VOX printed circuit board

9-22 — elektor september 1980 VOX printed circuit board VOX printed circuit board particular voice pattern, since both the bandwidth and the centre frequency are adjustable (with P2 and P3 respectively). The two other potentiometers are to preset the input sensitivity (P1) and the length of the delay (P4). In practice, the range of P1 should be adequate since the gain of the microphone preamp Al can go up to 100 X. Delay time however can be a matter of personal preference. With the values of P4, R20 and C7 as given in figure 1 the delay time is adjustable between 0.5 and 2.5 seconds. The range can be altered by changing the values of any or all of these components. The layout of the printed circuit board for the VOX is shown in figure 2. Everything in figure 1 is included on the board with the exception of the two stereo potentiometers, the relay and the microphone. For a more precise description of the VOX circuit readers are referred to the previous article published in Elekto...