Hardware/Parallelport/heb microphone

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(Setup)
(Setup)
Line 26: Line 26:
 
The microphone's output is quite small.
 
The microphone's output is quite small.
 
It is first fed to a fixed amplifier through a passive RC highpass.
 
It is first fed to a fixed amplifier through a passive RC highpass.
The highpass has a cutoff frequency of ... Hz.
+
 
The amplifier has a gain of xxx.
+
The buzzer/microphone couple have 2 resonant frequencies: one at 3 kHz and the other at 4 kHz.
  
 
The trigger is a [https://en.wikipedia.org/wiki/Schmitt_trigger Schmitt trigger].
 
The trigger is a [https://en.wikipedia.org/wiki/Schmitt_trigger Schmitt trigger].

Revision as of 14:02, 18 May 2018

Contents

The board was designed for the SEm VHDL FSM lab.

It has a beeper which can emit a Morse code signal and a microphone for receiving it.

Version Photo Schematics Stock
V1.1 HEB-microphone HEB-microphone Schematic PDF 10 fully mounted

Beeper

The beeper is driven directly by a digital I/O line.

Microphone

The microphone's output is amplified and connected to an ADC. The amplified signal is also triggered in order to deliver a simple digital input to the FPGA.

Setup

The microphone's output is quite small. It is first fed to a fixed amplifier through a passive RC highpass.

The buzzer/microphone couple have 2 resonant frequencies: one at 3 kHz and the other at 4 kHz.

The trigger is a Schmitt trigger. When there is no signal, the trigger output can be as well low or high.

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