3 in 1 pencil holder

i1 96 3 in 1 pencil holder There are many different types of pen cum pencil cum paperclip etc. holders available nowadays. They come in all shapes, sizes and colours, but the ma- jority of them tend to become rather boring after a d to 4 2 4 lb 41 4 tab le W. Gietmann while. The circuit described here is intende nc- other fu remedy this situation by providing two tions at the same time. These are a telephone timer and extension amplifier. The circuit diagram of the device is shown in fig- ure 1. The extension amplifier consists of an readily available suction microphone and an integrated audio amplifier (LM 386). The output of this IC loud- can be fed directly to an eight ohm (1 W) speaker. The timer section consists of a 555 timer IC connec- ted as an astable multivibrator with a frequency of 37 Hz. This signal is then divided by 16384 in IC3 to provide an output pulse every 71/2 minutes. This output turns on transistor T1, which in turn drives the piezoelectric buzzer. This sect...