I got a friend who works for small start-up in a rented office. His problem is that they have only a single remote control to operate the parking lot gate. They needed a device that will allow them to open the gate by using the cell phone.
I built a device that connects to a phone line and to a standard remote control. The device is actually a “docking station” for the remote control. When a ring is detected the device will “press” the gate-open button on the remote control.
Telephone Operated Car-Parking Remote-Control – [Link]
Today, most telephone equipment use a DTMF receiver IC. One common DTMF receiver IC is the Motorola MT8870 that is widely used in electronic communications circuits. The MT8870 isan 18-pin IC. It is used in telephones and a variety of other applications. When a proper output is not obtained in projects using this IC, engineers or technicians need to test this IC separately. A quick testing of this IC could save a lot of time in research labs and manufacturing industries of communication instruments. Here’s a small and handy tester circuit for the DTMF IC.
MT8870 DTMF Telephone Dial Tone Decoder - [Link]
Yes folks, it’s time for another horse to bolt from the Downunder stable of telephone intercoms (unfortunately before the gate could be shut on it…) and other zany electronics type ideas. The circuit you are about to see is the culmination of some effort at improving the basic Link intercom design. You may think that pulse dialing is ‘old hat’ nowadays, but the exercise of building and testing the Link ‘P’ in this format, and understanding how it all works, is well worth the effort. Not to mention all those out there who have the old style rotary dial phones as collectables – you can now make them work for you, or display them actually working with confidence.
The Link “P” – Privacy Link! (Telephone Intercom) - [Link]
This is a very small telephone exchange attached only two ordinary Tele phones. Fully bi-directional facility with an intercom system. When a phone is in off hook condition , Exchange will detect it & send ringing pulse to other phone. When it will be picked up , the connection will be established between both phones. This will be taken place vice-versa.
Two way Simple Very Small Telephone Exchange - [Link]
This is a well-documented solution for storing unlimited caller ID phone numbers. The site contains schematics and the software needed to decode and store the data.
Some time ago, I subscribed to the Caller Id service to know who is calling me without being required to pick-up the phone. Unfortunately, my basic caller id display could not memorize enough numbers, and I had to write them manually in a computer to keep them. That’s why I decided to find a way to log the calling numbers directly to my computer. [via]
Caller ID decoder - [Link]