Matt circuit

This alarm plays your prerecorded voice message. It is built around the readily available quartz clock. Take the buzzer out of the quartz clock and connect its positive terminal to pin 1 and negative terminal to pin 2 of optocoupler IC MCT2E (IC2). Pin 4 of IC2 is grounded and pin 5 is connected to trigger pin 2 of monostable multivibrator IC 555 (IC3) as shown in Fig. 2. Fig. 1: Voice recording circuit Fig. 1 shows the circuit for recording your voice message. When you press switch S2, it plays the meassage. The control circuit shown in Fig. 2 avoids the need for pressing switch S2 and thereby sounding the voice alarm automatically at the preset time. Connect points A and B of the recording circuit to the corresponding points A and B of the control circuit. After making the connections, press record switch S1 to record your 6-second voice message through condenser microphone. Set the desired alarm time in quartz clock. At the time of alarm, buzzer terminals provide voltage to the inte...

45 second message recording without tapes or discs. Use it for phone messages, a voice memo pad, you name it! When you need to record voice messages with the highest possible reliability, there’s no substitute for a solid-state voice recorder chip. There are no moving parts at all, so there are no tapes or belts to break, no heads to clog up with gunk, no motors to burn out and no bearings to jam. Instead, there’s just a memory chip to store and replay the message electronically, any number of times. Because it’s solid-state, the message(s) can be played back instantly – there’s no tape to rewind. Small wonder that most telephone answering machines changed over to this kind of recording years ago. We’ve described solid-state voice recorder projects in the past and they’ve been very popular. However, the special chips they used eventually became hard to get and so these projects eventually fell by the wayside. This situation recently changed for the better again, when Jaycar Electronics...