Navigation light monitor
 

I am trying to devise a simple circuit to monitor when a 24v nav lamp
has blown. Found this http://www.gammatron.com.au/datashee...0Datasheet.pdf
but at AU$54 it is pretty pricey. Should not be to difficult to make
up, but I need to know he values of the components. I already have
the switch, LED and a resistor to monitor when lamp is on.
TVMIA.

Navigation light monitor
 

CS wrote in
:

I am trying to devise a simple circuit to monitor when a 24v nav lamp
has blown. Found this
http://www.gammatron.com.au/datashee...0Datasheet.pdf but at
AU$54 it is pretty pricey. Should not be to difficult to make up, but
I need to know he values of the components. I already have the
switch, LED and a resistor to monitor when lamp is on. TVMIA.


Instead of putting the LED/resistor ACROSS the bulb, let's install a
little shunt in SERIES with the hot lead to the bulb that will rob 3
volts from the bulb's voltage when it's operating. We'll then use the
LED and a smaller current limit resistor in series with the LED to
protect the LED from overcurrent if the bulb shorts. INstead of the LED
operating on voltage provided by the switch, the LED will now light ONLY
if there is CURRENT going through a GOOD bulb, remaining dark if the
bulb blows....which it will do LOTS less operating from 21V, not 24V, at
only a tiny difference in brightness. If you're worried about the
voltage, notice how the CHARGING voltage is 28V when the engine is
running, which is what's blowing the bulbs in the first place.

switched shunt
+24VDC----|-/\/\/\/\/\--|-----to light
| |
|-LED--22ohms-|
A K

A=anode
K=cathode

Measure the current the bulb draws by leaving the switch OFF and putting
an ammeter (VOM on 10A scale) across the open switch terminals which
will make the bulb current go through the ammeter. Use the formula:

Ohms = 3V divided by AMPS to figure out the value of the shunt.

Use the formula AMPS X 3 VOLTS = WATTS to find out how many watts the
resistor gets then use a resistor spec that's about double what you
calculate.

The only way for the LED to light, now is when the lamp draws current
through the shunt, not just because there's voltage to ground. The
brightness of the LED is adjusted by varying the value of the 22 ohm
series resistor. You could easily make that a 100 ohm variable resistor
so you can set it like you like to see it. Use any 100 ohm thumbwheel
pot and set the pot to maximum resistance. Then, the first time you
light off the light with this circuit, just reduce the resistance to
increase the brightness but don't go to zero because 3V will destroy the
LED with overcurrent. If the LED gets warm, it's too much.

This circuit works on 12V too, but the bulbs never blow operating on 12V
(14.2V charging minus 3V shunt = 11.2V on 12V bulb.) We haven't
replaced a light bulb in years....

Sorry there's no fancy computer circuitry, LCD screen, big keyboard....
(c;]

Shhh....don't tell anyone, but his same circuit monitors the tower
lights blinking on the 2000' tower at the TV station to make sure it's
lit up so it doesn't attract airplanes.

By the way, the current through the LED is only about 20-80 milliamps
and you cna use the tiniest wire you got to remotely mount the LED far
away from the shunt, which needs to be right were the light's wiring is
now. Our LED panel is over the hatch to the forward compartment and
head so you can easily notice it every time you have to pee, which is
quite often, considering our beer consumption...(c;]

Navigation light monitor
 

CS wrote:
I am trying to devise a simple circuit to monitor when a 24v nav lamp
has blown. Found this http://www.gammatron.com.au/datashee...0Datasheet.pdf
but at AU$54 it is pretty pricey. Should not be to difficult to make
up, but I need to know he values of the components. I already have
the switch, LED and a resistor to monitor when lamp is on.
TVMIA.
Put the monitor led in series with the lamp, with two or tree
normal diodes accross the led to limit the voltage/current.
20 ohm resistor in series with the led is a good idea.
The shunt diodes must be able to carry the lamp current.
The read leds need the least voltage.

Navigation light monitor
 

Larry wrote in news:Xns9B5E990567CE2noonehomecom@
74.209.131.13:


switched shunt
+24VDC----|-/\/\/\/\/\--|-----to light
| |
|-LED--22ohms-|
A K

A=anode
K=cathode

M

The LED in series with 22 ohms across the shunt looked queer when I
downloaded it.

Navigation light monitor
 

On Nov 22, 9:04*pm, Sjouke Burry
wrote:
CS wrote:
I am trying to devise a simple circuit to monitor when a 24v nav lamp
has blown. *Found thishttp://www.gammatron.com.au/datasheets/GM050%20Datasheet.pdf
but at AU$54 it is pretty pricey. *Should not be to difficult to make
up, but I need to know he values of the components. * I already have
the switch, LED and a resistor to monitor when lamp is on.
TVMIA.

Put the monitor led in series with the lamp, with two or tree
normal diodes accross the led to limit the voltage/current.
20 ohm resistor in series with the led is a good idea.
The shunt diodes must be able to carry the lamp current.
The read leds need the least voltage.

Just put a cheap amp meter in series after the switch. When the switch
is closed and
you have current flow to the light the meter will show amps when bulb
opens or burns out the amp meter will show 0 amps.

Navigation light monitor
 

CS wrote:
I am trying to devise a simple circuit to monitor when a 24v nav lamp
has blown. Found this http://www.gammatron.com.au/datashee...0Datasheet.pdf
but at AU$54 it is pretty pricey. Should not be to difficult to make
up, but I need to know he values of the components. I already have
the switch, LED and a resistor to monitor when lamp is on.
TVMIA.

Sorry to dissent with most of you, but the original circuit makes much
more sense than anything else you propose. Someone with little
experience and desire to do some trials may be able to replicate it at
home with probably far less than U$D 10. The switch is the most costly
item of the assembly and the power diode follows.
Regarding the specifications of the components, they are not critical.
1) the diode must be any silicon diode able to sustain the power given
by the several amps of the lamp times 0.6V voltage drop.
2) The transistor can be any low power low frequency (low cost) PNP and,
3) for the resistors I would just start trying something like: R1 50-100
Ohm and R2 10 kOhm.
Some easy computation of the resistors could be done in advance but... I
am rather lazy and prefer trials and errors!
Daniel

Navigation light monitor
 

On 23 Nov, 12:23, Daniele Fua wrote:
CS wrote:
I am trying to devise a simple circuit to monitor when a 24v nav lamp
has blown. *Found thishttp://www.gammatron.com.au/datasheets/GM050%20Datasheet.pdf
but at AU$54 it is pretty pricey. *Should not be to difficult to make
up, but I need to know he values of the components. * I already have
the switch, LED and a resistor to monitor when lamp is on.
TVMIA.

Sorry to dissent with most of you, but the original circuit makes much
more sense than anything else you propose. Someone with little
experience and desire to do some trials may be able to replicate it at
home with probably far less than U$D 10. The switch is the most costly
item of the assembly and the power diode follows.
Regarding the specifications of the components, they are not critical.
1) the diode must be any silicon diode able to sustain the power given
by the several amps of the lamp times 0.6V voltage drop.
2) The transistor can be any low power low frequency (low cost) PNP and,
3) for the resistors I would just start trying something like: R1 50-100
Ohm and R2 10 kOhm.
Some easy computation of the resistors could be done in advance but... I
am rather lazy and prefer trials and errors!
Daniel

Thanks. I should add that the bulbs are 24v 25w so 1.04A.

Navigation light monitor
 

CS wrote:
Thanks. I should add that the bulbs are 24v 25w so 1.04A.

That's even better: if you will use your device only for 24V, the diode
needs to dissipate just 0.6W. Find a diode good for at least 3 times
this number and you are on the safe side. Just notice that the heat
(not large but neither totally negligible) will have to be removed and
redirected where it does not make any harm.

Daniel

Navigation light monitor
 

"Daniele Fua" wrote in message
...
CS wrote:
I am trying to devise a simple circuit to monitor when a 24v nav lamp
has blown. Found this
http://www.gammatron.com.au/datashee...0Datasheet.pdf
but at AU$54 it is pretty pricey. Should not be to difficult to make
up, but I need to know he values of the components. I already have
the switch, LED and a resistor to monitor when lamp is on.
TVMIA.

Sorry to dissent with most of you, but the original circuit makes much
more sense than anything else you propose.

Agreed. But it can be made even simpler: buy a cheap $2 current relay and
connect the coil in series with the lamp or even cheaper: buy a $0.10 read
contact and coil the wire to the lamp 20 times around the reed contact. The
contact closes when current flows through the wire. Drive a small lamp or
LED with it and you're done. And for the life of me, I cannot understand why
this is not a standard feature in ANY safety related application like nav
lights or even tail/break lights on cars...

Meindert

Navigation light monitor
 

Meindert Sprang wrote:
Agreed. But it can be made even simpler: buy a cheap $2 current relay and
connect the coil in series with the lamp or even cheaper: buy a $0.10 read
contact and coil the wire to the lamp 20 times around the reed contact. The
contact closes when current flows through the wire. Drive a small lamp or
LED with it and you're done. And for the life of me, I cannot understand why
this is not a standard feature in ANY safety related application like nav
lights or even tail/break lights on cars...

Meindert


Great! The reed contact idea sounds perfect. The only problem might be
mechanical if the cable is thick but, in that case, I guess you only
need few coils. It is a matter of finding just the minimum number of
coils to reach the threshold B considering Ampere law.

I will try it.

Daniele

Navigation light monitor
 

There are a number of monitoring applications in Safety Instrumentation
where you want to check for a fault on a circuit. Also a lot of cars
monitor lights and doors now.

To clarify the design criteria..
The circuit can be designed to indicate if a remote light is active.
But.. The circuit can also be designed to check for open circuit when a
remote light is inactive.

Take a fire alarm for example

_____________________________________________ ______________________
MonitorCCT
| | |
Supply
| Fire detector ( NO) | | End of Line Resistor
________________________________________________|_ ________________________|


The circuit is designed to monitor for open circuit ( No current through
monitor cct )
Fire -Maximum current through Monitor CCT.

There are also more sophisticated circuits that monitor each detector

Typical fire monitor cards in industry would be £300 each ..


To check a series bulb arrangement, a small current from a low voltage
source can be passed through the bulb when inactive and monitored to check
if there is continuity through the filament. So similar principle to the
fire detector. If no current at all there is a break in the circuit (
filament or wiring problem) small current, circuit ok but bulb not lit.
Apply a higher voltage, and you have a high current circuit and bulb is lit
ok .

The monitor circuit could be based on a couple of the GM050 circuits with
different supply voltages or something more sophisticated with a PIC to
complete the logic and operate the fault relays.

Is this a gap in the market???
Major opportunity here to make a million!.. out of yotties?? I won't order
the new car yet!

Regards

Bob
Simply Blue Too
Clyde

"CS" wrote in message
...
I am trying to devise a simple circuit to monitor when a 24v nav lamp
has blown. Found this
http://www.gammatron.com.au/datashee...0Datasheet.pdf
but at AU$54 it is pretty pricey. Should not be to difficult to make
up, but I need to know he values of the components. I already have
the switch, LED and a resistor to monitor when lamp is on.
TVMIA.

Navigation light monitor
 

Don't use DIGI modes on board Len but PSK at home using the soundcard and a
TS50 are easy.

Software like Mix32 and JVCOMM allow a variety of modes including WEFAX

As Larry says 10w is all you need for PSK, but you won't get BBS/EMAIL
unless you use PACTOR or Packet to hook up with your HAM BBS's. Are you
using PACTOR2 on board with a commercial supplier such as sailmail or
hooking up with a HF Amateur PACTOR BBS?
I used a KAM for PACTOR in the 90's but the soundcard does it all these
days.

Regards

Bob
GM4CAQ
Simply Blue Too
Clyde

"CS" wrote in message
...
I am trying to devise a simple circuit to monitor when a 24v nav lamp
has blown. Found this
http://www.gammatron.com.au/datashee...0Datasheet.pdf
but at AU$54 it is pretty pricey. Should not be to difficult to make
up, but I need to know he values of the components. I already have
the switch, LED and a resistor to monitor when lamp is on.
TVMIA.

Navigation light monitor
 

On Mon, 24 Nov 2008 09:04:38 +0100, "Meindert Sprang"
wrote:

I cannot understand why
this is not a standard feature in ANY safety related application like nav
lights or even tail/break lights on cars...

At one time Corvettes had optical fibers leading from the headlights
and so one to the instrument panel.

Casady