Miscellaneous
| Circuit / Schematic diagram | Description |
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Able to handle nine telephone set at different location using a single telephone line. |
| Hold Tone for Telephone | Based on UM66 |
| Telephone hold with music | |
| Door Phone Intercom | |
| Full duplex door phone | |
| DTMF Tone Decoder | Displays telephone numbers decoded from tones |
| Simple PBX | |
| Message waiting flasher | This circuit starts flashing when the phone rings and continues flashing it until the phone is picked up to remind you to check your voice- mail. |
| Telephone in use indicator | It will allow users to know if the phone is being used. |
| Off line telephone tester | Test telephone equipment without connection to a telephone line |
| Single number auto dialer | Always dials a single number when handset is lifted |
| Cellular phone base audio mute switch | Mute your audio devices when a phone call is received. |
| Cut phone line detector | Detects the discontinuity in telephone line. |
| Phone line tester | |
| Secrecy for Parallel Telephone | |
| Telephone Line Vigilant | Protects the misuse of telephone. |
| Four line internal intercom | This Link provides four internal intercom phones with no outside line access. |
| The Link telephone Intercom | |
| The Link telephone Intercom 2 | DTMF version |
| Two phone line link | This is the circuit that sparked off all the other Link Telephone Intercom designs. |
| Telephone dial alarm | Microcontroller based. |
| Telephone line base audio muting | The circuit would automatically light a bulb on arrival of a phone ring and simultaneously mute the music system/TV audio. |
| Telephone based Remote Control | It enables switching ‘on’ and ‘off’ of appliances through telephone lines. |