This circuit uses two JFET such as the BF244 or BF245 and has an excellent gain with small intensity signals. Its consumption is very low and power can be made with voltages from 9 to 20 V. The consumption is of 8 mA with an input impedance of 1M ohm and output 5 k Ω. The level of the output signal is a few hundred millivolts sufficient to excite the input of most amplifiers. In the assembly, the components must be kept very close to each other and signal cables must be shielded. If using a power supply, it must have excellent filtration.
