Lost Battery Power

[meow2222]

to make it work seamlessly:

• radio has flat fixed contact areas for robustness, battery has sprung strips

• dry cells/nicads etc go thru a diode connected transistor, and the lead acid puts out a little more V, so when the external battery makes contact it takes over seamlessly.

• (Or you could use a relay with very low value R to limit the momentary i surge into the dry batteries. Use a fusible R in case the relay fails.)

• If you want you could add a comparator & LED that lights when the external batt's powering the set. Or change the display backlight LED for a bicolor and have it change colour when external power's in use.

It may be easier to use audio distribution. Once in place you can use it forever with all types of feed, and the cost & minor hassle of portable radios & batteries ends.

NT

[Davey]

Now that's a project for a rainy cold winter.......

[Grimly Curmudgeon]

Sky box on a radio channel and a cheapy FM broadcaster plugged into it?

[Grimly Curmudgeon]

Pah, NiMh will sort her out.

[Davey]

How would you delay the sound to match the timing of the digital vision? Just try listening to a radio programme on both an FM radio and via the TV, the time delay drives you nuts.

[Grimly Curmudgeon]

Radio only.