The transistors of this circuit may be the BC548 or BC549 and its power supply can be performed with voltages from 15 to 22 V. The circuit has a gain determined by the values of the components in the feedback circuit. The input connections and signal output should be shielded. Consumption is very low, on the order of a few milliamperes. If a power supply is used, it must have excellent filtration. The level of the output signal is of the order of a few hundred millivolts, enough to excite the input of most audio amplifiers. Input is average impedance. C has values between 4n7 and 47 nF.
| GAIN | 10 | 20 | 30 | 40 | DB |
| R1 | 4k7 | 1,5 k | 1,5 k | 1 k | Ω |
| R2 | 12 | 15 | 56 | 180 | kΩ |
| R3 | 470 | 560 | 330 | 680 | Ω |
| R4 | 1,8 | 2,2 | 2,2 | 2,2 | kΩ |
| R5 | 1,2 k | 470 | 270 | 220 | Ω |
