Gear LED cirquit (electronic specialists .. little help...

[Guest PoRrEkE]

Quick explanation.I study for Designer (idnustrial product) and our first assignment in dedicated fysics is to do something with LED's. The assignments we could chose from were waaaaay to easy I believe so I chose to invent my own (as was allowed).To combine both education with my sim I chose to try to create something usefull for the sim.The idea is to build a cirquit on 12V (PC power sup) which will light 4 LEDs as in the Fokker50 cockpit. 1 is blue and is mounted into the gear lever. 3 are green and are .. well y'all know these green ones.I have no experiance designing any cirquitry so if what I came up with so fare is anything good, I'll be amazed :)The idea is to use a push button as well as a relais (so that I have both a button and a switch). Then there are 3 timers (NE555 IC's), a set of OR ports (CD4071) and a set of NAND ports (CD4011) used as NOT ports.I made this cirquit based on what I read from datasheets and a few examples found on the web.If anyone can help me out here, that would be super :)2 things I need:1) is this cirquit correct ? what needs to be changed ?2) how the hell do I calculate the R's and the C's ?http://users.skynet.be/plipke/Schema2.GIF

[Guest PoRrEkE]

To give just a little more info:The system should work such that when the relais is opened the green leds are on. (meaning the plane is with gear down). When the button is pressed the timers start; turning on the blue led. Also the relais is closed turning off the green LEDs instantly.After the timer stops the blue led is turned off. (the gear is up).Now we push the button again. The timer starts again; turning on the blue led. The relais is opened again. This time only the timers keep the signal at the exit of the OR high and thus the green leds dark. Once the timers stop (at different times) the both inputs to the OR are low, thus turning on the green leds.The idea is to get 6, 7 and 8 seconds time delay by the timers. With the 8 seconds for the blue led and 1 of the green ones.

[Guest jan737]

If you use fsbus,why don't make it in CCC?I don't know how yet, but I think it's possible.Jan.

[Guest Erups]

I think the thing above can't do what you want.As far as i know the 555 can work as an oscillator, pulse generator, pwm generator, and that kind.But not as a counter.You need a counter for your thing to work.Example:you have an oscillator generating 5 pulses per second, then 3 counters.Each of these counters are configured to count a number of pulses before putting their output to high.First problem is this.Second is the transistor and the reset of the counters:the button is momentary i assume (not maintaining the position).If so, you need something that with each pulse of your button changes and maintains its state (don't remember its name :().In my opinion you need two of these.Gonna make a block schematic for you, wait :)

[Guest Erups]

>If so, you need something that with each pulse of your button>changes and maintains its state (don't remember its name :().It's called FLIP-FLOPAt a pulse on the input, it changes state of the output between logic HIGH and logic LOW.Here is my scheme:http://forums.avsim.net/user_files/94358.gifExplanation:the oscillator is always active, generating that many pulses per second.The counters cannot count as long as the reset input is high.The button makes the FLIP-FLOP change state.The state of the FLIP-FLOP drives both the counters' reset input and the blue led (no need for a relais-rel

[Guest Erups]

When exactly should the blue led light up?Both on lowering and on rising the gear?Or only one of the two?Which one?

[Guest PoRrEkE]

Folks folks ... read some 'bout the 555 first then :(Inside the 555 there is a flipflop and the 555 can both be used astable (oscillator / timer) or monostable (delayer / single puls generator)And using FSbus ... first I have no FSbus, second that would be easy again and not sutable for my school project.

[Guest PoRrEkE]

http://technologystudent.com/elec1/5554.htmcheck this page for more info on the 555 used monostable.

[Guest PoRrEkE]

Both.During any gear-travel .. the blue led is on inside the rounded transparent knob on the gear lever.The green leds only go on when gear is detected fully down.

[Guest Erups]

I need a more torough datasheet for the 555, the one i have is not very complete :(Do you have one?

[Guest PoRrEkE]

I have 2.One from Philips and one from another brand.Lets see:www.datasheetcatalog.comThere if you type to search for "NE555", you'll find some.I noticed 1 more issue in my cirquit. I use a relais but that's not the correct component.What I need is this:push button: 00100000000000000000000000000010000000000000000000000component..: 00111111111111111111111111111100000000000000000000000So that it seems as though there is both a push button in my system as well as a switch.

[Guest Erups]

>push button:>00100000000000000000000000000010000000000000000000000>component..:>00111111111111111111111111111100000000000000000000000I think this is exactly a flipflop?I found the monostable operation, with which you pretty much solve the blue led problem.But there is no mention of counting abilities :(Monostable, astable, frequency dividing, pwm generation and ppm generation.I'll look for something else.Anyway assuming you have the counters doing the work for the green lights, this is my solution for the blue led:two monostable, two NOT port and an OR port.Assuming there is still the flipflop.The NOT inverts the flipflop output and takes it to the trigger input of one of the monostables.This way, when you trigger your button, the flipflop flips, the not port inverts and you have a high pulse on the corresponding monostable.The second monostable has also its trigger inverted by the other NOT port, but the trigger signal comes from the output of one (or more using AND ports) of the green light counters: when the green light goes out, the inverted signal on the trigger input is high, and the monostable starts.And OR port on the two outputs of the two monostables, ensure continous operation of the LED.

[Guest PoRrEkE]

> I found the monostable operation, with which you pretty much solve> the blue led problem.> But there is no mention of counting abilities :(That's the point .. it is a timer, not a counter.When used monostable it will give 1 output pulse (with variable length in time) on each short input pulse.E.g. wire a buzzer to a push button: the busser wil buzz as long as you press the button.Now wire a (monostable wired) 555 between them. If you press the push button short, the buzzer will buzz for a time (according to the resistor and condensator value).If you wire it to an astable 555 the buzzer will go on/off/on/off like an allarm for as long as you do not reset the 555 (i think). That's how you can make a counter out of a 555. It will not count but it will generate a lasting block-wave.

[Guest Erups]

Then you simply use a 555 to generate a pulse train, and three counters as in my first scheme.The things i said for the blue led should apply.

[Guest PoRrEkE]

a puls train ?you mean i should use the 555 as a continuous puls generator and then use a counter to count the pulses ??why ??!!if I can make the 555 to output a singal that lasts 6 seconds, than that is just right for the green led !if I can make an other 555 to output a signal that lasts 8 seconds, that is just right of the green and blue led !I don't think I need no counter if I use the 555 monostable!