can the load be placed on cathode side of a SCR? i am using bi-color LED's that have common cathode (ground) and i need to be able to latch on one side of the LED. with common cathode LED i have to control the anode side.

let me clarify (will this work).

                                     gate
                                       |
                                       |
+V----voltage drop resistor-----anode/SCR/cathode----anode/LED/cathode-----ground
                            |
                            |
                            |
                            ------- NO switch ----ground

 

can the load be placed on cathode side of a SCR? i am using bi-color LED's that have common cathode (ground) and i need to be able to latch on one side of the LED. with common cathode LED i have to control the anode side.

let me clarify (will this work).

                                     gate
                                       |
                                       |
+V----voltage drop resistor-----anode/SCR/cathode----anode/LED/cathode-----ground
                            |
                            |
                            |
                            ------- NO switch ----ground

That should work, but your gate drive voltage will have to overcome the LED drop plus the gate-to-cathode drop of the SCR. If you are triggering from a 5V source through a current-limiting resistor, it should work.
You could also trigger through a transformer with the secondary connected gate to cathode with an antiparallel diode, or you could use an optocoupler.