Anyone know what I can use instead.

It's D1 in the schematic here:
http://www.muzique.com/images2/power11.gif

Thanks in advance

If you are sucking 1 Ampere or less, 1N400x rectifier is fine.

Higher current, you need a fatter part. 1N540x is _the_ most common 3A diode.

Any power diode rated for 3A (or greater) and 35v (or greater) will do the job.

1N5404, FR302, GP30B, HER301, BY255P, MR852 and so on. There are many available.  You can't use a common 1N4001 because it is only rated for 1A.

I just built one for a friend with this pcb and used an MR851 because that's what I had available.

-Jack

Edit: Paul, you posted while I was typing!   3A diodes are recommended since everyone eventually uses more power than they think will be required

Thanks PRR and Jack.   Just got a 1N5404. Great PCB by the way Jack, so keen to get it all together.