SCRs will not turn OFF until the AK voltage is removed IIRC. So they aren't very suitable for switching DC items such as relays.
So if I understand you correctly, once I have powered the gate, even if I remove the gate power, it still remains on, until I stop the flow of the current between cathode and anode ?
I also have a bunch of 2N2222A NPN transistors ( data sheet at : http://www.datasheetcatalog.org/datasheet/SGSThomsonMicroelectronics/mXyzzyw.pdf
) but not being an electronics person, I can't understand the jargon.
Any chance someone can tell me what I should be looking at to get the values for :
1. max V and A that can pass through the transistor.
2. V and mA required to activate the transistor.
I guess the pin to base resistor should be calculated in much the same way as for an LED to reduce the voltage to that required by the base ?
Also, would this type of transistor only pass thru current when the base is powered - so when I cut the base power, it breaks the flow thru the transistor ?
Many thanks in advance for any replies.
ps .... lets scrap this idea and do the right thing. I have created a new post :http://arduino.cc/forum/index.php/topic,58059.0.html