Faulty-Lamp Indicator

[carbee]

design a faulty-lamp indicator that monitors 64 lamps at the end of an airport runway. When the lamp is operating, the voltage at that lamp’s terminal is 5 V. When the lamp is faulty, the voltage is zero. The output of the indicator must have two 7-segment LEDs that indicate the number of the lamp being tested (0 to 63). If a fault is detected, a single LED must light to indicate that the lamp at this number position is faulty.

i badly need a simple idea on how to design this using flip flops and logic gates. thanks

 

[anboli]

you just need to found out faulty lamp thats all know,,

then you go with Current Transformer to read the load of the output...
**broken link removed**

 

[betwixt]

I'm not sure a current transformer is the correct device for this application. You need to know whether the lamps are AC or DC powered, I'm guessng this is a hypothetical situation and DC is used, a real runway wouldn't use 5V lamps!

You have to make a decision about how much wiring can be used. The simplest solution I can think of without using a microcontroller is to run seven signal wires around the lamps (assuming ground and +5V are already available at each lamp position) six of the wires carry a binary address (0 - 63) and the seventh carries the good/bad indcation. At each lamp, decode it's address from the wires and gate the lamp voltage on to the indicator wire. Back at the control box, use a counter to generate the addresses in sequence, put the address on the wires and also to the LED counter and connect the indicator wire to the 'Fail' LED.

Brian.

 

[chuckey]

Given that you have 0 and +5V at each "lamp", the question is of how many conductors you have to run around your airfield (miles of cable?), is not trivial, also its configuration, can you loop from lamp to lamp or are they star wired? Can you rely on the lamps 5V for your telemetry, cos' if that goes, the lamp goes out and there is no volts for the telemetry!
One stand alone solution might be to feed the telemetry for the lamps all from a +12V supply. this supply is cut say for 10mS every second. So at every lamp position, there is a RC filter feeding a 5V regulator, so that you now have an independent telemetry 5V supply at each lamp. At each lamp position, if the lamp is fault, the local logic puts a short on the 12V feed for say 1mS at its specified time slot.
So at the 12V PSU end, you monitor the out going line and decode which lamp slot is taking the current (output voltage falls).
Frank

 

[carbee]

it is really just a situational analysis given certain conditions:
thanks brian, but the only problem is the components needed to be used are the following

IC Number Quantity
74LS92 2
74LS90 2
74LS161 2
74LS160 2
74LS47 2
74LS151 1
555 Timer 1
330ohm DIL resistor module 2
1 k ohm 2
2 k ohm 1
Trimmer pot 1M ohm 1
1N914 diode 1
0.001 microFarad 1
0.1 microFarad 1
0.22microFarad 1
7-segment LED Display (common anode) 2
LED (red) 1

 

[betwixt]

I can't see any way of monitoring 64 different sources with only those components, however they are suitable for the control box alone (excluding circuits at the lights). I have been trying to visualize a way of sending the data serially and I wouldn't exclude it's possibility but those certainly wouldn't be my choice of components to do it. The 555 must be used as a clock generator with at least one of the capacitors, one fixed resistor and the trimmer pot. The 74LS47s must be used to decode and drive the signals to the two LEDs and I would guess the DIL resistors are in series with the LED segements. I can't see how the remaining counters and gates can be used to read back 64 different inputs without some extra parts at the lights end of the connection.

Brian.