A detector for detecting a buried current carrying conductor includes a digital signal processor, magnetic sensors, and a power supply unit. The power supply unit is a switched mode power supply which incorporates a proportional integral differential controller feedback algorithm and which is managed by the digital signal processor. The load and source voltage are monitored by the digital signal processor and a look-up table is used to control a pulse width modulator, which drives a single ended primary induction controller. The digital signal processor processes and compares signals received from the sensors to calculate a depth of a buried conductor. The self-generated noise of the power supply unit does not interfere with the frequency bands of detection of the detector.