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.