Sorry, data sheet. There is no manual.jimjulian wrote:
First : your 'manual' is not a manual, but a data sheet.
Second : Your second link is dead.
I was being modest. I know enough about electronics to get through this assignment. I'm not in an electrical engineering course, so I included all of the "I know nothing" for hopes that I could get an easily explained guide.jimjulian wrote:
Third : If you don't know anything about electronics, you're in over your head.
My favourite. How did you deduce that I didn't own a volt-ohm meter? I've owned two volt-ohm meters in my life, no idea where they are now.jimjulian wrote:
Fourth : If you don't have a volt-ohm meter, you don't know anything about electronics.
I'm sure.jimjulian wrote: Hope this helps.
DougieLawson wrote:You need 12V to energise the relay coils, you need 5V to activate the opto couplers that switch the relays on or off. The most important thing is to pull that jumper between Vcc and JD-Vcc off the pins or you risk feeding your RPi 12V (which WILL let the magic smoke out and WILL cost you £35 for a new RPi).
It's not really a device that's suitable for use with a RPi, it would work better with an Arduino or driving it with a MCP23017 (running at 5V). You could drive an Arduino or an MCP23017 from your RPi.
If I were you I'd send it back for a refund and get an alternative that runs at 3.3V.
Seeing as the 'logic' component is 5v, I'm guessing it's not possible, because although I can power the coils independently with 12v, I can't get a Pi to output 5v from a GPIO pin. I've seen a lot of people online who are supposedly doing something with it though… maybe I was wrong."Removing the jumper lets you have isolated supplies, one for the the Arduino and another completely separate one for the relays. Separate supplies provides some extra protection against mains volts getting back into the microprocessor. But this extra protection is mostly illusory. The pcb tracks on the back of the board are quiet close and nothing will protect you against a lightning strike on the power line outside your house."
Now might be a good time to either find one of them or get another one, perhaps, if you are in the US, at Harbor Freight, which often gives them away for free, although you may need several to feel a reasonable certainty that they are actually displaying usably correct values.polarbeared wrote: I've owned two volt-ohm meters in my life, no idea where they are now.
More detail on the remote contacts you tend to switch using relay contactspolarbeared wrote:Hi everyone, I'm very new to electronics, and I realise this is a question that's been asked a lot, but I still have no idea.
I was at Jaycar electronics today and I mistakingly purchased an 8 channel relay board which switches at 12 volts.
I have 12v DC external power supplies available (those ones you plug into the wall). Before I attempt to wire this thing up and damage a university loaned RPi2 I have 3 questions;
1. Is this even possible? – supplying 12 volts to a relay externally and somehow controlling the switch on an off with GPIOs?
2. Are relays highly resistive? I understand that you can put up-to 250v through this thing, and I was really just wanting to close a contact on a remote control…
3. If you think I should return it, what should I get instead? I'm trying to close possibly 5 different contacts on a remote control. Not anything too big.
The manual for the device I bought:
Would this be a solution? Why does it need a 9v battery?
http://electronics.stackexchange.com/qu ... transistor
I'm just shorting a very small coin battery operated circuit switch. I don't think I'll be using a relay now, so I guess an optocoupler.boyoh wrote: More detail on the remote contacts you tend to switch using relay contacts
Take in mind that relay contact have a bad habit of bouncing, Your remote
will see these as repetitive pushes. Look into using solid state ( Transistor
You can't drive 5V electronics from 3.3V GPIO pins that are rated at 16mA. You'd need to switch something at 3.3V that can then switch the relays at 5V. That's either going to be a collection of transistors, an I2C MCP23017 or opto-couplers.polarbeared wrote:
Seeing as the 'logic' component is 5v, I'm guessing it's not possible, because although I can power the coils independently with 12v, I can't get a Pi to output 5v from a GPIO pin. I've seen a lot of people online who are supposedly doing something with it though… maybe I was wrong.
Do relays provide too much resistance for me to pass a very small current through its contacts? Like a remote controller?
Candyjet wrote:This may be of use to you. I was also struggling with relays, eventually solved with optocoupler. At the end of the post there is a photo of how I got it to work