This circuit enables the user to blend in one 5 separate signals from 5 dynamic low-impedance microphones and a couple of external auxiliary inputs, which can be electret-type microphones or even actually amplified inputs for example those from your CD player or a phone.
The circuit really is easy and is made up of feedback preamplifier stage, wherein input is positioned through a system of seven signals.
In the beginning I believed this circuit was intended to be for use in an outdoor system attached to a telephone mixture. Therefore several microphones and only a couple of auxiliaries were involved. Within the auxiliaries hook up a micro electret which usually adequately catches the background noise and in other signals, through a resistance of 100K in series which doesn’t show up in the diagram, hook up any convenient that enables to key in to the air Which can be faraway from where the system is positined. The overall performance of the circuit is extremely decent, because it simply needs 12V for its power could be provided from both a battery and a DC adapter source. The usage is incredibly low (around 10mA) and also the audio quality is extremely good. Naturally, being anything specifically within the phone had been developed in mono settings, however nothing at all inhibits you from mounting a couple of equivalent circuits with double potentiometers and create it into a full fledged stereo mic mixture circuit. Inside the microphone inputs you should make use of 6.5mm mono female plugs being that they are standard on lower Z microphones. The auxiliary inputs as an alternative tend to be freer. for me I used MiniDIN chips, such as the types used in the brand new PC’s mouse. These types of chips are extremely affordable and have a mechanised contact protection better than typical 3.5mm stereo. Utilizing three terminals on the auxiliary inputs, the signal input and the polarization voltage (BIAS) needed regarding a micro electret could be delivered through various routes. In case an amplified transmission is presented at the input, you should never hook up the polarized voltage please remember to put the resistance of 100K within the connector.