The Rangemaster was born at John E. Dallas & Sons in the 60's.
It is said that Eric Clapton would have used it on the famous album: "Blues Breakers with Eric Clapton" but nothing confirms it. On the other hand it can be said that artists such as Ritchie Blackmore, Brian May, Tony Iommi have largely made popular this type of effect.
Technically, there is an input filter that cuts off some of the bass, then the signal is amplified with a slight distortion by a single transistor, the OC44 (or the OC71).
The original is mounted in a box devoid of footswitch which is not very practical. Also, I decided to mount the circuit in a traditional effect box but wired as the original, in point to point.
The transistor was chosen to obtain a polarization similar to the original, a collector-mass voltage around the 7V.