Switching Power Supplies Idea

Hello everyone,

I am using a loudspeaker input to turn on a simple SR transistor data latch and use this to switch on a higher voltage circuit.
This is the circuit on yenka that I drew up (I haven't built it yet). The messier left hand side of the diagram is the bistable, the right hand side is the interesting bit - the switching transistor. This works in simulation. I know I could use a relay, but I don't have one and I would just genuinely like to know if this could work practically.
Another thing I noticed is that when I take the LHS supply voltage to 1.5V from 3V, the LED in the switching circuit stays on, can anyone explain this?
I've searched for this sort of design, but not really found anything, is there a reason for that?

Thanks for time,
TAM

when I take the LHS supply voltage to 1.5V from 3V, the LED in the switching circuit stays on, can anyone explain this?

Click to expand...

1.5V is enough to keep the second and third transistors switched on.