Economical The 5½-digit 6485 Picoammeter can measure currents from 10fA to 20mA, with a reading rate of up to 1,000 per second. The 6487 Picoammeter/Voltage offers higher precision and faster rise time than the 6485, a 500V source, and a damping function for use with capacitive devices. The 6482 dual-channel Picoammeter/Voltage source provides higher measurement resolution than the 6485 or 6487, along with two independent 30V voltage bias sources.