We found this filter in a documentation for radio amateurs from 1974. The transistors could be the BC558 and if the power is inverted we can use the BC548. The capacitors determine the range and can be changed in a good range of values.
We found this filter in a documentation for radio amateurs from 1974. The transistors could be the BC558 and if the power is inverted we can use the BC548. The capacitors determine the range and can be changed in a good range of values.