Here is the European to US Trailer converter 3 => 2 w/o =
voltage drop
caused by diodes. I have designed this for my own purposes. =
This
could be the same schema Mike mentioned.
You need:
2 pcs =
change over
relays (12 V automotive or general)
2 pcs 1 Amp diodes
2 pcs =
electrolytic
capasitors
some wire, connectors etc.
And it works as
follows:
If the ST wire has + 12 V then both LTS/ST and RTS/ST =
has + 12
V.
If LTS has + 12 V then its relay is energized and connects it to
LTS/ST.
If both ST and LTS wires have + 12 V then LTS is =
dominating.
While
LTS flashes + 12 V on/off capasitor keeps relay energized during
off =
-periods
=> same tact and flashing rate as in towing =
vehicle.
Selecting
capasitor value (voltage rating 25 V preferred):
First measure =
impedance
of your relay.
If you have automotive relay its impedance might be =
100 to 150
ohms and general relays could be 200 to 300 ohms.
100 ohms =
=> 3300
mikrofarads
150 ohms => 2200 mikrofarads
300 ohms => =
1000
mikrofarads
These values give about 500 ms off delay to
relay.
Schema:
Diode:
(anode)--D|--(cathode)
Capasitor:
__|__ +
terminal
|____|
=
-------
| - terminal
Relay
coil:
=
__|__
|__\__|
|
Poles of the relay
(drawn as de-energized)
n/o
---o
 =
;
/o--- c
n/c ---o/
GND = GROUND
TL = TAIL =
LIGHTS
LTS =
LEFT TURN SIGNAL
ST = STOP or BRAKE LIGHTS
RTS = RIGHT =
TURN
SIGNAL
GND =
---+--------------------(white)------------------------
GND
=
| TL =
-----------(brown)-----------------------
TL
&=
nbsp;
|
&n=
bsp;
| LTS
---+-------------------------------o
&nb=
sp;
| =
| =
&=
nbsp; &n=
bsp;
/o---
LTS/ST
&nb=
sp;
| =
+--D|---+-------------+
o/
&=
nbsp;
| =
__|__ =
__|__
|
&n=
bsp;
| =
|____| |__\__|
|
&n=
bsp;
| =
=
------- =
|
|
&n=
bsp;
| =
&=
nbsp;
| =
|
|
&n=
bsp;
+---------------------+-------------+ =
|
&n=
bsp;
| ST
---(red)---------------------------+
&nb=
sp;
+---------------------+-------------+ =
|
&n=
bsp; &nb=
sp; &nbs=
p;
__|__
__|__
|
&n=
bsp; &nb=
sp; &nbs=
p;
--------
|__\__|
|
&n=
bsp; &nb=
sp; &nbs=
p;
|____| =
|
|
&n=
bsp; &nb=
sp; &nbs=
p;
| =
|
|
&n=
bsp; &nb=
sp;
+--D|---+-------------+
o\
&=
nbsp; &n=
bsp;
| =
&=
nbsp; &n=
bsp;
\o---
RTS/ST
&nb=
sp;
RTS ---+-------(green)--------------o
Hope this will help
someone.
Juha Koivisto
88 Vanagon (Caravelle) 1,6TD (old =
school bus
with 9 seats)
TURKU, FINLAND