Pencil Alarm

Project Number: 81

OBJECTIVE: To draw an alarm activator.

Description: Build the circuit shown and connect the two jumpers to it, leave the loose ends of the jumpers unconnected for now. There is one more part you need and you are going to draw it. Take a pencil (No. 2 lead is best but other types will also work). SHARPEN IT, and fill in the shape below. You will get better results if you place a hard, flat surface directly beneath this page while you are drawing. Press hard (but don't rip the paper), and fill in the shape several times to be sure you have a thick, even layer of pencil lead.

Turn on the slide switch (S1) and take the loose ends of the jumpers, press them to the shape and move them around over the drawing. If you don't hear any sound then move the ends closer together and move over the drawing, add another layer of pencil lead, or put a drop of water on the jumper ends to get better contact.