The photo shown is the protection circuit of the famous medium power AF amp published in Elektor magazine Nov. 1990. The circuit seems promising. But I am confused about the way the relay is driven. There are two transsistors (T26 and T25) in series handling the relay current. out of them one is a low power BC546 and the other a BC880 Darlington. Why one relatively high power darlington and the other a low power when the current to be handled seems to be the same? any thoughts? My reason and logic failed to understand this. Expect somebody shed some light on this.