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G8MNY > TECH 11.09.08 00:07l 63 Lines 2390 Bytes #999 (0) @ WW
BID : 2467_GB7CIP
Read: GUEST
Subj: Towing & Reversing Beeper
Path: IZ3LSV<IK2XDE<DB0RES<ON0AR<GB7CIP
Sent: 080910/2138Z @:GB7CIP.#32.GBR.EU #:2467 [Caterham] $:2467_GB7CIP
From: G8MNY@GB7CIP.#32.GBR.EU
To : TECH@WW
By G8MNY (New Sep 08)
(8 Bit ASCII Graphics use code page 437 or 850)
Here is a circuit I used, originally based on a trailer indicator warning kit.
WHAT IT DOES
Normally it just beeps if there is a trailer lamp connected & an indicator is
powered (UK tow regulation). I modified the original unit to also beep as an
added safety feature, if I was reversing (with or without a trailer).
Flashing LED
///
Connection from ÄÄÂÄ´>ÃÄÄÂÄ´>ÃÄÄ¿
Reversing Light ³ +10u ³ D1 ³
ÀÄÄ´ÃÄÄÙ ³
³
ÚÄÄÄÄÄÄÄÄ´>ÃÄÄ´
\³ D2 ³
PNPÃÄÄÄ¿ ³
e/³ 100 ³
Connection from ³ ³ ³ Trailer
Flashing Right ÄÄÁÄ´>ÃÄÁÄÄÄÄÄÄÄ)ÄÄÄÄ> Pin 4
Indicator D3 ³ RHS Ind
³
ÚÄÄÄÄÄÄÄÄ´>ÃÄÄ´
\³ D4 ³
PNPÃÄÄÄ¿ ³
e/³ 100 ³
Connection from ³ ³ ³ Trailer
Flashing Left ÄÄÁÄ´>ÃÄÁÄÄÄÄÄÄÄ)ÄÄÄÄ> Pin 3
Indicator D5 ___³__ LHS Ind
³ Small³
³Buzzer³
~~~³~~~ Trailer
ÃÄÄÄÄ> Pin 1
_³_ Earth
HOW IT WORKS
The trailer lamps are powered via power diodes D3 & D5 (1N5401) & the voltage
drop across these turns on either of the 2 small PNP transistor to power the
small buzzer via a low power steering diode D2 or D4 diode (1N4001).
The additional reversing beeper uses a flashing LED in series with buzzer & a
diode to give the same effect, this time as public warning. The 10uF capacitor
is needed to stop the buzzer AC pulses affecting the LED internal timer.
The flashing LED is the smallest flasher unit of its size & I have made use if
it in several applications now.
LOCATION
This circuit is located at the rear, behind one of the lights clusters as it
needs to be connected to both indicators & a reversing light feed, & be
audible both in the driver & nearby pedestrians.
Also see Fred G4VVQ's TECH bul "Towing Scoket For Caravans" that I put out.
Why Don't U send an interesting bul?
73 De John, G8MNY @ GB7CIP
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