I would like to activate a portion of my circuit electronically. A single pulse should activate a portion of the circuit, and this portion should remain on until the device is disconnected from its source. A transistor wouldn't work because I would need the circuit to remain ON even when the initial pulse has faded.
I know using a 555 timer, it's possible to do this. A single "trigger" input will leave the 555 timer in its ON state until power is cut. However the 555 timer is sort of a noob tool? I'm wondering if there's a similar alternative using an op-amp or other cheaper device that could be used.
Alternatively, is a relay switch the cheapest, smallest, and best option here? What if the initial current is extremely small, like 1 mA?
Additionally... are there such things as relay switches that shut off after a certain amount of time without an activating pulse?
Kind of a long question but thanks