9v wall wart is 11.8v

[moving_electrons]

I have a 9v wall wart that I would like to use with a Small Bear Electronics "Bear Face" ( http://www.smallbearelec.com/Projects/BearFace/BearFace.htm.

The wall wart is rated at 9v and 1 amp. The voltage with no load is over 12 volts. When plugged into the Bear Face it drops to only 11.8V. It is a new transformer so I think it is normal for one of its rating with a small load. I checked another transformer I had on hand.  I got similar results.

Will this higher voltage damage or shorten the life of the germanium transistors noticeably?

Should I:

1) go ahead and use the transformer, it will be fine?
or
2) find a lower amperage rated wall wart that will get pulled down to 9v by the Bear Face circuit?
or
3) build a regulated supply and baby those transistors?

Thanks for your advice.

[Regan]

I wouldn't worry about it too much.
Regan

[Paul Perry (Frostwave)]

You could drop the voltage with a resistor in series with the wart, maybe tweak a 5K pot to find the right value, then put a 100mfd electro after the resistor to ground.
I agree that the Bear Face should be able to handle 12v OK, but it won't sound EXACTLY the same as with 9v (might be better though.. who can say???)

[RDV]

You could do this.


RDV

[moving_electrons]

You could do this.


RDV

Sounds then like I can use the wall wart for now at the 12v without worry.

Thanks RDV for the schematic and part values.  I have most of the parts as I have used a similar circuit (mirrored) for a +/- 18v supply.  That one has protection diodes on it.  Your schematic caused me to explore a bit.  I see you don't need them for the 12v operation.

I am thinking of fitting it into a small plastic sealed project box with a metal lid (heatsink the LM317).