Digital Picoammeter 

• Measures current down to 1pA

• All solid state and IC design

• Very low offset current

• Built-in computer interface

Introduction  

This is a very versatile multipurpose equipment for the measurement of low dc currents. It has 6 decade ranges with 100% over-ranging from 10-9A to 10-4A. For the ease, readings are directly obtained on a 3½ digit DPM.

The instrument uses a well designed precision FET input electrometer operational amplifier AD549, which offers the lowest input bias currents (50fA with 10fA ±5V supplies) available in any standard operational amplifier AD549,which offers the lowest input bias currents(50fA with ±5V supplies) available in any standard operational amplifier.The excellent characteristics of AD549, ultra low bias current, low offset voltage, low drift and low noise have been fully utilized to obtain best results in the present picoammeter. The first operational amplifier AD549 is used in low level current to voltage configuration and the output has been directly read on a 3½ digit panel meter. The instrument is capable of accepting either polarity of the input current. Well regulated power supplies are incorporated to use the instrument upto 10% changes in a.c. main’s voltage

Computer Interface

The unit can be connected directly to a PC through an USB. Data Access And Control is a built-in interface which gives user an option to store a value as displayed on the meter and tabulate it by the click of a button on the screen. Alternatively the data may be automatically entered into a table at user selectable interval. An 'END' button on the screen terminates the automatic tabulation.

The Data stored in the table may then be displayed as a graph on the screen and may also be stored in an excel file for further processing. The software supplied with the unit is menu driven and simple to operate

Applications

• Current from Photomultiplier tubes, Photometers etc.

• Leakage currents in solid state devices.

• FET gate and tube grid-current.

• Current through very high resistance’s in conjunction with a power supply.

• Potentials across semiconductors, piezoelectric system & pH/plon sensitive electrodes

• Electrical conductivity of air

• Very low current oxygen sensors

Specifications