Check out my experiences in this thread with that exact relay.rooster wrote:ok, to half answer my own question, I realised I'd bought one of these a few weeks ago in the hope it might be useful and then forgot about it...
http://www.ebay.co.uk/itm/2-Channel-DC- ... 163wt_1045
but...how do I know if the PI can provide the power to the relays? I assume the GPIO pin is fine because its supplying a small current to the transistor (so will be less than the 20mA), but I can't see a) the current the relay needs to operate or b) the current that the PI can supply.
Because you need to 'boost' the 3V3 level to 5V to turn OFF the input on the relay card, Use something similar to fruitloaf circuit, but it depends on what the actual relay card has on its front end.rooster wrote:Hi techpaul
This is the module
http://www.ebay.co.uk/itm/2-Channel-DC- ... f3305#shId
the circuit diagram is shown towards the bottom of the page. I was connecting VCC and GND to the +5V and GND of the PI and IN0 to GPIO0. The relay works when IN0 is directly connected to the GND or +5V but wont be driven by the 3.3V of the GPIO
Your relay cards have the diode on already.rooster wrote:and where/which direction would the diode go on your circuit diagram?
ok, thanks. if maplin has transistors at least i can get this to work this afternoon!techpaul wrote:Your relay cards have the diode on already.rooster wrote:and where/which direction would the diode go on your circuit diagram?
The suggested circuits go between the GPIO output and your relay card
Like nearly all sites including ebay ones the phot does not match the circuit.Bencom wrote:The YwRobot relay circuit can be found here.
http://arduino-direct.com/sunshop/index ... tail&p=181
Yes you will need a buffer in simplest form on my diagrams for EACH relay.I have a YwRobot 4 Relay and although it works is is very bad for the RPi.
I have a opto module on the way but this will require a buffer just like the pnp relay.
Perhaps the relay above will be the solution. Thankfully my board survived the ordeal.