Message 26107 in TECH.WW
From: G8MNY
Date: Mon, 20 Jul 26 06:45:00 Z
Newsgroups: TECH.WW
Subject: Another Mic Preamp
Message-ID: <65341_GB7CIP>
Path: N2NOV|K7EK|DK0WUE|PI8LAP|GB7BED|GB7COW|GB7CIP
R:260720/0653z @:N2NOV.#RICH.NY.USA.NOAM $:65341_GB7CIP
R:260720/0652z @:K7EK.#NOKY.KY.USA.NOAM $:65341_GB7CIP
R:260720/0652Z 32622@DK0WUE.#BAY.DEU.EU LinBPQ6.0.25
R:260720/0652Z @:PI8LAP.#ZLD.NLD.EURO [Kortgene] #:9726 XrLin505c
R:260720/0652Z 14567@GB7BED.#21.GBR.EU LinBPQ6.0.25
R:260720/0648Z @:GB7COW.#44.GBR.EU #:44932 [Hartland] $:65341_GB7CIP
R:260720/0645Z @:GB7CIP.#32.GBR.EURO #:65341 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To : TECH@WW
From: 2E1ESY@GB7NND.#23.GBR.EU
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
The microphone below I have made & used now for around 15 years, it has lots of
gain & a very small current drain, the 1.5V battery will last for over a year
with daily use.
Pre-Amp Microphone
==================
+1.5V
Resistors:- R1,R4=1k. R2,R7=100k. R3=470ohm. R5=10k. R6=510ohm. RV1=5k lin pot.
Capacitors:- C1,C4,C7=1mf mini electrolytic capacitor. C2=1nf disc capacitor
C3,C5,C6=4.7nf disc capacitor.
Transistors:- T1=BC549C. T2=BC559C.
E1=Electret Mic Element. SW1=D.P.D.T. Switch.
---------------------------------------
MATRIX BOARD LAYOUT
===================
Output to TX >>>>
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
DIAGRAM VIEWED FROM COMPONENT SIDE, COPPER STRIP ON OPPOSITE SIDE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
e c
c e
+ = Marked on diagram for the positive connection on electrolytic capacitors
L=Link Wire. B1=1.5V AA Cell Battery
---------------------------------------------------------------------
Why don't U send an interesting bul?
73 De John, G8MNY @ GB7CIP
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