G8MNY  > TECH     24.06.21 09:00z 109 Lines 3617 Bytes #169 (0) @ WW
BID : 38886_GB7CIP
Subj: Toggle PTT
Path: ED1ZAC<ED1ZAC<CX2SA<EA2RCF<I0OJJ<GB7CIP
Sent: 210624/0820Z @:GB7CIP.#32.GBR.EURO #:38886 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To  : TECH@WW

From: PA3BNX@PI8SHB.#NBO.NLD.EU                   (New Apr 06)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)

Hello All,
Subject: Handsfree ptt-switch for mobile use.
---------------------------------------------------
Using a vox is not nice in a car because it goes transmitting when it hears
sounds.

Keeping a ptt switch pressed while driving & stearing is also unsafe.

Thats why I decided to make a large toggle switch on the dashboard with a Red
5mm flashing PTT led & a Mic gain control.

Construction of toggle switch
-----------------------------
I made from double clad PCB about 3 x 6 cm & a microswitch as a nice toggle
switch. I did solder a small hange to the PCB& tinned box. And I mounted the
microswitch in the metalbox & only the handle pin is pushed when the PCB piece
is pushed. I did painted it red hi.
So I have a nice big easy to push PTT switch.

Circuit diagram
---------------
I have made a small metalbox with a large pushbutton (S1) on it.
And a big bright 5mm led.
The pushbutton is connected to a toggle circuit.
The output of the toggle circuit is connected to a watchdog circuit which
drives a PTT transistor to switch the tranciever, & also the LED flasher
circuit.
Use a 5 mm highbright led so you see it very easy flashing when transmitting
without having to look at the tranciever.

So push S1 & PTT is on for maximal 3-5 minutes & the led flashes. After 3-5
minutes the watchdog switches off the mobileset from transmitting.
(use 100-220uF).

So if something happens your rig is not any more transmitting a carrier for
hours.

Mount the small box some where on the dashboard next to the steering wheel so
you can easy see the led & push the S1 Switch.

Further I mounted a small electreet at the sunscreen for getting the sound.

I also mounted a small mic-preamp with a gain potentiometer in the
ptt switchbox so I can adjust the audio level when driving.

PTT toggleswitch
----------------
100nÚÄÄÄÄÂÄÄÄÄÄ1MÄÄ¿
   ===   ³S1       ³ 10106 or 4093 etc.
    ³    o         ³
 ÚÄÄ´    \  ³\     ³  ³\
_³_ ³1n  ÃÄÄ´ `>oÄÄÁÄÄ´ `>oÄÄÂÄÄÄÄ>to A
   ===   ³  ³/'       ³/'    ³
    ÀÄÄÄÄÁÄÄÄÄÄ100kÄÄÄÄÄÄÄÄÄÄÙ

Watchdog & led flasher
----------------------
                ÚÄÄÄÂÄÄÄÄÄÄÄÄ +Vcc 9Ä15V
                ³   ³
A              3M3 _³_ 1N4148
³               ³  /_\                    ÚÄÄÄÂÄÄÄÄo Ptt
³  _            ³   ³    _ 4093     BC547 ³   ³
ÃÄ´ `\     100u ³   ³ ÚÄ´ `\            ³/   _³_
³ ³ & )oÄ1kÄÄ´ÃÄÁÄÄÄÁÄ´ ³ & )oÄÂÄ10kÄÂÄij    /_\
ÀÄ´_,/         +      ÀÄ´_,/'  ³     ³  ³\ e  ³ 1N4007
    4093                       ³    4k7   ³   ³
 GroundÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ)ÄÄÄÄÄÁÄÄÄÄÁÄÄÄÁÄÄÄÄo
                               ³
 ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ
 ³   _
 ÀÄÄ´ `\      _ 4093
    ³ & )oÄÄÄ´ `\
 ÚÄÄ´_,/     ³ & )oÄÂÄÄÄ1kÄÄÄ¿
 ³         ÚÄ´_,/   ³+      _³_
1M        100k     === 1uF  \_/ð Red 5mm Led.
 ÀÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÙ        ÁÄÄÄÄÄÄÄGround

MicÄampliflier
--------------
2 wire electret.
     ÚÄÄÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÂÄÄ560ÄÄ+Vcc 9Ä15V
     ³        ³                  10uF ³+
    4k7      22k                     ===
     ³        ³   741 or LF353       _³_
     ³        ÃÄÄÄÄÄÂÄ´\     + 10uF
     ³ u1     ³100p===³ñ`>oÄÂÄ´ÃÄ¿
³()ÄÂÁÄ´ÃÄ4k7Ä)ÄÄÄÄÄ´/'   ³    ³
 ³ ===    +ÚÄÄ´   ³         ³   5k
 ³  ³1nF  === ³   ÀÄ47kÄÄÄÄÄÙ   pot<ÄÄo Rig Mic
 ³  ³   10u³ 22k                 ³
 ÀÄÄÁÄÄÄÄÄÄÁÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄo

Gain = about 10x

I did not wrote the pin numbers of the ic's to it yet.

73's from PA3BNX@PI8SHB.


Y don't U send an interesting bul?

73 de G8MNY @ GB7CIP


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