This simple general-purpose transistor mixer was taken from an article in Electronics Now magazine in March 1994. You can choose a low-noise transistor such as the BC549.
I found this circuit in a Popular Electronics from November 1999. The magazine is no longer...
This circuit of a 1991 PE Hobbyst Handbook allows the brightness of the incandescent lamp to be...
This simple operational amplifier tester was published in the November 1987 issue of Radio...