Administrators Andres Ramos Posted April 8, 2022 Administrators Share Posted April 8, 2022 Introduction This development actually was a spin-off from an experiment with light coming from the sky that can be found here. In this experiment I observed that daylight shining on a phototransistor with a substantial light intensity causes noise that shows pk modulation. During my experiment I tested light sources different from daylight and found out that ultraviolet and yellow LED light are causing more or less the same effect. That opened the path to a device I called LINGER (Light Induced Noise Gated EVP Receiver) Schematic of electronic circuit As you can see the electronic is rather simple. The first stage is made of the transistor K2 that drives the LED to excite the phototransistor K3. The LED light can also be modulated by an external audio source through the connector X1. Transistor K4 is a tricky feature that is boosting the output of the noise from K3. The transistor K5 is levelling the amplitude up so that the final stage made from the SSM 2167 can work with it properly. This circuit is a microphone signal conditioner. It amplifies and compresses the signal and routes it through a noise gate. The noise gate works as a very effective amplifier for pk modulation. What makes working with this device so appealing is the fact that you only need one knob to adjust the pk modulation for maximum and a second knob to adjust the external modulation. However you also can run the LINGER without modulation. The device is powered by 8 NiMH batteries. 0 Quote Link to comment Share on other sites More sharing options...
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