How to make a Megaphone – Cardboard Megaphone

Learn how to make a  Megaphone  –  Cardboard Megaphone – excerpt from the book “The Scientific American Boy” by A. Russell Bond

A sheet of light cardboard 30 inches square was procured.
At the center of one edge a pin was stuck into the cardboard, then a piece of stout thread was looped over the pin and the two ends were knotted together just 5 inches from the pin.
Another knot was also made 29 inches from the pin.

Now, with a pencil hooked into the loop, and resting first against the inner knot and then against the outer one, two arcs were drawn on the paper, one of 5-inch radius and the other of 29-inch radius.

How to make a Megaphone

A line was now drawn from the pin to the point where the longer arc met the right hand edge of the paper, and a dotted line was drawn from the pin to a point 1-1/2 inches from the edge at the other end of the arc.

From a point 1 inch to the left of the pin we then drew a line to the left end of the arc.
With a scissors we cut the cardboard along the arcs and straight lines, all but the dotted line, leaving a piece of the shape shown in Fig. 55.
Layout of Megaphone
This piece was rolled into a cone with the right edge 59 lapped over the left edge and lying against the dotted line.

In this position it was held by means of several brass fasteners of the kind shown in Fig. 56.
Brass FastenerA mouthpiece was formed out of a block of wood in which a large hole had been drilled.

The block was then cut away until the walls were quite thin. The hole was reamed out at the top, as shown in Fig. 57, and the outer surface was tapered so that the small end of the megaphone would fit snugly on it.

Megaphone Mouthpiece
The SCIENTIFIC AMERICAN BOY OR The Camp at Willow Clump Island

Read more

Make a Rain Gauge – How to Make a Homemade R... Rain GaugeAn accurate rain gauge may be easily constructed from galvanized iron, as shown in the sketch herewith. The funnel, A, overlaps and rests on...
What is Fiber Optics? The baby in the picture hasn't been born yet. It is still lying inside its mother's womb.How could a photograph like this have been taken? The photogr...
WHO INVENTED THE PARACHUTE? Imagine if you find yourself into an empty space at the height of 4-5 miles above the Earth, and yet you have landed on the ground as if you jumped fr...
Toy Motor Boat – How to Make a Homemade Boat... The toy motor-boat shown in Figs. 48 and 49 is propelled by a tin propeller run by a rubber-band motor. A handful of rubber-bands will cost only a few...
Close Menu