Hi!
I want to water my plants on my balcony while i'm not there.
I bought an electrovalve which works with 12v, 8W, and I want to supply it, or not, with a laptop. I thought the serial port would have do that, but I can't get any current from it, according to my voltmeter.
Is it possible, do you have any ideas?
This project is probably above your current understanding of how serial ports work.
Serial ports are communication "devices"
They are really only used to send and receive data.
What you need is a controller board hooked up to the valve.
valve-->controller board-->serial port
The serial port sends a signal to the controller board.
The controller board sees the signal and tells a relay to turn on/off the valve.
The laptop would be used as a power supply and a timer
You're right I don't know serial ports much..
I just want to get some 12v from my laptop. I thought I would have used a linux command like rtcwake, which wakes the computer and that way the 12v from anywhere would be active. And then, 1h later the computer would go back to sleep for 23h.. something like that. I know there is some 12v on the cd drive, but it would be easier to get it from an external port
>>999567
An arduino or similar would be better suited for this
also, you can easily found tutorials
>>999579
You aren't going to get 12v from any external port on the machine. Especially not 8w worth.
It sounds like you're trying to re-invent the wheel here, instead of buying a reliable, and readily available clock timer.
>>999583
Buying a timer is a solution but not a Diy one...
If I can't do another way, with my laptop, I'll probably do that.
>>999583
You said not 8W, but I have a relay in stock, if needed, which comes from a car, it works with 12v.
>>999590
You still don't get it. You obviously have no idea how a relay works.
YOUR LAPTOP CANNOT SUPPLY 12V @ 8W TO THE VALVE THROUGH ANY PORT.
Find another way that isn't above currently level of understanding.
Just get one of these
<----------------
It will save us all from getting headaches.
>>999596
Sorry if I annoy you.
But.... why can't I supply my relay with a low 12v current from my laptop, and so get 12v/8W from an external 12vDc supply? The laptop would act as a timer.
>>999599
Seems to be very complex to get some 12v from a laptop
>>999567
I've never done anything like this, but a quick googling suggests that serial ports can, hypothetically, give you 12 volts, but nothing even close to the wattage you need. They're for data transfer, not powering machinery. Read this if you want:
http://www.epanorama.net/circuits/rspower.html
The laptop's optical drive is a far better candidate, but that depends on your laptop. A standard SATA connector should be able to give you 12V and 1.5A, according to the standard, but micro SATA and slimline SATA, widely used in laptop drives, lack the 12-volt output. And even if you do find that 12 volts somewhere, remember that the laptop definitely wasn't designed to do what you're trying to. Test your setup before you leave it alone for extended periods of time, in case it catches fire or something.
The last option would be to hook your valve directly to the laptop's power supply, but I'm not really qualified to tell you how the laptop, the supply, or the valve would deal with that.
Good luck!
>>999600
yes. But some relays can also be activated with a 5v signal.
relays can help you isolate from the higher voltage source.
All that said, good luck getting it done without any GPIO. Your best bet is to simply use a store bought timer if you're on a budget, or if you want to learn: arduino/rpi/generic microcontroler/generic sbc/555 timer.
http://www.amazon.com/LCUS-1-Intelligent-Control-Switch-Onboard/dp/B01CJHJSHC/ref=sr_1_5?s=industrial&ie=UTF8&qid=1464380941&sr=1-5&keywords=usb+relay
>>999614
USB is 5v, use relay.
Or even better - use arduino.
