Help re-creating a replica movie prop

[betwixt]

It should be like this:

Thumbwheel 'common' goes to supply.
Thumbwheel 'outputs' go in parallel to the same data input pin across all 4511s at once. Each of the four lines has a 10K to ground.

One side of all the toggle switches goes to ground.
The other side of the toggle switches go to the LE pin on one of the 4511a. This one also has a 10K to supply for each LE pin.

One side of the case switch goes to ground.
The other side of the case switch goes to the BI pin on all the 4511s joined together. This one also has a 10K to supply.

If I've got this right, the display will blank when the case switch closes and reappear the same digits as before when opened.
The thumbwheel will select the number to be displayed.
The toggle switch will lock the number into one of the LEDs.

Brian.

 

[skarkowtsky]

We're almost there. If I have both the BI and LE wired, both with 10K resistors, to the output of the toggle, the latch works, but at first it shows a 0, then you have to remove the wire form the toggle and touch again and it shows the right number ( I haven't soldered this part yet until it's right). What am I doing wrong?

Ignore case master switch, I'm not at the step. This is all currently powered from a 9 volt, for this learning experiment.

 

[betwixt]

We're almost there. If I have both the BI and LE wired, both with 10K resistors, to the output of the toggle, the latch works, but at first it shows a 0, then you have to remove the wire form the toggle and touch again and it shows the right number ( I haven't soldered this part yet until it's right). What am I doing wrong?

Well done!
Removing the wire from the switch and touching again should do exactly the same as operating the switch, in both cases you break or make a connection. It's important to understand that the LE 'loads' the number into the display, it actually does it on the rising edge of the voltage as the switch opens. Until it sees that edge, it doesn't know what number to display. So nothing is wrong, it's just the way it works.

Brian.

 

[skarkowtsky]

It's not working. I even took a second toggle and wired the latch pin to that one with the switch always in on. It indeed does remember the number (no more 0 first), but I cant change the number after that, even if I turn the toggle for the BI pin on an off again. It will only change after I turn the latch pin toggle off and on.

I know this is functioning properly, but I need need to assign 12 unique 4-digit numbers. If the separate toggle for all the latch pins is set to ON all the time, they're all going to remember the first number set and get locked, no? That's what's happening now.

Any thoughts?

- - - Updated - - -

So,

I went back to just one toggle to for both the BI and LE pins. It's lighting up the led and freezing a number in the 4511, but it's always 0. I'm able to spin the thumbwheel with the led on, but it's always 0. If we can figure out to get it to freeze the thumbwheel number, this is solved. I keep trying different configurations, but my limited knowledge is a hindrance.

Any ideas how to wire both pins into one toggle, but get the right number to freeze and display? If so, this case actually works.

Thanks!
John

 

[skarkowtsky]

I DID IT!!!!!!!!!!!!!!!!!!

Allow me to preface this by saying how amazing circuitry is. I was completely uninitiated when I started this thread, but I didn't comprehend how a circuit forces you to think on a granular level, and then you actually begin to understand how all of these components feed off and control each other.

It turns out that I had some rewiring to do to make both toggles control everything just right. The wiring from earlier today was as follows.

Power from the 9 volt went to one toggle, which then fed the power to the thumbwheel and the BI pin. Sure, everything worked, EXCEPT the latching pin. I tried adding a second toggle that represented the master switch for the entire case, but I couldn't get it to "register" any number other than the first number dialed in when I powered everything up. I was forced to turn that second toggle off and on to update with the current thumbwheel number. However, that's not how the case operates in the film.

I then tried wiring the second toggle's power tab to the first toggle's output tab, in hopes that it would activate only after I turned the led on and reveal the number on the thumbwheel. That didn't work either. I've spent hours on this today, thinking about, and actually understanding (I don't know how that happened) all sorts of configurations until I finally landed on the right one. It wasn't a fluke or accident, it was the result of a deliberate thought and understanding of what I had wired up. I actually understand how this works. I still can't believe it!

The solution:

I needed a switch to the latch that was always on, but could be connected and disconnected from power at my discretion. The first thing was to reroute power to the thumbweel directly from the 9 volt, not via the first toggle that controls the BI pin (turns LED on and off). Having it connected to that toggle while trying to add another power switch for the Latch pin caused a problem where as when the latch was enabled, it only showed a 0 (resting state).

With direct power to the thumbwheel, which is distributed to the chip (minus the BI and LE pins) I wired both of those pins to the output of the second toggle, which is permanently in the ON position, then jumped power over from the first toggles output to second toggle's input. Now, when I turn the first toggle on to show the digit on the LED, it simultaneously turns the latch on, recording the current number. I can spin the thumbwheel all I want, but the number is already stored in the 4511.

When I turn the first toggle off, change the thumbwheel digit and turn that toggle back on, the new number is now burned into the 4511 register and displayed on the led!

Now I can set a 4-digit to any of the 12 LED readouts, flip the toggle for those digits, save that number in their 4511s, then change the thumbwheel number, flip a different switch and have a second unique number displayed on those 4-digits, and so forth. Up to all 12 readouts!!!

A MASSIVE thank you to everyone who helped, especially Brian. I'm certainly proud of what I was able to achieve, but without all of your combined knowledge, I wouldn't have been able to do it. And, we stayed faithful to 1988 technology, and most likely how the original was made.

Now to build 47 more of these, have custom plexiglass inserts made, then fabricate the actual prop. What did I get myself into?!?!?!

- - - Updated - - -

Here's a video of it in action

**broken link removed**

 

[betwixt]

Now you can see why multiplexing was invented!
Although not applicable in your design, it would allow the whole thing to be reduced to a hand full of components and probably 10 times cheaper.

Brian.

 

[skarkowtsky]

Haha, absolutely! But I priced this, $106.47 total.

So, can I use the 10k and 1.3k resistors for all??

 

[betwixt]

Yes, the values are not critical. The 10K for pull-up/pull-down resistors is just a 'ball park' value, you can safely use anything up to about 100K before any problems will show up. Too low just wastes current when the switch closes and connects them across the supply, too high makes it more prone to interference pick-up but that wouldn't be a problem in your device.

The 1.3K is (I think) the resistors in series with the LED segments. The value decides the current and hence brightness of the display segments, you could drop it for more brightness but it will reduce battery life so only do it if essential. In any case don't go below about 680 Ohms or the LED will be overloaded when the battery is 9V or more.

Brian.

 

[skarkowtsky]

Thanks again, Brian! For fun, below is the itemized list of parts required and purchased. It's enormous.

(1) 4-Digit Thumbwheel Switch
(48) 7-Segment LED
(12) Toggle Switch
(1) Momentary Switch
(48) Micro ON/OFF Switch (self-locking)

(1) 16 Pole Terminal Block
(1) 2 Pole Terminal Block
(2) Proto Board (4"x8")

(48) 4511 Chip
(288) 10K Resistor
(336) 1.3K Resistor

(1) Spool Solder
(1) Black/Red 2-Pin Wire (20AWG)
(10) Assorted Color Wire (22AWG)
(1) Battery Box

 

[skarkowtsky]

The micro ON/OFF switches to control the latching pins arrived. To my pleasant surprise, they have two sets of poles. Can I now power two of the four 4511s from one switch or do I risk crossing currents and such? It would cut these switches down from 48 to 24.

 

[skarkowtsky]

Hey gang!

Got all my components and will start wiring up soon. I'll post pics after I successfully wire the first 4-digit readout. Then I'll have to recreate another 11!!

Also, I just noticed the case in the film makes a single beep every time a toggle switch is set to ON to reveal a 4 digit number. So, after a quick Google search that led me to an eda forum post from May of this year, I now know to add 555 timer chips to achieve the beep. I also learned that I can control pitch, volume and duration of beep with resistors and capacitors. Pretty cool!!

D123, you were the member that posted all this, so thanks!

In the meantime, please click the link below (ignore the background noise) to see what I've done so far. I've soldered all new color-coded wires to the thumbwheel switch, including a new common lead through all 4 tabs. Although there is currently only (1) 7-segment connected in the video, the functionality you see with the ON/OFF toggle is how the entire case will work. I'll set 4 digits on the thumbwheel, flip (1) of 12 toggles to reveal that number on one set of 4-digit LEDs, then change the thumbwheel numbers and flip another switch all the way up to (12) unique 4-digit numbers off one thumbwheel all on at the same time! Super excited, but I'm looking at hundreds and hundreds of hand soldered points!

Enjoy!
**broken link removed**

 

[BradtheRad]

Yes, you're on track all right. Good going.

 

[d123]

Hi,

Nice work, thanks for posting the video! Great attitude you have there. I hope it all goes well putting it together. Happy soldering!

 

[skarkowtsky]

Thank you Brad, and D123.

D,

So I'm going to be connecting a 555 to each of the toggles, but I'm not connecting it to any part of the actual led circuit. Is it possible to just connect the beep pin? Also, the case will be powered by two 9 volts in parallel. Would you be able to recommend a capacitor for the 555?


Novice question, does the beep occur in the chip, or I need a mini speaker, too?

Thanks!

 

[d123]

Hi,

It's an actual beep? I seem to recollect is is a speaker. A buzzer may not produce the sound you're looking for.

The 555 doesn't make any sounds itself, just a high output pulse, it needs a speaker or a buzzer.

The capacitor (and resistor(s)) affect(s) how long the output pulse is, the supply voltage is basically unimportant in this respect.

Changing this circuit to a monostable/one-shot (it's an astable/oscillator) might be right for the purpose, I'm not sure what kind of sound this circuit produces. I can't tell you the capacitor until I know know how long the beep has to last. That's easier done by calculating and then breadboarding to tweak the results.

I'd OR the toggle switches.

Better yet, you could make this TOY ORGAN Circuit with only one "button" (toggle switch input) so one tone only is produced. That or try each "musical note" with this version and use the "best" sounding one. I'd still OR the toggle switches, it would only need 3 (CD)4071s for 12 switches. I recollect it sounds a bit hideous so might not be the sound you're looking for. Real world experimenting with these circuits is the only useful way to find (an approximation to) the sound you actually want.

Pin 5 in the toy organ circuit should have a 100nF capacitor to ground.

I strongly recommend this website for any extras or workarounds you may want with the 555 in general LM555 and LM556 Timer Circuits. Rob Paisley has some splendid timer circuits that are reliable and work, plus a load of information to understand the device, and calculators.

Let me know if there's anything else.

 

[skarkowtsky]

Thanks, D.

In the post below, you shared a diagram and I believe that's exactly what I need. Can I just replicate this?

https://www.edaboard.com/showthread.php?377531-I-need-a-short-single-quot-BEEP-quot-circuit


Also, within that post you shared a video, and that's the exact tone I need. I need one beep as soon as the toggle is flipped with a duration of about 1/4 - 1/2 second. Like a blip. If we can do that, it will match the movie perfectly.

https://youtu.be/zyhVpvTOWVA

 

[d123]

Hi,

That seems to be right. IU'd say you certainly can . Posts #16 and #17 are the right circuit that go with the video. I'd forgotten that one. I assume the buzzer choice is quite important looking at the disgruntled answers of the thread poster unless they were getting something or other wrong... IF you need that exact tone and don't want to chance it on random purchases, try and get hold of that specific Velleman buzzer somehow.

At a guess, I'd change C5 to anything from 100nF to 220nF and maybe even 470nF for the 1/4 to 1/2 second duration you want and you might need to - but not necessarily - change C1 from 10uF to 2.2uF or 4.7uF.

You do need to breadboard that circuit to a) check the buzzer is appropriate to your needs, b) it works with OR gates and c) find the duration and sound you want, and to play it safe going from breadboard to pcb it would be wise to make R2 47k followed by a 100k 10-turn to 20-turn trimpot (maybe a cheap 1-turn will more than suffice but I'm not keen on them) set midway and probably twiddled a little to get the timing right (i.e. the same as the breadboard version you'll try). Ditto for R3, a 100k fixed resistor and a 100k trimpot set midway. These things are never so precise from breadboard to pcb so if you want "fussy" I'd play it safe and include trimpot(s).

Just as you've done with the seven-segment display circuits, do breadboard it first. Sorry for repeating myself so much but 555s from breadboard to pcb tend to change a little or a lot r.e. RC timing. Breadboard is not PCB, capacitors used may have more or less capacitance unless you use the same ones used for the breadboarding.

I wouldn't use 12 555 circuits unless strictly unavoidable - I'll bet the resultant beep will be slightly different for each one. Again, just three OR quad CD4071s for the twelve toggle switches and a fourth CD4071 quad OR gate that the three previous ones are fed into. I haven't made the beep circuit adding OR gates so I will simulate it tomorrow evening if I get the chance to see if it still works with logic between switches and 555. I have no components where I am at present so can't do a real world check, I'm afraid.

 

[skarkowtsky]

Thank you, I'll have to re-read this a few times, abit over my head, haha! I also found a 555 circuit websites with schematics and parts list. I think I might have found a circuit for a one time beep, but it needs a slight modification. If I'm following it correctly, it's activated by a switch but stays on. Can we tweak the below link so the duraction is 1/4 - 1/2 second?

https://www.555-timer-circuits.com/latch.html

 

[d123]

Hi,

I'd need to look at that better tomorrow to figure it out.

My idea has a few flaws from what I've seen... I'll post this modified version which we can consider a nice idea but a bit of a fail: see how the pulses get shorter with each consecutive input Oh dear, either OCD modifying to see if it can be improved or right back to the drawing board...

You can experiment with timer circuits and the toggle switches on breadboards yourself, it's a very user-friendly IC with many resources online...

Comic relief:

 

[d123]

Hi,

Theoretically, got it right now. The capacitor from the inverter output into pin 2 of the 555 is something that appears in a Rob Paisley circuit for triggering a monostable from a long input pulse if I remember well.

The TLC555 maybe should be the SE555 (or SA555, NE555, NA555, LM555) in reality. I have a minor doubt as the CD4069 is a CMOS device and the SE555 (TTL) is presumably but not necessarily compatible - without my components here I can't check a breadboard version. The TLC555 and LMC555 are CMOS timers... If you can wait a week, I might have more of my stuff here by then and be able to check it unless you have already.

In the simulation the output high is 0.5 seconds.



ATTACH=CONFIG]150032[/ATTACH]

If the CD4072 (dual four-input OR) were used, only two packages are needed, rather than four CD4071 (quad two-input OR) packages.