Can I power a 6v circuit from a 9v battery?

[mattpocket]

http://aronnelson.com/gallery/seljer/7809power_copy

Sorry I didnt post the link, I had to rush off and didnt have time to find it...

I think I can just sub the regulator...

Do I need to worry about standoffs, enclosure, heatsinks for this one? I thought they all had to be specific kinds for powersupplies.

Matt

[petemoore]

  A regulator dropping 'alot' of voltage can get hot quick, be sure if you put a pot to adjust V, you have it 'up' to start with and check heat dissipation, you wont need a heat sink to get 6 volts from 9v. I'm at the ready [w/right hand] to cut supply input, testing for heat with my left hand when I first apply power.

[grapefruit]

Have you checked the current requirements of the speak and spell? If you have a bench supply I'd set that to 6V and power up the circuit and measure current draw. If it draws much more than 100mA you should really have a heatsink. As has been said, it may not be a problem with low Vin-Vout difference, but I'm guessing the S&S chews a bit of power.

If you can't get a 7806, you could use a 7805 (or LM2940) with two diodes in series between the GND pin and GND, with anodes coming from GND pin. This will probably give slightly more than 6V but no more than fresh batteries.

Cheers,
Stew.

[mattpocket]

Thanks!