Down in Corsicana, TX at the home of Don and Rita Capehart. We did lots of hard labor these last two days to crate up these panel frames for shipment to Seattle. Got a few other goodies too!
Telephone system, 1908
Removing the gearbox from the office frame to borrow the cork roller. Our incoming frame roller is getting worn out, and we have 4 selectors that we can no longer use. Borrowing this one will allow us to remove the bad one and repair it on the bench.
Before / After
Literally just finished a few minutes ago! 😄
Omg you guys I am still working on this project. It will actually never end. But hey, look! I got a bunch of wires connected to the fuse panel!
…and I have a bunch more left to do ☺️
Attention
If I can no longer update this blog, or it gets shut down, I will post the new blog location on the museum’s twitter @museumofcomm
Wrote a simple web interface and an HTTP server for my traffic generator. Now I can start and stop it with my phone!
Sorry everyone it was nice knowing you. Tumblr does not approve of my machine switching kink.
How deep does the rabbit hole go??? 😂
Sorry everyone it was nice knowing you. Tumblr does not approve of my machine switching kink.
Where should this blog move to once tumblr becomes a deserted wasteland?
Even if it doesn’t, I kind of don’t want to support tumblr anymore. It’s a matter of principle.
The view from my office today. Soldering upside down on my back is a real pain in the everything!
dfroula asked:
Looking at the photos of a selector frame, I can see 4 panels within the frame that I believe must correspond to the 4 Groups of the selector. I am wondering if the 5 Banks (associated with Brush selection) are all integrated within this one Group panel?I'm thinking this must be the case for a Brush selection to choose a Bank, otherwise some vertical motion would be required. I hope that makes sense.
The brush selection method is actually quite ingenious! Let’s assume a very simple panel frame with only one selector rod on it. On a selector frame, there are 5 banks, plus the commutator bars at the top of the frame. Each of the 5 banks has a brush associated with it, mounted on the selector rod. Each of the 5 brushes that pass over the 5 banks (numbered 0-4) has a trip finger associated with it. During brush selection, the brushes move upwards from their home position a tiny amount–between 1 and 5 clicks, which amounts to an inch or so of travel.
To select brush #0, the rod will move up one click, which puts the 0 brush in line to be tripped by the #0 trip finger as it continues to move upward.
To select brush #1, the rod will move up two clicks, which puts the 1st brush in line to be tripped by the #1 trip finger as it continues to move upward.
To select brush #2, the rod moves up three clicks, which puts the 2nd brush in line to be tripped by the #2 trip finger as it continues to move upward, and so on…
Once the desired brush is in position to be tripped, it stops momentarily, and a magnet engages and rotates the entire trip rod. This rotates all 5 brush tripping fingers about 60 degrees. Once the magnet is engaged, the brush rod starts upwards once again. As the brush continues upward, it drags against the rotated trip finger and “snaps” the brush closed onto the bank terminals.
Here’s the genius part: The height of the trip finger is different for each of the 5 brushes. If the 0th brush is to be tripped, none of the others will be, because they are not at the right height to be engaged by the 4 remaining trip fingers as the brushes move past them. Even though all of the trip fingers rotate to engage the brushes, the remaining brushes will just slide past them without tripping, and they don’t interact with the multiple banks–they’re just along for the ride.
When the call is hung up, and the brush rod returns to its home position, the brushes hit a shelf that they rest on. The shelf resets the tripped brush by pushing the brushes trip arm back to the untripped position, sort of like how you might fold up a pocket knife on the edge of a table before you put it away.
Hope that helped!
The wiring nightmare continues!
1. Current wiring
2. The splices I got done yesterday.
3. Final layout of the form when I’m done.
It looks so easy, doesn’t it? It isn’t.
It’s boring. It’s monotonous. It’s never ending. One mistake can mess up the who thing and probably won’t be noticed until well after the project is complete. The only way to fix it is to tear it down again and check each splice.
You’re absolutely right. Wiring is a really underappreciated art, and I only realized this after tons and tons of practice, and watching myself get better and better at it. This is definitely not something I would have been able to do 3 years ago when I started.
This particular job has a couple of problems that compound to make this really finicky and problematic:
- The original wires are old and brittle.
- The cotton wrapping is coming unraveled, and is falling apart.
- The colors aren’t visible for most of the length of the wire, which means that I have to tone out each of the (over 300) leads one by one.
- I need to create a nice form out of this mess, but in order to do that, I need to cut the existing plastic covered leads that are running to the selectors and fuses (first photo). When I do this, it will take the entire frame out of service. After that, there is no going back. I have to then connect all of the leads together, making sure to break out the leads to the fuse panel and ground bar, and also include the miscellaneous leads from the alarms, interrupter, and test lines.
I checked, and there is unfortunately no way for me to work my new form into the existing mess. My plan is to do everything I can before I cut the plastic wires out, so I won’t have to take extra time during the joining phase. That’s the part that makes me nervous.
The wiring nightmare continues!
1. Current wiring
2. The splices I got done yesterday.
3. Final layout of the form when I’m done.