Phone Dialer eBlock

Figure 1 - Phone Dialer eBlock

The phone dialer eBlock is designed to remotely alert a user of an event using the phone line. On startup, the dialer eBlock prompts the user to program a phone number to dial in the future. After the number is entered using the keypad, the eBlock goes into hibernation mode, waiting for a 'YES' packet to be recieved from the eBlock input. At the time a 'YES' packet is recieved, the phone dialer eBlock dials the programmed number, waits for approximately 30 seconds, and then goes back into hibernation, waiting for another 'YES' packet.

There are limitless possible applicatons for the dialer eBlock, the most obvious being home security. An eBlock motion sensor can be attached to the phone dialer and placed inside a home and programmed to dial a cel phone. If an intruder were to enter the house, the motion censor would trigger the dialer, which would then silently dial the cel phone to alert the homeowner of the intrusion.

The components used to construct the dialer are as follows:

  • Intel 8051 - Used to control DTMF transceiver, LCD, and Keypad.
  • PIC16F628 - Used to recieve eBlock packets and notify the 8051 when a 'YES' packet is recieved.
  • MT8880 DTMF Transceiver - Generates DTMF tones to be transmitted over the phone line. Used as a transmitter only in this design.
  • 600:600CT Transformer - Transforms DTMF tones generated by MT8880C to 0-48v ring/tip interface for phone line transmission.
  • 5v Electric Relay - Used to open phone line when necessary to dial out, and leave line "on the hook" when not dialing.
  • DMC 16117A LCD - Mono 16 char LCD used to display user input and show status.
  • 16 Button Matrix Keypad - For user input.
  • Various resistors, capacitors, switches, etc.
Useful Links: