It was surprisingly hard to find those converters for German and English to SAMPA.
Ok, the German one is even linked in Wikipedia (even in the English version) but nevertheless, just googleing for SAMPA converter was not very helpful. So here they are, for my later research and may be for the web wanderer...
UPODN: Turn your text into fənɛ́tɪks here
Rainers Horen: Schreibmaschine zum Konvertieren von Text zu IPA und SAMPA