Port-O-Rotary

Description: A cellular rotary phone - the dialing takes a long time! In Colorado, with a 10-digit dialing system, one must be careful not to make a mistake when entering a number. Where can one purchase a rotary phone these days? Interestingly, there are several options available on Froogle, but many of them feature push buttons disguised as a rotary dial. This is not desirable. The Senior Store offers rotary phones specifically designed for seniors. However, the price of $49.95 seems excessive. BoldOldPhones is another valuable resource for rotary phones, offering a variety of colors. Additionally, eBay is a well-known marketplace where various rotary phones of differing qualities and ages can be found, typically priced around $20. A 1957 'Automatic Electric Company' rotary phone was purchased for $10 plus $8 shipping. However, the auction indicated that the phone had an 'original tone ringer,' suggesting it had been upgraded. A search for another rotary phone with the traditional bell ringer is now necessary for the Port-O-Rotary v2 project. The components of the rotary phone will be replaced with modern technology. The phone was disassembled, cleaned, and inspected, revealing signs of previous use by a smoker. The rotary mechanism operates by opening and closing switches; when the dial is twisted, it does not engage until it is released, at which point it returns to its original position. The grey oblong wheel rotates once for every two numbers dialed, which simplifies the process. Close-up images of the rotary element illustrate the mechanism. The two paddles at the top are slightly apart, with a protective liquid gel ensuring no visible gaps. A resistance meter confirms that the system toggles on and off. Another image shows the rotary in its resting position; the bottom paddle opens when the dial returns, indicating the end of the dialing process. A PIC microcontroller will be used to register the on/off clicks. The connections to the various pins are outlined, with a focus on an SSOP version designed for another PCB, though it is conceptually similar to an 18-pin DIP. The internal 8MHz clock will be utilized at 3.8V, ensuring caution with the non-16LF88 part. The 'End_Rotary' pin connects to the lower paddle, while the 'Rotary' pin connects to the upper paddle, which indicates when the phone is lifted off the hook. The system includes two complementary paddles linked to ground. PORT B on the 16F88 features internal 10K pull-up resistors, which, when activated, allow 'End_Rotary' to register a '1' while a number is being dialed and a '0' when the rotary is in its normal position. The 'Rotary' pin will register a '0' each time a number is passed and a '1' otherwise.

The rotary phone circuit operates fundamentally on the principle of mechanical switching, where the rotary dial's motion translates into electrical signals. The internal mechanism consists of a series of contacts that open and close as the dial rotates. Each number dialed corresponds to a specific sequence of electrical pulses generated by the movement of the dial returning to its resting position. The PIC microcontroller, configured to interpret these signals, can be programmed to convert the pulse sequences into recognizable digital signals that correspond to the dialed numbers.

The connection setup includes the use of pull-up resistors to ensure that the input pins on the microcontroller are in a known state when not actively driven by the rotary mechanism. This design minimizes noise and false triggering. The microcontroller's firmware must be adept at distinguishing between the rapid pulse generated by the rotary dial's return and the stable state when the dial is at rest. By employing interrupt-driven programming, the microcontroller can efficiently handle the input from the rotary dial, allowing for accurate number recognition without missing any input during the dialing process.

In addition to the basic functionality, enhancements could include integrating a digital display to show the dialed number in real-time, or even adding Bluetooth capabilities to connect the rotary phone to modern smartphones, allowing for a unique blend of vintage design with contemporary technology. The project could also explore the use of a small speaker to reproduce the traditional ringing sound, providing an authentic experience while maintaining the reliability and convenience of modern electronics.A cellular rotary phone - the dialing takes forever! And here in Colorado - on a 10-digit dialing system - you don`t dare mess up the number. Where do you even buy a rotary phone these days Oddly enough, there are quite a few phones on Froogle that had push buttons within the faux rotary face. That won`t do. How about the Senior Store ! No really - they sell rotary phones for seniors. Cool, but $49. 95 is a bit too much. BoldOldPhones is also another great resource for rotary phones. They even have colors! Where else to look Ebay of course! You can find anything! There are quite a few people selling rotarys of different qualities and ages on Ebay. Most are ~$20. We got our 1957 `Automatic Electric Company` rotary phone for $10 + $8 in shipping. Not too shabby. Whoops. The auction alluded to the `original tone ringer` which looks like they meant the phone was upgraded. Oh well - I`ll have to find another rotary with the old bell type ringer for Port-O-Rotary v2. Now those are some components! Time to replace them with technology of the 21st century. I tore the phone apart, wiped everything down with some warm water and elbow grease. On a side note, I think the previous owner was a smoker. Here`s a couple photos of the rotary element up close to help you get an idea of what is going on. Basically, the entire system is just the opening and closing of switches. When you twist the rotary around, nothing much happens. When you let the rotary go, the dial starts turning back to its original position. As it does this, the grey oblong wheel spins once for every two numbers. Two numbers That seems silly. Actually, it makes it very easy. This picture is about as good as it gets and it`s still not very good. You can see the top two paddles slightly further apart. There seems to be some nice liquid gel that is protecting the paddles so they never actually have an visible open space.

But if you hook up a resistance meter, sure nuf, the thing is toggling on/off. Ok, that seems easy enough. Now this is another important picture. This is the rotary in the finished, or non-turning position. Take a look at the bottom three paddles. When the dial has returned to the finished state, the center brass column exhorts pressure on the black pin, opening the very bottom paddle. Thus, you can tell when the rotary is finished spinning! Ohhh, this is almost too easy! Now we just need a PIC to take a look at the on/off clicks. Here are the connections to the various pins. This is a SSOP version that is being design into another PCB but just imagine it`s a 18-pin DIP. No crystal, uses the internal 8MHz because at 3. 8V on a non-16LF88 part, we`d better be careful. `End_Rotary` is connected to the lower paddle. `Rotary` is connected to the upper paddle. `Hook` is connected to a similar paddle within the upper rotary mechanism that tells you when the phone is lifted off the hook or not - it`s surprising simple.

There are two complimentary paddles (one for the hook circuit and one for the rotary circuit) that are connected to ground. PORT B on the 16F88 have internal 10K pull-up resistors. Turn them on and you`ve almost got the hardware wired up! So with the internal pull-ups on, `End_Rotary` will see a `1` while the user has activated a number and the rotary is returning - and a `0` when the rotary is in the normal sitting position.

`Rotary` will see a `0` every time a number passes by and a `1` every other time. Actually, it a