sr555Contribute to Sunny77-uisr555 development by creating an account on . We read every piece of feedback, and take your input very seriously.SR555 Current Preamplifier. 10 VµA gain; 120 kHz (-3 dB) bandwidth; SR556 Current Preamplifier. 5 fA√Hz input noise; 1 VnA gain; SR556 Current Preamplifier. 5 fA√Hz input