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by Z80 Refugee
Fri Jun 22, 2018 9:00 am
Forum: General discussion
Topic: Documentation for beginners
Replies: 34
Views: 3431

Re: Documentation for beginners

Sure, but the OP didn't find them.
by Z80 Refugee
Fri Jun 22, 2018 8:47 am
Forum: Beginners
Topic: New to Raspberry pi, what do I need to know to start a project?
Replies: 9
Views: 975

Re: New to Raspberry pi, what do I need to know to start a project?

So you've answered your own question. Look at what other people have done and build on that (never try re-inventing the wheel, it's a waste of resources),
by Z80 Refugee
Fri Jun 22, 2018 8:44 am
Forum: General discussion
Topic: Documentation for beginners
Replies: 34
Views: 3431

Re: Documentation for beginners

Why not? Even if it was locked and just had that references post in it, it would provide a pointer to the information.

You want the information to be seen, so provide every possible means for someone to find it.
by Z80 Refugee
Fri Jun 22, 2018 8:37 am
Forum: Advanced users
Topic: Alarm System (VISONIC) - input wired & output pgm connections
Replies: 15
Views: 2235

Re: Output Dry contact

I've got a VISONIC alarm system which allows to install a daughterboard for trigerring output signals through dry contact... I'd like to use a raspberry GPIO in order to read those signals through python GPIO library. Your "dry contacts" are just electromagnetically-operated switches (ie ...
by Z80 Refugee
Fri Jun 22, 2018 7:57 am
Forum: General discussion
Topic: Documentation for beginners
Replies: 34
Views: 3431

Re: Documentation for beginners

https://www.raspberrypi.org/forums/viewtopic.php?f=63&t=51436 The reason you might not have found that thread is because "General Discussion" isn't the most obvious place to look. It would help if there was a "Getting Started" section under "Community", or the threa...
by Z80 Refugee
Fri Jun 22, 2018 7:51 am
Forum: Automation, sensing and robotics
Topic: Pi Powered Fan
Replies: 26
Views: 3609

Re: Pi Powered Fan

You can only turn off all the USB ports and the LAN chip using these mothods, there is no way to switch individual USB ports off. Thanks, that's what I thought. No good if you require any other USB device to work. Nonetheless, it is interesting to know projects (that don't need USB) have a source o...
by Z80 Refugee
Thu Jun 21, 2018 7:46 am
Forum: Advanced users
Topic: Documentation bugs: RPi2&3 GPIO electrical specs
Replies: 133
Views: 22328

Re: Documentation bugs: RPi2&3 GPIO electrical specs

I meant measure with the precision required to caracterise the performance in a production test environment for guaranteed specifications. I agree it's not difficult to sample for a rough "typical" value - and I might just try that: it would be interesting to build an oscillator using GPIO...
by Z80 Refugee
Thu Jun 21, 2018 7:38 am
Forum: Automation, sensing and robotics
Topic: Pi Powered Fan
Replies: 26
Views: 3609

Re: Pi Powered Fan

Wow! (proxy for something more colourful) Thanks for that. I made the mistake of trusting the published schematics and did not spot they were incomplete - so actually they are not worth the paper they are printed on. :x

Let the hat fest commence...
by Z80 Refugee
Wed Jun 20, 2018 3:53 pm
Forum: Automation, sensing and robotics
Topic: Pi Powered Fan
Replies: 26
Views: 3609

Re: Pi Powered Fan

pcmanbob wrote:
Wed Jun 20, 2018 2:58 pm
I think what the code is supposed to do is turn off the 5v to the USB ports, I know this is possible but I am not sure its the same for all pi models.
Is it? Since when? Please refer me to something that says so, and then I'll eat my hat.
by Z80 Refugee
Wed Jun 20, 2018 2:41 pm
Forum: General discussion
Topic: Using raspberry pi to measure angle newbie
Replies: 5
Views: 1840

Re: Using raspberry pi to measure angle newbie

Geejayrail wrote:
Wed Jun 20, 2018 1:23 pm
I'd just like to know if it would be possible on the platform?
If you mean without any additional parts (like you can with an Android/iOS phone), the answer is no.
by Z80 Refugee
Wed Jun 20, 2018 2:37 pm
Forum: Automation, sensing and robotics
Topic: Pi Powered Fan
Replies: 26
Views: 3609

Re: Pi Powered Fan

I don't have an answer to that one - maybe you should put a query in the discussion area for that MagPi article. I hesitate to say it, but it looks like a scam to me. A USB connector has a supply of 5V, handy for powering accessories on the desktop (the real one) because most desks have a computer a...
by Z80 Refugee
Wed Jun 20, 2018 12:25 pm
Forum: Beginners
Topic: Power 12v electromagnet and control it with raspberry
Replies: 2
Views: 483

Re: Power 12v electromagnet and control it with raspberry

That seems to be the way these days: "oh, I've got an assignment to work out how to do this, I'll go onto a forum and ask to be spoon-fed everything instead of researching the published literature for myself" - and that seems to apply all the way up to PhD level. So, in answer to this quer...
by Z80 Refugee
Wed Jun 20, 2018 11:08 am
Forum: Advanced users
Topic: Documentation bugs: RPi2&3 GPIO electrical specs
Replies: 133
Views: 22328

Re: Documentation bugs: RPi2&3 GPIO electrical specs

Exactly. If you need a specific hysteresis, build it into your signal conditioning and don't rely on any inherent input noise immunity - which has been my point but people seem to want to pick it over. I could have gone into vast detail about how all signals have some noise, but for brevity... Digit...
by Z80 Refugee
Wed Jun 20, 2018 9:06 am
Forum: Automation, sensing and robotics
Topic: Pi Powered Fan
Replies: 26
Views: 3609

Re: Pi Powered Fan

I don't get it. Aren't you guys missing something obvious? A standard "USB Fan" is only USB powered , not USB controlled . I can't see anything here which is able to turn the fan on or off by program control, because all you actually have is a 5V fan running off the power from a constantly...
by Z80 Refugee
Wed Jun 20, 2018 8:57 am
Forum: Advanced users
Topic: Documentation bugs: RPi2&3 GPIO electrical specs
Replies: 133
Views: 22328

Re: Documentation bugs: RPi2&3 GPIO electrical specs

It's really quite simple: do not apply a noisy signal to an RPi input and expect reliable results. Hysteresis protects inputs from a slow monotonic transition, not a noisy one. All digital systems are susceptible to metastability. If an input isn't held at a defined logic level for the specified len...
by Z80 Refugee
Wed Jun 20, 2018 8:35 am
Forum: General discussion
Topic: PMs being turned off from June 13
Replies: 54
Views: 11379

Re: STICKY: PMs being turned off from June 13

I agree, and this is the only forum I use that has taken this approach.
by Z80 Refugee
Tue Jun 19, 2018 3:46 pm
Forum: Graphics, sound and multimedia
Topic: How do I add a headphone jack?
Replies: 16
Views: 2996

crofter wrote:
Tue Jun 19, 2018 3:24 pm
this will not work for a bridge amp r + - and l + - should never be connected to each outher or it will blow up the amp chip
If you had read the whole thread you would know we've already been there, and...
Benadryl wrote:
Fri Jun 15, 2018 9:08 pm
There is no resistance between the two negatives meaning I can combine them.
by Z80 Refugee
Tue Jun 19, 2018 12:59 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Beginners Guide to Wiring Things to the GPIO
Replies: 0
Views: 24901

Beginners Guide to Wiring Things to the GPIO

(This post was originally part of the first post in my thread about Forth , but I have now split it out so I can refer to it separately.) WARNING: Hardware is not software. The worst that can happen when mucking about with software is you might corrupt an SD card or something. Generally, if you get...
by Z80 Refugee
Tue Jun 19, 2018 12:41 pm
Forum: Advanced users
Topic: Documentation bugs: RPi2&3 GPIO electrical specs
Replies: 133
Views: 22328

Re: Documentation bugs: RPi2&3 GPIO electrical specs

Hysteresis is useful when taking an input voltage that varies relatively slowly - eg a switch debouncing circuit. In that context, I take back what I was saying about hysteresis being irrelevant without a specification (and it might as well be there as not). Hysteresis specifications are vital if de...
by Z80 Refugee
Tue Jun 19, 2018 10:36 am
Forum: Advanced users
Topic: Documentation bugs: RPi2&3 GPIO electrical specs
Replies: 133
Views: 22328

Re: Documentation bugs: RPi2&3 GPIO electrical specs

Without a specification, the hysteresis is practically irrelevant*. Anyone needing input hysteresis in their project should provide their own. * I've changed my mind. See later post: Hysteresis is useful when taking an input voltage that varies relatively slowly - eg a switch debouncing circuit. In ...
by Z80 Refugee
Tue Jun 19, 2018 8:42 am
Forum: Troubleshooting
Topic: keyboard configuration problem?
Replies: 9
Views: 939

Re: Weird problem!

The # is more correctly called an "octothorp" not "hash", "pound", "sharp" or "hashtag". "Octothorp" is the technical name for the glyph. Almost nobody actually calls it an octothorp, because if they did whoever they were speaking to would...
by Z80 Refugee
Mon Jun 18, 2018 9:39 am
Forum: Beginners
Topic: New to Raspberry pi, what do I need to know to start a project?
Replies: 9
Views: 975

Re: New to Raspberry pi.

What sort of project do you want to do?
by Z80 Refugee
Mon Jun 18, 2018 9:37 am
Forum: General discussion
Topic: Max Amps?
Replies: 10
Views: 8023

Re: Max Amps?

The current rating of a power supply tells you the maximum it can supply, not the amount it will supply. If the current rating is not sufficient for the load, all that will happen is things won't work properly. As long as the current rating is at least as much as you need, that's fine. It is the vol...
by Z80 Refugee
Mon Jun 18, 2018 9:30 am
Forum: Troubleshooting
Topic: keyboard configuration problem?
Replies: 9
Views: 939

Re: Weird problem!

I can't see that this has happened suddenly - maybe you only just noticed? What you describe is the standard UK keyboard layout, and I take it you're not in the UK - especially as you are talking about # as being a pound sign (we call it "hash", not "hashtag" - that's what it's u...
by Z80 Refugee
Mon Jun 18, 2018 7:56 am
Forum: Off topic discussion
Topic: Digital TC Soldering Station (UK)
Replies: 15
Views: 2280

Re: Digital TC Soldering Station (UK)

For work - which has a lot of teaching soldering - we use these Handskit Kits : $40 Canadian, which isn't much. The iron in that kit (note the Amazon ad calls it a "welding tool"!) looks similar to my thermostatic iron. You need something to measure the temperature to be able to set it ac...

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