Here is a free DSO I have found some days ago, but due to no phone (Greeks will understand this: Ti tha ginei me auton ton OTE telospanton...?) in my house for some days (I am waiting the DSL from day to day), I could not connect to Internet to post the link. So here is the URL: http://www.chocbar.demon.co.uk/

I don't know how trustworthy this device is, but it seems that if you have the proper knowledge and you can find the components needed, it's a good solution for something cheap...

George