Powering a 6v project with a 9v battery? (UPDATE: HELP!!!)

[inverseroom]

I'm going to build this 555 "theremin" project, but it runs on 6v (4 AA batts).  I would love to jam it into a 1509B.  Is there some simple change I could make to the circuit that would allow it to run on 9v?

[amz-fx]

The circuit will likely work from 9v...  but to avoid changing any operating parameters you could put 4 diodes in series between the 9v and the power input to the circuit, and they will drop approximately 0.65 x 4 = 2.6v leaving you with 6.4v power.

1N4001 diodes will do the job.

You could use a 3v zener diode in series to get 6v instead of the four 1N4001.

-Jack

[inverseroom]

The circuit will likely work from 9v...  but to avoid changing any operating parameters you could put 4 diodes in series between the 9v and the power input to the circuit, and they will drop approximately 0.65 x 4 = 2.6v leaving you with 6.4v power.

1N4001 diodes will do the job.

You could use a 3v zener diode in series to get 6v instead of the four 1N4001.

-Jack

Thanks, Jack!  What about 1N914's?  I've got tons of those...

Or perhaps I will return to Rat Shack for the zener.  :oops:

[inverseroom]

...or, alternately, could I just let the thing eat 9v and change one of the resistors?  Or perhaps I should just install a pitch adjust pot instead.

Maybe this is a good opportunity for me to experiment for a change instead of getting my answers from a messageboard!

[petemoore]

They're 'smaller'...I'd look up the data sheet or trust that 1n4001's suggested will work...I think any 1n400x will work, I get them from in computer monitor boards...big square-round black honkerz, then test with the DMM for voltage drop, I use 'em for reverse battery connection protection and other uses.

[inverseroom]

OK guys, I tried this circuit on 9v and fried the 555 right quick.  (It did work for awhile, though it was INSANELY LOUD and even completely covering the phototransistors didn't shut the sound off...but then it nearly burned my finger when I touched it.)  So I got myself some 1N400x diodes.  To test, I hooked them up in series to the positive terminal of the battery and tested the result on the multimeter.  To begin with, the NiMH battery I'm using says "8.4v" on it but actually tests at around 9.5.  And from there, the four diodes only got the voltage down to 8.0v, a total of 1.5v.

What's up with that?  To complicate matters, on the package for 1N4005 diodes it seems to say that it's supposed to attenuate 1.6v PER DIODE!

Very puzzled.  Help?

[toneman]

555 should work fine either way.
it's rated to 18V so 9V should work fine.
might have to increase timing  resistor(s) 2 get the same freq.
power diodes(1n400x) are better than signal diodes(1n914, 1n4148)
try it again................wear safty goggles.... :shock:
T