Phone Line Simulator - DC Loop Current and AC Ring Voltage Experiments 

Been waiting for this! Thanks for taking the time to work this project into your schedule :D

Oh yes, I was actually looking for something like this!

It always amazes me how much you can cram into a sub 7 minute video. Fantastic work.

When I first stumbled onto you channel You were going to do Modem stuff. I subscribed back then, And now you are finally doing it. Looking forward to more.

Cool phone project!

I would love to set up my modems on my msdos computers and use them with Doom for deathmatch play. I used to do this with my friend back in the days.

now that is a cool project

Just today I was dealing with the -48vdv 5200amp unfused Power Distribution Setup in a Telephone Building. It’s pretty wild.

Phone lines are so old school ;-) Just waiting for fibre to the house now, so i will lose my copper connection as its not being supported anymore. We are being pushed to VOIP phones only now! so bang goes my 50V 10mA power supply.

Extraordinario video. Gracias por compartir. Saludos

Cool project. What I'm on the lookout for is a device that will let me use my rotary dial phone with Google Voice.

Wiki isn't always right. While your in the correct direction, it's not exact. The phone system works on -48V not +48v. Secondly, when you pick up the phone there should be 300 ohms resistance. you shouldn't have a voltage of more than 1-2v because picking up the phone creates a "short" on the pair. The phone system rings on 100V AC sent from a ring generator from the central office at 20 cycles per second. In the old days it would pass through a "half ringer" circuit which is really nothing more than a capacitor and zener diode located in the NID or "network interface device" on the outside of the home and then into the home to 1 or more phones. On a rotary phone a user who could not dial the rotary could simply take the phone on and off the hook rapidly to dial a number. The switch at the central office could decode this. Today I rarely see rotary phones but they are out there. The signal travelling on the pairs down the road is shielded by twisting the two wires together. This creates shielding from interference and allows the DC to carry across the pairs without interference for miles. I got side-tracked....anyways, If you use an NE555 timer to control a relay you could reproduce the ring on and off frequency. The ring generator is always on and functioning in the central office. It connects to a line when the switch sees an incoming call to a customer. When a person A calls person B, The ring generator rings person B for a few seconds, then rings person A for a few seconds, back and forth. So person A knows it's ringing and person b knows they are getting a phone call.

I've been looking for a way to do this over the internet. Perhaps you can squeeze 2 raspberry pi's connected by LAN in between those two RJ11 ports?

You could throw in a half-wave rectifier. This would take your 60hz to 30hz. Closer to 20hz then 60hz.