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G8MNY > TECH 06.04.20 09:00z 109 Lines 3619 Bytes #999 (0) @ WW
BID : 51121_GB7CIP
Read: GUEST
Subj: Toggle PTT
Path: HB9ON<IW8PGT<IZ3LSV<IR1UAW<I0OJJ<GB7CIP
Sent: 200406/0855Z @:GB7CIP.#32.GBR.EURO #:51121 [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)ÄÄÄÂÄÁÄ´/' 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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