Telephone Hold Button
Although a hold feature is standard on most new phones, a lot of us still use the origional bell phones. Those of us that require a hold feature will find this circuit very useful. It is easy to build, and is compact enough to be installed inside the phone with no real problem. It is also powered by the phone line itself, eliminating the need for batteries.
Schematic
Parts
| Part | Total Qty. | Description | Substitutions |
| R1 | 1 | 1.5K 1/4 W Resistor | |
| R2 | 1 | 1K 1/4W Resistor | |
| D1 | 1 | 1N4002 Silicon Diode | 1N4003, 1N4004, 1N4005, 1N4006, 1N4007 |
| SCR1 | 1 | C106Y SCR | |
| LED1 | 1 | Red LED | Green LED, Yellow LED |
| S1 | 1 | Normally Open Push-Button Switch | |
| MISC | 1 | Wire, Board, Case (If Used) |
Notes
1. To place a call on hold, simply hold down the button while hanging up the phone. To take a call off hold, just pick up the phone, or any extension.
2. Even though this is a simple circuit, you may have to check with your phone company before use.
Title: Telephone Hold Button
electronic circuit
Source: www.aaroncake.net/circuits/
Published on: 2005-02-10
Reads: 368
Print version: 
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