Re: Wave change switch as on-off switch
I've attached a picture to help make it clear what I was talking about.
Since you want 5V for your bluetooth device you can shed the extra 3 or 4V across a zener. It pays to allow for the battery going flat, or you could make a regulator, but you want it simple right ? and the bluetooth device is most likely tolerant 4.5 to 5.5V at least.
If you monitor the medium wave part of the switch, in that case the fet remains off, then when you switch to LW the fet goes on, powering the bluetooth device. Sorry about the non standard fet symbol in the diagram, look up the G,D & S connections for the fet on its data sheet.
Somebody else might like to check the idea to see if they think it will work. If it turned out that the 4.7M resistors or the wiring affected the MW band (unlikely if the resistors are close to the switch contacts) you could monitor the LW trimmers instead and then add an inverting stage after the fet to switch the bluetooth device.
|