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I know a quick way to fix that problem. Lay your ipad on a sturdy table. Go find the largest hammer you can find. Vigorously smite said ipad until thoroughly transformed into the sum of all its parts.
I've thought of that many times. Then replace it with what? I'm considering buying something new.
 
...I would introduce a small(but very large improvement) change into the system. I would use a PLC to operate all the controls, but have the 'old school' switches/lights to be the inputs/outputs. The PLC would be hidden, so it would look like and operate just like it had relays. It would make things very simple and you would have a fraction of the wiring to do. With todays technology, you might even be able to save money on the PLC vs relays and such.
I believe that is what he is doing.
Yes and no. Programmable logic circuits (PLC) (see link for those new to this) requires programming for it to operate. I am sure I can program straight forward sequential steps. But I am not savvy about including all the what if/not scenarios - like when some kid throws a switch to drop the bridge span on the passing boat, or any other out-of-sequence situation. So I rather prefer old fashioned logic Integrated Circuits (ICs). I can program them in terms of swapping around the IC's (gating modules) like logo bits. and their inputs and outputs are analogue components (switches, etc).

I am sure I will be using micro PLC units in future museum projects. The museum is upgrading itself to incorporate interactive displays to promote greater interest and easier education. This project is its introductory piece. In the meantime I will be learning about micro PLCs with an old Raspberry Pi a museum staff member loaned me.

So in a way, for this project, I am making my own PLC out of logic ICs.
 
Yes and no. Programmable logic circuits (PLC) (see link for those new to this) requires programming for it to operate. I am sure I can program straight forward sequential steps. But I am not savvy about including all the what if/not scenarios - like when some kid throws a switch to drop the bridge span on the passing boat, or any other out-of-sequence situation. So I rather prefer old fashioned logic Integrated Circuits (ICs). I can program them in terms of swapping around the IC's (gating modules) like logo bits. and their inputs and outputs are analogue components (switches, etc).

I am sure I will be using micro PLC units in future museum projects. The museum is upgrading itself to incorporate interactive displays to promote greater interest and easier education. This project is its introductory piece. In the meantime I will be learning about micro PLCs with an old Raspberry Pi a museum staff member loaned me.

So in a way, for this project, I am making my own PLC out of logic ICs.


Just out of curiosity...

What are you planning on using for limit sensors and switches?
(Something to turn off the motors).
You can't count on people to actually turn a switch at an appropriate time.
 
The museum allocated a display space which was larger than I anticipated. I was hoping for making the working portion of the bridge to be placed in front of, and no wider than, the console. Instead I got a huge 2.4 x 1.2 x 2.4 m (8 x 4 x 6.5 foot) space. The curator suggested to build the whole bridge :shock. I thought, well in that case we might as well build a diorama (with landscape). The length of the bridge fits nicely into the space using the common modelling scale of 72:1. This makes it easy to add already made cars and figurines (people) into the diorama.

So me plan got extended to hopefully look like this:
xaLi3Yi.png

As you can see, a working boat has also been requested for the project (to make it even more interesting and educational). There is nothing like a challenge to test your faith in Christ's unlimitedness (unconditionality).

The allocated space already had a steel frame for supporting displays. This meant that the display tabletop already had a minimal height to it. However, the console itself is adult size, and too tall for the steel framework. I had to adjust this height for both adults and older children who are more likely to be using the console.
Here is a drawings to give you an overall picture of the display.
Hwp4qQ0.png
 
Just a word about the photo eyes...
As I have experienced they can be kinda tricky and sometimes ornery to get adjusted correctly. Be patient and consistent when adjusting them...
Thanks for tip. I'll keep that in mind when selecting the thickness of the blade that inserts into the slot.
Also, your suggestion reminded me that an optocoupler will be used on the lift-span to limit its maximum height (there will be a microswitch as well for backup). If the staff switch off the museum lights, but the display is still powered, then the optocoupler would detect a broken light path. Hmmm. I will need to make sure that the optocoupler is only operational while the lift-span is unlocked for movement.
..You going to use an electro-magnet (under the tank) and a piece of steel (in the boat) to get the boat to sail through the bridge?
I thought of that, but decided to go physical and use a slotted pathway (through the display tabletop), with an aluminium sheet, as a keel, passing through the slot. It will be driven with a pulley system. The motors donated for the project are standard DC motors with a 148:1 gearbox. I thought of using stepper-motors, or servomotors, but they are too expensive.
 
Since we have been talking about the drive systems, here is my plan for operating both the lift-span and boat.
Hkhxm8t.png

SM = Span Motor
BM = Boat Motor.
Both will be located in a Control Box under, and attached, to the display table.
The plan drawing (left) is a floor plan for the Control Box.
 
What was the location of the old span bridge?

Funny I just saw a piece of one in a front yard today
 
I am jumping a few steps ahead of myself to post some electronics. Here is the circuit diagram for the Power Supply Unit (PSU) as mentioned in Post #15.
m9EztYm.jpg


Below are photos of making the Printed Circuit Board (PCB).
B38bYkJ.jpg

Note: The original aluminium heatsinks came from old computer PSUs, cannibalized and reused here.

Below are photos taken while testing the three output DC voltages.
XF2ZKic.jpg
 
Yes and no. Programmable logic circuits (PLC) (see link for those new to this) requires programming for it to operate. I am sure I can program straight forward sequential steps. But I am not savvy about including all the what if/not scenarios - like when some kid throws a switch to drop the bridge span on the passing boat, or any other out-of-sequence situation. So I rather prefer old fashioned logic Integrated Circuits (ICs). I can program them in terms of swapping around the IC's (gating modules) like logo bits. and their inputs and outputs are analogue components (switches, etc).

I am sure I will be using micro PLC units in future museum projects. The museum is upgrading itself to incorporate interactive displays to promote greater interest and easier education. This project is its introductory piece. In the meantime I will be learning about micro PLCs with an old Raspberry Pi a museum staff member loaned me.

So in a way, for this project, I am making my own PLC out of logic ICs.

Yea, I work mostly with PLC's, but 'dabble' with plain IC's from time to time. I am a visual kind of guy, and the PLC's are really nothing more than a bunch of IC's that can be configured to do different tasks based off how you set the program. But it does take a little different approach than just using the IC's individual components.

If in the future you want to dabble with them, a very easy/inexpensive way to get into them is the CLICK line of PLC's from AutomationDirect. We use a few of their 'cheap' line for some of our process controls and I am VERY impressed with them. The programming software is free, and pretty simple/straightforward.

Anyways, I just thought I would throw that out there. My neighbor is a retired electrician from Michigan who used to work at the Ford plant. He started there when they had HUGE walls of relays and controls that operated the plant, and by the time he retired they had condensed it all down to a tiny fraction of the space using PLC's. It's one of those things I find interesting. :)
 
Make sure ya have liability insurance & have a Licensed Engineer sign off on it, so if there's a problem in the future it protects ya.
 
Back to building the display.
The display is too big to have in the small museum workshop. I opted to build it at home, in my lounge-room come studio. So now it has become a workshop. I am a hermit with nobody to appease in my abode, so I don't have a problem with being cramped in.

After the timber got delivered I measured it all out, cut it all up. then assemble all the bits.
The plywood boards were attached by countersunk screws. They later got wood-putty filled and sandpapered.
PS: now you can see where I sit to eat my meals and type out my posts from.
xy70pBE.jpg


The Control Box for under the tabletop. It has two swing-down doors for accessing the motors, cabling, and electronics.
qfqDpjr.jpg
 
About these posts. My faith in God has been and will remain tested. Every step, or task, is not done without some awareness of prayer and praise. The above post, even when I look at it today, I know that God's hand was available in mine whenever I was unconditional (fearless) in what I was doing. As soon as I doubted, I was tested to make the right decision. Even if the job went sideways, the right decision was the same, to accept it.

Now came the actual stage of bridge building. It did not go without some apprehension (fear). For me, any tension is a reminder of "You must believe". "Where is your faith". Those words were often said by Jesus Christ. So I get reminded daily of those words.

Making and installing the bridge footings.
tmhiqS0.jpg


Installing the bridge piers.
a6wkewy.jpg


Installing the bridge girders, lift-span base-plate, and a street underpass.
ch4ypGX.jpg


It is in itself nothing compared to what others have built. However, this sort of creativity is new to me. It is so awesome to play, with God on your mind. I know that many of you experience at times "I don't believe I done that. Divine intervention must have been involved". Some call this 'inspiration' (spirit led). Well that is how I feel it is for me on this project.
 
Before adding the road base, I needed to give the accessible parts an undercoat of paint, and while I was doing that I also decided to painted the river part.
Note the holes along edge of pier ends. These will become electrical contact points for the lift-span when docked. This will allow power and signal data to the span. The span will be self-empowered via a rechargeable battery within it. This is so I don't have to have wires fatigued by, bridging to the span, being always under stress and movement.

The raw timber sections is for adhering foam material that will be shaped for landscaping the riverbanks.

6JjwX6M.jpg
 
Needing a break from woodwork, I started to cannibalize every bit of electronics I could get my hands on (unserviceable computers, DVDs, a radio, and an analogue TV set. That is where I got the heatsinks for the PSU mentioned earlier.

Now I had a pair of small speakers, from the TV set. I wanted to incorporate them into the console for sound effects. That is, for the bridge alarm bell (before bridge operations), and a diesel engine sounds of the boat chugging along as it passes under the bridge. However, the speakers themselves needed a bracket so as to keep its paper diaphragm from contacting anything, or else the sound will get muffled.

arHBnW9.jpg


The Console will be connected to the Control Box via cabling. I used computer/data D-Connector sockets for the Console. The console now needed several holes to be cut out to hold the cabling sockets, the mains power socket, and the two speakers.

OLF5RUZ.jpg


The museum president said it would be good to post some photos of the console internals on the display backdrop. So as to give school children an idea what was involved inside the console. I suggested to let them actually see the internals via a thick sheet of perspex, and even have it lit with LED strips. So now the console has also turned into a wiring diorama (me and my big mouth) :rolleyes.

This meant that the interior needed to be cleaned and painted. I decided on a darkish blue in the hope of highlighting the coloured wiring. Ironically, the shade I chose was called Boatshed Blue.

exk7G08.jpg
 
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