Raspberry Pi Forums

Mortimer

The product code you gave us relates to just the relay. What board is the relay on? Where does the board come from? Did any instruction or diagrams come with the board?

Mortimer

It looks like a solution to use a USB socket is being followed. In case there was any doubt however, the other thing to be careful of with USB powered devices, is that often the USB plug body is where electronics is hidden. It is unlikely in this case, although there might be a resistor or constant ...

Mortimer

The schematic looks to me like the lock is wired to a normally closed (NC) contact. I.e. when the GPIO output is low, the circuit is closed and the lock is fed 12V and activates. If the RPi outputs a high on the GPIO then the relay should switch over and disconnect the 12V supply from the lock. Thin...

Mortimer

Are you using a magnetic lock something like this: https://www.robotshop.com/media/catalog/product/cache/15/image/900x900/9df78eab33525d08d6e5fb8d27136e95/m/a/magnetic-door-lock_2.jpg Or a solenoid released lock: https://ae01.alicdn.com/kf/HTB1Ly0MIpXXXXXkXXXXq6xXFXXXl/Security-home-electric-door-lo...

Mortimer

Thanks for the pointer on the Ligo Bluewave DrGeoff, that also looks like a useful alternative. Not sure about the Panasonic option though. I suspect the handsets will have the same problem her current mobile phone does. Small buttons, that don't look very tactile, small screen. She simply wouldn't ...

Mortimer

After having a further rummage around the interwebs I have come across desktop GSM phones like this one: https://images-na.ssl-images-amazon.com/images/I/51nXcP1jOPL._SL1000_.jpg https://www.amazon.co.uk/F610-DESKTOP-TELEPHONE-CELLULAR-TERMINAL/dp/B071R6D2HP/ref=pd_sbs_107_3?_encoding=UTF8&psc=1&ref...

Mortimer

I am trying to find something cost effective to help my Grandmother. Sadly she has had to move into a care home after living in her own home until just before her 94th birthday. She tried to get a landline put into her room at the home, but it was going to be too expensive. She has a mobile phone, b...

Mortimer

I may be the existing PSU has sufficient surge capacity to initially throw the lock using energy stored in smoothing capacitors, but insufficient to hold the lock continuously. I don't know, without knowing the spec of the lock.

Mortimer

What lock is it?
I be surprised if 12V 1A supply is sufficient to operate it.

Mortimer

Is the Pi hanging or overloaded?

If the USB becomes too busy, then network connectivity can be lost, as it too relies on USB.

Mortimer

As Burngate suggests, some cheaper PSUs can be marketed with slightly distorted specifications. Sure it may be 5V output, and capable of delivering 3.5A, but not necessarily at the same time. It is not uncommon for the output Voltage to drop quite significantly as the output current nears the rated ...

Mortimer

If the roller blind has a piece of axle you can get to and attach a piece of threaded rod. Put a nut on the threaded rod which is attached to the slider of a linear potentiometer. As the blind is wound up and down the nut will be driven in or out on the thread and cause a change in the potentiometer...

Mortimer

The OP has: HDMI -> DVI-D (cable) DVI-D ->VGA (active adapter) VGA -> VGA (cable) It is basically working, but is stuck at 720p. It sounds to me all he needs is guidance on getting the Pi to output 1920x1200, not a new device. His HDMI -> DVI-D -> VGA setup is basically the same as the device you're...

Mortimer

SSH session timeout?
Does your client send keep-alive packets?

Mortimer

Disagree, the HDMI-DVI lead is not an active adapter, its just wires inside. His Startech adapter is going to be pretty much the same as the device you're suggesting, it just has a different plug on the end.

Mortimer

No sure that would help the OP fruitoftheloom. His setup is working just not at the resolution he wants, so I suspect a config issue.

Mortimer

Holy thread resurrection Batman!!

Mortimer

I've seen silly expanded sizes when the download hasn't completed successfully. I maybe the OP just needs to download again.

Mortimer

For a while I was doing in-service support and regularly visited a Naval training establishment in the UK. In a corridor between classrooms there was glass cabinet inside of which was the guts of a PC spread out inside. This included the hard drive with cover removed. This was always operating when ...

Mortimer

Imperf3kt wrote: ↑
Tue Nov 28, 2017 12:45 am
Its not just dust though. A lot of HDDs now include some kind of inert gas such as helium. Open it up and bye bye helium.

Not back then I don't think.

Mortimer

The message was, keep this drive in a clean place. I'm amazed you had things working at a time these spacings were 10, or more, times less. So were we frankly, especially when you consider that the reason the drive wasn't working was because the metal cover was touching the platter and stopping it ...

Mortimer

Be aware that once you open them, you can never put them back together. HDDs are manufactured in a dust free environment, such as a vacuum. Only do this if you are sure you don't want the drive. 80GB is still useful! Many moons ago, a work laptop had a hard drive problem. It was a 2.5" IDE drive, c...

Mortimer

Ha! klricks beat me to it.

Mortimer

The input to the relay board is not active-low by any chance?

Did you try setting GPIO output pin to "1" to see if it turns off?

Mortimer

Their own FAQ says it is a computer : https://www.raspberrypi.org/help/faqs/#introWhatIs

So your "microcomputer" would be correct.

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Re: Weird relay behaviour: always on if GPIO is set to OUTPUT, kinda turns off if GPIO is set to INPUT

Re: Weird relay behaviour: always on if GPIO is set to OUTPUT, kinda turns off if GPIO is set to INPUT

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