 08, 2018 5:40 pm
Forum: Troubleshooting
Topic: Red LED only after reboot
Replies: 6
Views: 245

Re: Red LED only after reboot

It's looking more and more likely that that something untoward happened as you connected the camera. One possibility* is that the 3v3 line on the camera connector shorted to somewhere it shouldn't. Does the main chip get hot quickly? *apart from such ham-fisted-ness as dropping it in a pile of coins...
by Burngate
Fri Jun 08, 2018 9:10 am
Forum: Troubleshooting
Topic: Red LED only after reboot
Replies: 6
Views: 245

Re: Red LED only after reboot

kurtisbaute wrote:
Thu Jun 07, 2018 4:44 pm
... Did I fry it by installing the camera while the power was still plugged in?
That is certainly a possibility.
Have you removed the camera and tried it?
by Burngate
Wed Jun 06, 2018 5:57 pm
Forum: General discussion
Topic: How to force audio from jack 3.5 modifying config.txt
Replies: 2
Views: 122

Re: How to force audio from jack 3.5 modifying config.txt

https://elinux.org/RPiconfig , about 1/4 of the way down in the Video mode options section: hdmi_force_edid_audio Pretends all audio formats are supported by display, allowing passthrough of DTS/AC3 even when not reported as supported. hdmi_force_edid_audio=1 hdmi_ignore_edid_audio Pretends all aud...
by Burngate
Wed Jun 06, 2018 10:38 am
Forum: General discussion
Topic: Replacing RPi 2B -> 3B+ : Worth it?
Replies: 27
Views: 1190

Re: Replacing RPi 2B -> 3B+ : Worth it?

Is that a statement from One Who Knows, a report from the crow's nest ("still no land on the horizon, Cap'n, but it's a bit misty today"), or Nostradamus reading the runes?
by Burngate
Wed Jun 06, 2018 10:22 am
Forum: Troubleshooting
Topic: Broke off part on Raspi 3 ==> WIFI gone
Replies: 11
Views: 473

Re: Broke off part on Raspi 3 ==> WIFI gone

For what it's worth, measuring across it gives me 1.3Ω both ways.
I've no idea what's around it, but that measurement leads me to think it might be an inductor.
by Burngate
Wed Jun 06, 2018 8:56 am
Forum: Troubleshooting
Topic: pi zero cam not working
Replies: 1
Views: 67

Re: pi zero cam not working

Check that the ribbon cable is seated correctly at both ends.
Check that the 'sunny' connector on the camera board is fully home.
by Burngate
Tue Jun 05, 2018 3:34 pm
Forum: Off topic discussion
Topic: What If I Told You... You could have a bad to the box Matrix Pi
Replies: 59
Views: 3589

Re: What If I Told You... You could have a bad to the box Matrix Pi

drgeoff wrote:
Tue Jun 05, 2018 12:21 pm
(Get the approach line and speed just right and the craft will go into orbit around the planet.)
Will it?
Or put it another way - reverse everything - if a craft is in orbit, can it be ejected from that orbit without a third body?
by Burngate
Mon Jun 04, 2018 5:54 pm
Forum: Advanced users
Topic: Using Raspberry Pi to Send Composite Video to CRT - Getting Started
Replies: 11
Views: 405

Re: Using Raspberry Pi to Send Composite Video to CRT - Getting Started

Because the line frequency was so high, the saw-tooth current applied to the horizontal coils needed to change polarity very quickly, and so a large voltage was needed. That voltage was also rectified to produce the EHT. That is oversimplified to the point of giving an untrue explanation. On reflec...

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