Multi-Line Telephone Intercom -- Episode 392

The buy kit only included about 4 items in it. I have to invoice someone and it helps to limit the numbers of suppliers...

I ended up ordering the cheapest PBX I could find as it's also a goal of mine to learn how to configure those.  

I was also about to buy old magneto phones and have us crank ... crank call? LOL when we needed to use the system.

Hi Aaron,

You can substitute most of them, but the HT9170D comes from a single manufacturer, if that's the one that is not available, you'll have to obtain it elsewhere. The other parts will (or should) have many substitutes, if you type the part into the Newark/Farnell website search box, it will make alternative suggestions for you normally. I'd be surprised if any of the others are not available because they are generic parts, but if you can mention the ones you're having a problem finding alternatives for, that makes it easier.

It looks like the components are no longer available as a kit as of 2020
I'm dreading buying components from a bunch of places.  Anybody at element14 able to recommend alternate components that are in-stock?

Am a student I need your help in how to make this as a project, so I need you to put me though and some journal I can read about to make the project possible.

THANKS

Hi Jimmy,

Unfortunately I can't recommend a specific transformer as I bought a handful of old power transformers from the local surplus to try out. 120v to 18vct w/ 450mA secondary turned out to be the winner. The main thing is you don't want the primary winding resistance to be too low, otherwise it's like trying to drive a short circuit. Sorry I couldn't be more helpful, but this is the one component that required some experimentation.

Best regards,

Derek

Great project. Im trying to replicate the ringer... any chance you could put up a link to suitable transformer. I am just making the phone ring (old analog bell type) so i dont need to woory about noise on the line.

This is awesome. I have been looking to do something just like this for a while. Is it possible to get some pictures of the actual cards you made themselves? I’m not very good at transferring a schematic to a physical layout from scratch and I like how compact yours is.

Cool project.

I once worked for a phone company, but they never explained how they worked, I was just a repair person.

Thanks

DAB

Saying "current source" out loud always sounds weird to me now.

Thanks! It was fun to make.

I thought it was appropraite your block diagram has a current source in it.

Also, I think I forgot how to DTMF worked! I knew there two tones, but I didn't know they are determined by the phone pad's matrix.

Nice project.