Open.Theremin.UP Schematic
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The Open.Theremin.Up is a micro controller board based on the ATTiny 416-20 (U6). This circuit measures basically the signals from two open.theremin.lc circuits and generates a synthetically generated sound from it. Using a simple calculation the linearity of the theremin is improved. By using a look up table any sound wave form can be generated. The micro controller is clocked by the quartz oscillator from the lc-circuit connected to K1. The 16 MHz signal can be measured at point V1 (see schematic). The signals for the open.theremin.lc are measured with a sampling frequency of 31.25 kHz. This sampling frequency can be found at V2.
V1: Deduced 16 Mhz clock
V2: 31.25 kHz sampling frequency
The theremin signals coming from the two open.theremin.lc circuits connected to K1 and K2 are fed to the comparator circuit TL072 (U7). The hysteresis is precisely generated by the resistors R15 through R20. The comparator transforms the incoming triangular signal into a 5V pulse signal for the micro controller. The two pulse signals can be measured at V5 and V6.
V3, V4: Incoming triangular theremin signal and generated hysteresis
V5, V6: The comparator output signals fed to the micro controller
TP1 / TP2
TP3 uP Pin1
Audio Outupt Signal (generated from a look up table)
VCC
+5V