Not sure which forum to post this, so I figured I’d try here.

I’m installing a small Bluetooth amp in hot rod, and would like to have a power indicator light on the dashboard for when the amp is turned on. The amp has a small led power indicator soldered onto the board itself, so I have two questions:

1) would the power running to that little led be sufficient to run a larger led (described as 12v) if i desoldered the small led and soldered the larger led’s wires in place?

2) if not, could I use the small led’s power to trigger a relay for the larger led, and what type of relay should I use?

Thanks for any advice.
Nick

 

The supply for a standard LED will not drive a 12V LED or relay.
You could extend the wires from the existing LED and connect a similar small LED on the dashboard.
If you want to drive a bigger, higher voltage, LED then you could use a MOSFET controlled by the original LED voltage and switching the larger LED.

 

If you have access to the circuit board, you could connect your 12V LED to the + and - on the board, after the power switch.
Regards,
Keith

 

AlbertHall - the MOSFET solution looks like it'll work, thank you. I have similar project for a console radio, do you know of a component that can be used in an AC application?

Keith - I hadn't thought of that, good point. This is a small amplifier that works on a range of 5-27 volts, would the draw from the LED cause any performance issues with the amp?

Thanks to both for your input.
Nick

 

I have similar project for a console radio, do you know of a component that can be used in an AC application?

If you have a switched 110V or 230V AC then probably the easiest is a neon with a suitable resistor (100k/220k). These are available to fit a panel with the resistor built in.

 

Keith - I hadn't thought of that, good point. This is a small amplifier that works on a range of 5-27 volts, would the draw from the LED cause any performance issues with the amp?

If you are supplying it from the car battery, and connect it across the switched 12V supply on the circuit board before the voltage regulator it will not affect the performance of anything. The 12V led indicator presumably has a built in current limiting resistor and will only draw about 5mA.
Keith