Hold Button

[greg123]

Hey, How can i make a cheap hold button for my phone......too lazy and cheap to buy one with a hold feature.<p>THanks

[haklesup]

Cheap maybe but not lazy. Buying an electronic phone with a hold button is easier than building one.<p>I found 2 curcuits in my books. One is complicated with lots of components but one is very simple<p>Draw a circuit with the red wire at the top and the green at the bottom. Between the two place a resistor (1.5k) an LED and an SCR (they give MCR104) in series. The diode and SCR both point down (anode at top). Normally the SCR os off. For the gate of the SCR place two resistors (1k each) in series with a n.o. switch between the red and green wires. Attach the gate between the two resistors.<p>When the button is pushed, the SCR triggers and creates a low impedance path through the 1.5k resistor and LED. Include another n.c. switch in series with the circuit to interrupt the current and reset the SCR. I can't guarantee this will be quiet but it shoud work.<p>A simpler way to do it is to mute the mouthpiece by inserting a toggle switch in series with the microphone. Use caution and an insulated switch, ring voltage on a phone can give a good shock.

[Externet]

Hi.
No misteries.
Connect a 200 ohm resistor across the telephone line and you will be able to hang up the handset and the line will hold.
After you pickup again, switch the resistor off the circuit.
Miguel