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#1
posted to rec.boats.electronics
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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 |
#2
posted to rec.boats.electronics
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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. |
#3
posted to rec.boats.electronics
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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 |
#4
posted to rec.boats.electronics
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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 |
#5
posted to rec.boats.electronics
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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 |
#6
posted to rec.boats.electronics
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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 |
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