Handicraft for boys

by A. Frederick Collins

Fig. 105c. the spanker with electric solenoid control

The spanker, so called because it spanks the pup out of his kennel, is shown at [C]; it is simply a strip of wood ¹⁄₈ inch thick, 1 inch wide and 3¹⁄₂ inches long. Tack, or otherwise fix, a piece of tin to one side of it to form an electrical contact; cut a ³⁄₈ inch hole in the middle of it and then drive a brad in each edge near one end. The spanker sets in the slot in the floor and the brads rest in the grooves and serve as pivots.

A solenoid is merely an electromagnet with a loose iron core in it. Make a cardboard spool 1¹⁄₄ inches long and 1¹⁄₂ inches in diameter and have the hole in it ⁷⁄₁₆ inch in diameter; wind it full of No. 20 or 22 double cotton covered magnet wire and your solenoid is done. An iron bolt ³⁄₈ inch in diameter and 1¹⁄₄ inches long makes a good plunger, as the loose iron core is called. Slip it through the hole in the spanker and screw the solenoid to the inside of the back of the house as shown in the cross section drawing at [D].

Fig. 105d. cross section side view of the wireless pup ready for action

Make a contact plate of a strip of tin or sheet brass and screw this to the floor back of the spanker so that when the plunger is drawn into the solenoid and the spanker is back as far as it will go the plate will come in contact with the tin on the spanker. Put a stop in front of the spanker to prevent the latter from falling too far forward.

Fig. 105e. the front end view of the wireless pup house

Next get a strong, stiff piece of clock-spring, punch two holes in one end and screw it to the back of the house near the top, with the free end of the spring pressing out the spanker. Fasten by means of hangers, or otherwise, an ordinary telephone transmitter to the roof of the house as shown at [D]. Now make the front of the house and cut 4 × 5 opening in it for the pup to get in and out, and a hole 1¹⁄₂ inches in diameter, as shown at [E], so that when you put the front on, the hole will be directly over the mouthpiece of the transmitter.

Before putting on the front connect up the apparatus as shown at [D], that is, connect one of the wires of the transmitter to the contact plate; join the other wire of the transmitter to the battery; lead one of the wires of the solenoid to the tin on the spanker. When these connections are made the circuit will be complete if a battery is connected in and the spanker is pushed back. Now put on the front of the house and then make the pup.