BF961 datasheet specifications

BF961 is a N–Channel Dual Gate MOS-Fieldeffect Tetrode, Depletion Mode.
BF961 Applications:
Input- and mixer stages especially for FM- and VHF TV-tuners up to 300 MHz.
Features:
 Integrated gate protection diodes
 High cross modulation performance
 Low noise figure
 High AGC-range
 Low feedback capacitance
 Low input capacitance
BF961 datasheet

One transistor audio mixer

one-transistor-mixerThe simpliest audio mixer schematic on the net. It has only one transistor and can support as many audio signal as you can afford. BC109C is a very cheap transistor and with a few resistor and capacitors you can build quickly a simple audio mixer that you can use in your pirate radio or wherever you want, imagination is the final frontier. Please keep in mind not to use higher voltages than 22V as a power supply for this audio mixer.

Stereo encoder High Separation

A higher channel separation stereo encoder built with 3 iC’s 4066, 4047, 4013 and 741. It has a filter L, C5 for frequencies higher than 15kHz and an extra audio amplifier built with 741. This stereo coder has a better design than this stereo circuit encoder but the principles are the same.
Stereo Encoder schematic components:
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