[sdiy] 9v modules?

[Colin Hinz]

On Sat, 7 Aug 2004, harrybissell wrote:

> [...] I'd even suggest that you (all) consider using a charge
> pump IC to make -9V from your battery... you can do just about ANY
> filter with that supply and the efficiency of the conversion can
> be upwards of 90% in most cases. Just don't hang anything on the
> -9V you don't NEED to and you will be fine.

I've had great luck with the MAX660 inverter IC, but it's maximum
input is 5.5V.

It seems that you can either get a high input voltage (that is,
anything much over 5V) or a high switching frequency, but not
both. A high switching frequency is nice because it means that
(a) you're not merrily chopping away at 10 kHz, like the bog-standard
ICL7660, and (b) at the higher frequencies your current spikes
should be lower.

What circuit(s) have you used, Harry? Perhaps I'm being over-worried
about the switching noise.

- Colin Hinz
  Toronto, Canada