2 Tube contact microphone amplifier

2 Tube contact microphone amplifier

Published by: Julia

On: 25 Okt, 2018

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Category: Amplifier

2 Tube contact microphone amplifier Rating:
3.5
86 out of 100 based on 235 user ratings

This amplifier is a high gain unit suitable for increasing to headphone level sounds of very small amplitude. The contact microphone is a crystal or magnetic unit attached to an instrumanent sounding board, table or any other surface resonant to s...

This amplifier is a high gain unit suitable for increasing to headphone level sounds of very small amplitude. The contact microphone is a crystal or magnetic unit attached to an instrumanent sounding board, table or any other surface resonant to sound. just to name to uses for an instrument of this type, it could be used by a physician to detect malfunctions of the body or by police as a detecting device.


Battery power is used on this device for quitness and minature type tubes for compactness, making the whole portable. The microphone should not be placed over 10 feet from the amplifier and shielded microphone wire used if best results are to be obtined.


Parts List
C-1 .05 mfd 400v paper cond.
C-2 .01 mfd 400v paper cond.
C-3 .05 mfd 400v paper cond.
C-4 .01 mfd 400v paper cond.
R-1 10 meg. ohm 1/2 watt res.
R-2 1meg. ohm 1/2w res.
R-3 2 meg. ohm vol. con.
R-4 1 meg. ohm 1/2w res.
R-5 500,000 ohm 1/2w res.
R-6 1 meg. ohm 1/2w res.
"A" 1 1/2 v. dry cell
"B" 671/2 v. min. battery
M Crystal or mag. contact mic.
J Headphone jack sockets-2 min. 7 pin

Contact Microphone To Amplifier,

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