Hi
Thanks for the replies.
I don’t have a smart phone that can be used for this but I have (tentatively) been investigating a potential Arduino/ Launchpad/ Raspberry PI etc solution. They “appear” to be a likely option. I am thinking I will need 8 output pins to switch the relays, does anyone know if an Arduino etc touch screen setup would have enough pins available for the pin-relay switching and screen connection?
Relays.
I am currently leaning toward a nominal 5 volt DTDP latching style of relay. My reasoning is simply that I have 5V available, DPDT means fewer relays and self latching appeals because it removes the need to always have each active relays coil energised. I am thinking of trying 4 relays so I can run 2 separate unbalanced stereo inputs with both being able to independently switch to 2 separate outputs.
Zettler AZ832P2–2C–5DE, 5V
http://www.azettler.com/pdfs/az832p.pdf HONGFA HFD3/5-L2S1R, 4.5V
http://www.azettler.com/pdfs/az832p.pdf What about relay minimum contactor load, as far as I can tell the Zettler doesn’t state a minimum load but the Hongfa is classed as a Signal Relay with a contactor minimum listed as 10mV and 10 micro amps (I have been trying to read data sheets
). How critical is a minimum contactor load, would the Zettler serve my purpose? I am having trouble finding suitable relays, there are lots of non latching single pole options but very few DPDT latching types (that is if I don’t want to buy 20 or more of them). Also, is contactor bounce an issue, when dealing with such small current values?
Connecting the relays.
I have seen some (expensive) premade multi relay units labelled as “passive” with only one diode per relay coil. Alternatively I have seen a lot of examples with many being labelled “for Arduino etc” applications where each relays set (and reset) functions are switched via circuit using transistor(s), resistor(s) and diode and what I think is an optocoupler, alternatively I have seen discussions suggesting a circuit looking similar to this:
So, why are some assembled relay boards labelled as passive? Is it because they don’t have active components (e.g. transistor) connected?
Since my choice of relay type means I may have to assemble the relay board, what is the expert opinion about each relays associated circuit, is the type linked to above acceptable or is it better to use something like the optocoupler versions, e.g. 3:42 and 8 mins
Regards.