100 LED Display - Please help, my job depends on it!!

[ericgibbs]

Ok I have put together this circuit based on what ericgibbs has posted using a 74HTC164. It only includes the control circuit and the resistors for the LEDs. Each of the green pads will go to an LED. I have a couple of questions...

1) Have I done this right?!
2) What do I do with all the clock inputs?
3) Will this circuit definitely do what I need ie - count up by one everytime the button is pressed whilst keeping all the previous LEDs illuminated?
4) What power supply will I need if I am using 1.85V red LEDs with a 20mA operating current?

If I can't get this circuit sorted by the end of today I think I'm going to have to go down the dip switch route...

Thanks

Leo

At 20mA per led for 8 led's the specified current rating and dissipation of the 74HCT 164 will be exceeded.
A suitable shift register would be TPIC6595.

Compared to the bit switch solution the S/R will be expensive and lack memory retention at power off.

 

[blueroomelectronics]

It also can't decrement if you press the button too many times.

 

[MrDEB]

Thats exactly what I was thinking

too many presses and the "SB1 rocket" would act like Berni Madoff
If the op decides to go with the 74164, would my proposal of multiplexing using a 4017 be an option to limit the LED current?
Sometimes the trees get in the way of seeing the forest
I vote for the dip switches. Easy, cheap and the entire circuit could be crafted in 2 hours using all dip sockets.
Bargraph displays, dip switches, resistor arrays.
Heck the resistor arrays alone would save 90 solder connections. 200 (2 per resistor vers 11 per array)unless you go with 16 pin arrays (14 resistors per dip package)
The displays if not long enought, just double the number of displays.
each 20 led display is 50.7mm long x 5 =9.84 inches. If you want a 21inch display (2 LEDs per quota amount no big deal. The displays are end stackable.
Just need to speed up the multiplexing clock.
the op has 10 days left!!

 

[blueroomelectronics]

A 5V @ 1.2A switchmode wall supply is common and cheap. 100 LEDs at 10mA each is only 1A.

 

[MrDEB]

But how bright?

at 10 ma??
I like bright LEDs
lets try 50ma ---lol

 

[ericgibbs]

at 10 ma??
I like bright LEDs
lets try 50ma ---lol

hi,
The OP did say 20mA.

 

[blueroomelectronics]

Well then a 3A wall supply.

 

[MrDEB]

For life expectency = 15ma

sure 20 ma is the norm but 20% or so is perfered.
You car may go 100mph but do you ever run it to the max??
In my designs I shoot for 15-18ma max

 

[blueroomelectronics]

Modern LEDs are pretty bright with less current than older LEDs. Just get them with a high MCD rating.

 

[ericgibbs]

Well then a 3A wall supply.

Bill,
I would use 100 large red marbles in a end lit, clear plastic tube.
Drop in a marble as required.

Zero energy.

 

[blueroomelectronics]

Well the OP better get cracking with whatever design he plans to use. I like the marble idea but I suspect they would get pretty dim after it started filling up.

 

[MrDEB]

her are the specs for bargraph leds

DC20/20SRWA Super Bright Red (GaAlAs) WHITE DIFFUSED 8000 31000 20 Segments
Bargraph-Displa

 

[Boncuk]

You car may go 100mph but do you ever run it to the max??

Not a good question.

My last car (Ford Scorpio) had a max speed of 200km/h resulting in an 8 hour trip from Hamburg to Munich, which meant a bad ratio of travel time vs. work time. (very often a one or two hour job to do)

After tuning it made 280km/h ensuring a travel time of not more than 5 hours.

Only flying is faster.

Bonuk

 

[MrDEB]

yes I have heard of the Autobahun

supposly has the least traffic fatalities per mile than any other highway in the world
and an unlimited speed limit to boot
go figure.
but then I guess you never drove on a S. cal freeway
max speed is like 30 if your lucky.

 

[Boncuk]

but then I guess you never drove on a S. cal freeway
max speed is like 30 if your lucky.

I did too, felt like being able to pick flowers on the way.

BTW, speed limit in German cities is 50km/h. Going through Munich at 80km/h police still waves their hands to speed up.

 

[Mr RB]

Bill,
I would use 100 large red marbles in a end lit, clear plastic tube.
Drop in a marble as required.

Zero energy.

Wow! And I thought Bill's idea was minimalist genius.

Add a 5w bright red laser shining up from the bottom of the tube to make the marbles glow (and maybe a brightness adjust knob) and that would be a fully workable and visually beautiful display.

 

[MrDEB]

Add a pic controlled device

that drops a marble into the tube, makes the laser blink then an alarm sounds!!
sounds like a great idea
lets see you need a pic with software then a 2803 to drive the servo motor that controlls the elevator that gathers up a marble or more as needed then transports the marble/s up to the top of the "SB1" rocket and deposits them
the laser then blinks by way of a pic comand.
have a light sensing cell so at night when nobody is at work, the laser shuts off to save energy. Of coarse in the pic code you need to puyt the pic in sleep mode.
the op had better get cracking and maybe Bill will program the pic for the op
LOTS TO DO. only 8 days left.
sure hope parts have been ordered.
are you sure a 5W laser is big enought?
maybe program the pic to measure the weight of the marbles and switch on a second and/or third laser according to the weight/# of marbles
LOL

 

[blueroomelectronics]

And it's gotten complex again. K.I.S.S.

You're right MrDEB, I would have done it with a PIC & a 10x10 matrix for the LED wiring.

PS firing a laser through glass marbles is not a good idea. Unless you're building a blind-o-matic.

 

[MrDEB]

The op would have been better off

going the pic route.
would be a simple up count code with option to count down if need be.
actually the pic would have been easier maybe than the dip switches.
My question is why did the op start throwing 74164's into the mix?
going from A to B via C, D, and E. IMO
I really like the laser idea could be exciting

 

[MrDEB]

8 days left!!

WARNING WARNING
only 8 days until blast off of the SB1 rocket
wonder how its comming along
getting comcerned as we have no contact!!!