Americans’ response to the post-earthquake crisis in Haiti demonstrated the power of technology-enabled charity, but public broadcasters who have tried raising funds from mobile givers say it’s been a money-losing proposition so far. A handful of public stations have tried various ways of soliciting donations by text messaging. Philadelphia’s WXPN asked attendees of last summer’s XPoNential Music Festival to chip in $5 each via text message. In San Francisco, KQED made appeals during campaigns tied to Earth Day programming and 2009 year-end giving. Twin Cities Public Television made pitches during pledge drives, animated 10-second spots and e-newsletters.