Homemade electric test pen

[Equipment] 1 neon bulb, 1 small spring, 1 small glass flat-bottomed tubular medicine bottle, 2 corks (or insulating rubber stoppers), 2 iron nails, 1 carbon resistor [0.25 watt, (2~5) kiloohms].

[Method]1. Carefully grind off the bottom of a small flat-bottomed glass bottle on a grinding wheel or rough cement floor to form a cylinder.

2． Remove the leads at both ends of the resistor, rub off the insulating paint on both ends, and put it into the cylinder with the small neon bulb and small spring.

3. Pass the two iron nails through the cork respectively, cover both ends of the cylinder and keep the nail caps inside the cylinder. Make good contact with the spring and neon bulb respectively. The simple electric test pen is completed.

4. How to use: Use the thumb and index finger of your right hand to hold the glass tube so that the nail tip at the back of the tube is against the palm of your hand. The nail tip in front is in contact with the bare wire to be tested or the copper sheet in the socket hole. If neon If the bulb glows, the conductor under test is a live wire.

How to make innovative small inventions 1. Homemade badminton

Materials to prepare: one empty drink bottle, two foam fruit net sets, one rubber band, and one glass marble.

Production process:

1. Take a 250ml empty beverage bottle and cut off the upper part of the bottle;

2. Cut off the Divide the portion into 8 parts, use scissors to cut to the neck of the bottle, and then cut each part into a petal shape of the same size;

3. Put the foam fruit net sleeve on the outside of the bottle and use a rubber band Fix it at the mouth of the bottle;

4. Wrap another foam fruit net cover around a glass marble, insert it into the mouth of the bottle, plug it tightly and expose about 1 cm;

5. Cut half of a table tennis ball, place the bottom of the hemisphere on the mouth of the bottle, cut the four sides into whiskers, cover the mouth of the bottle and secure it with a rubber band.

6. After beautification and modification, a homemade badminton is completed. Hit it with a badminton racket and see what the effect is?

2. Homemade soap paper

Materials and tools:

White paper with good hygroscopicity, small pieces of soap, a writing brush and disposable drinks Can.

Preparation method:

First chop the soap and put it in a jar. Fill it with an appropriate amount of water and heat the cup on the stove. When the soap melts, cut out the white paper. It is about the size of a matchbox. Apply soap solution one by one, then take it out and dry it in the shade to become soap paper.

3. Homemade hot air balloon

1. First, we cut out 6 to 8 leaf-shaped pieces of paper from soft paper.

2. Fold them in half and glue their edges together to make a balloon.

3. Use tape to stick the four connecting wires to the bottom of the balloon. Use plasticine to secure the other end of the string to the table.

4. Try to adjust the speed of the hair dryer as slowly as possible. Aim the blower outlet upwards at the bottom opening and turn on the switch. The balloon will slowly grow larger, tighten the string, and lift off the table.

4. Homemade flashlight

The specific production method is: remove the lid from one end of a waste can (such as Lulu beverage can), and use a round-headed hammer to dent the other end. Use thick corrugated cardboard to roll up two AA batteries, with the positive pole facing up and the negative pole facing down, and put them into the can. Find a suitable plastic lid (such as the magic large rolled box lid that can be buckled on the Lulu beverage can), and dig a small circular hole in the center of the lid, the size of the hole is appropriate for the light bulb to be inserted tightly. Insert the bulb base into the small hole. Take a piece of hunting wire, peel off both ends of the wire, wrap one end around the lamp holder, and poke a small hole through the side of the plastic cover with the other end. Place the plastic lid on the can. Check whether the bulb and battery are in close contact. The disposable flashlight is ready here. When in use, use your thumb to press the wire coming out of the side wall onto the paint-free weld of the can, and the flashlight will shine. If your thumb leaves the wire and jumps up, the flashlight will go out. It is very convenient to use.

5. Homemade solar cooker

Find a concave reflective bowl on a large flashlight, and use rigid foam plastic or wood to cut a cylinder about 4 cm long and 1 in diameter. It should just fit tightly into the round hole of the reflective bowl.

Drill a thin hole transversely at one end of the cylinder, insert an iron wire with a diameter equivalent to the diameter of the hole, and then bend the two ends of the exposed iron wire at 90°, leaving 5 cm on each side. Insert the cylinder into the round hole of the reflective bowl, and then insert both ends of the wire into a piece of foam plastic or wooden base. Sharpen both ends of a thin bamboo stick, insert one end into the cylinder in the center of the reflective bowl, and insert a small piece of potato into the other end. Place the device in the sun, with the reflective bowl facing the sun, and then patiently adjust the length of the bamboo stick so that the inserted potato is exactly at the focus of the light. Before long, the potatoes will be roasted by the sun and become fragrant.

6. Homemade colored candles

Materials: colored crayons, wax

Preparation method:

1. Find a discarded canned beverage barrel (such as a 1.25-liter Coke bottle), neatly cut off the lid, and chip the wax into the barrel.

2． Put the bucket into hot water and stir the wax inside to melt it all. It's best to use boiling water. However, you need to ask your parents for help or perform this step under their supervision.

3. Pour the melted liquid into a nice-shaped container (such as a heart-shaped frame with small pieces of chocolate). Don't pour too much. As for the reason, read on. Of course, you first need to put the candle wick string in the container.

4. After the original wax cooled down, Ah poured the melted colored crayon liquid into it according to the method of divination (the colored crayons came in handy at this time). In this way, add different colors of wax layer by layer, and a beautiful candle is made.

7. Homemade wall-hanging flower basket

Materials and tools: two Sprite bottles, glue, carving knife, scissors.

Production method:

1. Remove the green bottom cover of a Sprite bottle, cut it into a lotus shape, flip it down and glue it to the bottle body to form a base.

2． Cut a 2cm wide green ring from the green bottom cover and still put it on the bottle.

3. Remove the neck of the bottle and cut a wide strip 13cm long and 8cm wide, and several narrow strips 3cm wide.

4. Use a carving knife to carve patterns on the 3 cm narrow strips as shown in Figure 3, then fold these narrow strips outwards and insert them into the green ring from bottom to top.

5. Take another beverage bottle, use the bottle body, and use scissors to cut out 6 17 cm long capsule leaves.

6． Nail the flower basket to the wall, insert leaves and flowers, and the wall-mounted flower basket is ready.

8. Homemade cockroach catching box

Take a piece of cardboard of 220×150 (mm).

The most important part of the capture box is the capture surface. Take a piece of plastic film, cut it to the same size as the bottom of the box, apply adhesive and spread it on the bottom of the box. The key to whether cockroaches can be caught lies in the adhesive. The adhesive has two functions: one is to introduce the cockroach into the box, and the other is to stick it firmly to the catching surface. Preparation of attractants: Mix 40% meat powder, 50% flour, and 10% bean cake. The total amount is about 20 grams. Mix well and set aside. The adhesive is a mixture of 20 grams of rosin and 10 grams of rapeseed oil. After heating to a gelatinous state, mix the attractant and adhesive and stir evenly to make an adhesive.

Evenly apply the above-mentioned paste on the catching surface lined with plastic film, then fold it inward according to the originally drawn dotted line, and finally insert the tongue piece b into the notch a. Inside.

Due to the non-drying properties of the rosin and rapeseed oil mixture, the bait can be kept sticky for up to a week. Place the trap box in a place where cockroaches are infested. Because the box is dark and contains the bait that cockroaches like, cockroaches will crawl into the box to compete for the bait and get stuck to it. After it is full, the carton can be flattened and discarded, or the plastic film can be removed and the plastic film coated with bait can be replaced so that the box can be reused.

If the size of the trap box is enlarged and the composition of the adhesive is slightly adjusted, the coating can be thickened to make a paper mousetrap.

Matchbox Microscope

This is a simple matchbox microscope with a high magnification and single lens. It is very convenient to carry and use.

The materials for making it are also easy to find: one matchbox outer shell, one small glass bead (you can use the small glass bead at the front of the light-concentrating bead to replace it), two inner matchboxes, a small piece of glass, and a glass mirror. A small piece, tape and glue.

The production process is also very simple. First, hollow out the inner box of a matchbox, cut off the horizontal rails at one end, and poke a small hole in the middle of the other end that is just the right size for glass beads. Put the glass beads in. After entering, cover it with a piece of white paper with a small hole in the center that is equal to the diameter of the glass bead. The first step is completed. In the second step, make a small elongated hole of about one centimeter in another inner match box facing the lens, stick a piece of glass on the hole, and stick it firmly with tape, so that the stage is completed. The lens holder only needs to cut a square hole on one side of the trademark to serve as the entrance. The fourth and final step is to install the reflector: stick tape on the back of the mirror, fold the tape back at 90 degrees, and stick it to the lower end of the inner box of the matchbox to tilt the mirror.

When using, place the object to be observed on the glass on the stage, then insert the lens holder so that the small window faces the light source. By adjusting the height, you can see the enlarged object clearly.