Author Options:

What do I have to change to use a 9v battery in this circuit? Answered

This is the light theremin from Make Projects http://makezine.com/projects/light-theremin/

It uses 4 AA batteries, so 6 volts.  Can I use a 9 volt battery instead?  If so, what would need to be changed in the circuit?


If you are making a theremin change nothing other than the battery holder of course, just remember these work best indoors with a single light source.

there is no problem about the battery holder:

Nothing. The 555 timer should be able to take up to 16V.

BTW the 4x AA batteries will last longer then a conventional 9V battery.

Thank you!
Do you know about how much longer? I just wanted to use a 9v because I already have a clip/holder for it and don't have one for 4 AAs

An AA cell has a volume of ca. 7.5cm³ for 6 cells that would be 45cm³, a 9V block has a volume of ca. 13cm³. So the 6 AA cells should last about three times as long as the 9V block - given the same chemistry and quality.

You can get a battery holder for the AA's which uses the same battery clip as a 9 volt PP9

Just making sure you where not under the impression that a 9V battery would be a better option here.

A 9V battery only carries .55 Ah while a single AA has about 2.4 Ah in it.

A battery’s amp-hour rating indicates the total amount of energy it will deliver at a constant rate of discharge over a period of 20 hours before it reaches a voltage at which it is stone dead for all practical purposes.

Read more: http://www.answers.com/topic/amp-hour-ratings#ixzz2XI4oRK3e

Whoops? Why didn't I see your answer before I replied? You're correct, of course.

Didn't check it completely, but it should work. Just connect the battery and try. It will not break anything, that's for sure - the 555 can work with even high voltages.