Anyone got any super simple circuit designs for converting 1.5 V DC to 9 V DC? Maybe something that uses a couple of transistors would be good?
If you just need a few milliamps, it looks like maybe the NCP1403 would do. Otherwise, TI doesn't seem to have anything besides the TL499A; maybe Linear Tech or Maxim or Micrel or National Semiconductor would have something useful.
edit: Linear has the LT1615-1, looks promising but pricey as most of Linear's stuff is. I don't like Maxim (have been burned by pricey unobtainable products too many times).
National has the LM2621.
update (based on comments):
Consider using the 1.5V of an AAA battery directly, along with a low-voltage version of a 555 (e.g. TLC551 -- not a typo, it's a little different from TLC555 -- or LMC555 or ZSCT555), and a buzzer/piezo rated at 1.5V.... the latter is kinda difficult to find (I guess they spec 15Vp-p usually) and we ran into the same problem on a project at work. You'll get twice the peak-to-peak voltage if you drive both sides of the piezo. Drive one end from the 555 directly, the other end from an inverted version of the 555 output: pick a 74xx14 from a logic series that can run off 1.5V and has high drive capability. You can generally parallel up the output of inverters with identical inputs (for a home project fine, on a "real" project i'd probably put some 1-5ohm resistors in series to limit short circuit current somewhat)
It may not be as LOUD as running the piezo off 9V but maybe that's ok.... :-)
I did a brief review of the TL499A, and I believe (from the data sheet) it will do what you need:
There is a DIP package available, and the data sheet gives a pretty complete application example on page 4. Mouser shows these chips available for $1.50 with plenty of availability.
You should definitely figure out your current requirements as well. Handy charts are in the data sheet to help you determine if this chip can supply the current you need.
I had a look at the 551 timers and I don't think they will be that loud when hooked up to a regular piezo buzzer. So I've decided to try and boost the voltage, I couldn't find most of the ICs available locally at short notice, but I did manage to find some NCP1403s that can be delivered tomorrow. So I'll try them out with the trusty 555 timer and I'll let y'all know if it works well. The only thing I'm worried about is the lack of current!