The battery (don't touch the wire with your hand) and then the electric fan will be fine.
(2) making pinhole camera
Method:
Pinhole camera
According to the principle of pinhole imaging, a pinhole imager can be made and a clear image can be seen on its screen. If you put a photosensitive film on the screen, you can take a clear picture and become a pinhole camera. However, this requires a "shutter" and a slot for loading negatives. In addition, the requirements for sealing are stricter than those for making ordinary pinhole imagers.
The structure of pinhole camera is shown in Figure10.6-L. The camera body is made of toilet paper and is divided into two parts: the front cover and the back cover.
manufacturing method
Draw it on the toilet paper according to the size of figures 10.6-2, 10.6-3, 10.6-4 (δ is the thickness of toilet paper), cut it along the solid line of each figure, and then gently carve it with a knife along the dotted line. Don't cut it, so as to fold the straight edge when bending. Then paint both sides of each block black.
Bend the cut front cover outer layer development drawing (Figure 10.6-2) by 90 degrees along the dotted line to form a five-sided paper box, and stick it with adhesive tape. Then stick a piece of 120 film black lining paper on one side with a round hole, and tie a small hole with a diameter of about 0.4 mm on the lining paper in the center of the round hole with a needle (the diameter of 12 sewing needle is about 0.4 mm). Then, as shown in figure 10.6- 1, stick a paper slot on the edge of the small hole and insert a hard paper strip in the paper slot, which can be used as a blind and keep the small hole clean.
Bend the cutting development diagram of the inner layer of the front cover (Figure 10.6-3) by 90 degrees along the dotted line, make it into a square cylinder, and attach the joint (the tongue is attached to the inside of the square cylinder). Then, fold the trapezoidal tongue at the notch end into a paper frame, align the notch with the reinforcing frame (Figure 10.6-4) and stick them together. Cut a paper frame with cardboard according to the size of the reinforced frame, align the gap and stick it on the reinforced frame, and stick this paper frame with the square tube outside with adhesive tape, so that a paper slot is formed between the reinforced frame and the rigid paper frame, and the negative can be loaded or taken out from the notched side. This gap is designed to facilitate the loading and unloading of negatives. After the inner layer is finished, the outer layer should be glued, that is, each trapezoid uvula at the other end of the square tube should be bent 90 degrees along the dotted line, coated with glue, aligned with the gap, and inserted into the outer layer. At the same time, a piece of toilet paper should be inserted between the inner layer and the outer layer of each face to ensure the same gap between the inner layer and the outer layer. After the front end of the inner layer is stuck to the surface with a round hole in the outer layer, the inserted toilet paper is pulled out, and the front cover is completed.
As for the manufacture of the back cover, except that the side width is 80+26 mm and there is no hole in the bottom surface, everything else is the same as the outer layer of the front cover. You can refer to the development diagram and corresponding dimensions of the outer layer of the front cover to make it.
Application mode
1. The pinhole camera has a fixed image distance of about 64 mm and a fixed aperture of 0.4 mm, so the aperture is also fixed. Experiments show that the pore size is about 160. When the brightness of the subject is different, it can only be adjusted by exposure time. Because the aperture number of a general camera is about 22, it is impossible to find out the exposure time of aperture 160, so it can be determined according to the ratio of exposure time equal to the square of aperture ratio (that is, t 1: t2 = (f 1: f2) 2). For example, when shooting a scene, the exposure time of aperture 16 is 1/30 seconds, then the exposure time of pinhole camera aperture 160 should be 3.3 seconds. The best exposure time should also be determined by experiments.
2. When taking photos with a pinhole camera, the framing method is shown in Figure 10.6-5. Stick one eye at the midpoint of one side and look out at the opposite ends. Then, the part sandwiched at this angle is the range to be taken. Moving the distance between the camera and the scene can change the image size.
3. Exposure: Take a good picture, calculate the exposure time, open the cardboard covering the small hole and close it until the scheduled exposure time.
4. Film loading and unloading: a single 60×60 mm 2 film is often difficult to buy, so it needs to be cut with a large film. Film loading, unloading and film cutting should be carried out in a dark room without light.
Matters needing attention
1. Be careful not to leak light when making.
2. Pinholes should be round and smooth.
3. Due to the long exposure time, it is advisable to shoot still life.
⑶ Materials: needles, candles, iron wires, cold water, transparent plastic bottles, iron cones and thin sticks.
Wrap the sewing needle with iron wire, then put it in the fire to burn red, and then put it in cold water to cool immediately. Remember, when dipping, you must make the needle face north and south, so that the needle can become a small magnetic needle. Also, be careful not to burn yourself!
Cut the bottle mouth of the plastic bottle, make a hole in the center of the bottom with an iron cone, then tie one end of the thin thread in the middle of a small magnetic needle, and then pass the thread through the hole. Invert the plastic bottle so that the small magnetic needle hangs in the middle of the bottle. Let the magnetic needle rest slowly. At this time, you will find that one end of the small magnetic needle points to the south and the other end points to the north.
⑷ Small craft product-fish tank water changer
1, production ideas: the life of goldfish is actually very long, but due to improper feeding, such as big moves in the process of changing water in fish tanks, the life of goldfish will become very short. How to minimize noise when changing water? I thought of using siphon principle to make a fish tank water changer.
2. Material: an empty beverage bottle, a 2-meter-long hose (with an inner diameter of about 7 mm) and all-purpose glue.
3. Manufacturing process: punch two holes (slightly smaller than the pipe) on the bottle cap of the beverage bottle, cut the flexible hose into two ends of 130cm and 70cm, insert the bottle cap 1cm respectively, glue the joint with universal glue, and tighten the bottle cap.
4. Usage: Insert one end of the long tube into the bottom of the fish tank, squeeze the bottle body and exhaust some air. At the same time, hold the nozzle of the short tube, then loosen the bottle to let water enter the bottle, and finally loosen the short tube, and the water in the fish tank will flow out.
Note: the height of the beverage bottle and the liquid level of the outlet must be lower than the liquid level of the fish tank.
5. Principle: Siphon principle
6. Advantages: It can minimize the interference to the fish, and you can suck out the dirty water mixed with fish excrement at the bottom of the fish tank without taking out the fish.