On Fri, 13 Feb 2009, Tom Wiltshire wrote: > The problem is that the output goes from 0V down to -0.5V and then seems to > saturate. What's going on? How can the op-amp output be saturated at only Looks to me like base-collector parasitic diode starts conducting. Antti "No boom today. Boom tomorrow. There's always a boom tomorrow" -- Lt. Cmdr. Ivanova