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1、(C) SAFETY FIRST DO NOT attempt to use an electrical wall outlet, or connect to any electrical appliance to ground your radio. Use a cold water tap, or “ground stake”. DO NOT mount your antenna near to, or over the top of, electrical power lines of any type. If your antenna wire should break it coul
2、d contact the live power and a severe ELECTRICAL SHOCK and possibly DEATH could occur. DO NOT leave your antenna cou- pled to the radio when it is not used, as it is an attraction to LIGHTING STRIKES and/or violent electrical STAT- IC DISCHARGE. Place the free end of the antenna OUTSIDE and clear of
3、 the building or connect it direct to earth. DO NOT operate the radio during the approach of, or during an electrical storm . CRYSTAL RADIO KIT TM 8893 (A) List of Parts provided in the CRYSTAL RADIO SET 1.8 Brass furniture thumbtacks 2.70 of Copper magnet wire #30 3.1 Large paper clip 4.1 - 470 pF
4、disc capacitor 5.1 - 0.01 F disc capacitor 6.1 - Germanium diode 7.1 - Crystal earphone with wires 8.2 - Alligator clips with wires 9.1 - PLMCRS1 instructions Parts you need to obtain: 1 cardboard tube (toilet papertube) 1 board (wood, 71/2” x 5”) sticky tape (to hold coil you make) quick drying var
5、nish, nail polish, or clear radio cement Tools Needed: needlenose pliers a small hammer wire cutters (B) Project Description The complete CRYSTAL RADIO SET KIT #8893 includes everything you need except for the wood baseboard, the cardboard tube from a toilet paper roll and varnish, nail polish, or c
6、lear radio cement to paint the coil. This little project is a sure interest grabber with students of electronics of any age! It does not require a great amount of skill, but a little application will produce a good basic radio receiver. Construction is fairly simple. This radio DOES NOT require batt
7、eries to oper- ate, using simple electrical principles to power itself. This circuit is for the simplest radio receiver that can be practically con- structed - yet it is the basic building block of more highly sophisticated and complex units. GIBSON TECH ED, INC. 1216 S 1580 W OREM, UT 84058 1-800-4
8、22-1100 GIBSON TECH ED, INC. 1216 S 1580 W OREM, UT 84058 1-800-422-1100 Copyright 1996 PracTrak, Inc.2 L1 C1 C2 D1 E1 (G) Complete Parts List A (9cm x 13cm) or (7.5in. x 5in.) block of Pine wood, or chipboard.(not included in kit) 8 BRASS flathead thumb tacks. 2 Alligator Clips, one for antenna, on
9、e for ground. A discarded cardboard roll from a toi- let paper roll.(not included in kit) L1 - 70 of 30 Gauge Magnet wire for approximately 145 turns around the cardboard roll. A large wire paper clip. 300mm length bare copper. C1 - A 470 Picofarad ceramic disc capacitor. C2 - A 0.01 Microfarad cera
10、mic disc Capacitor. D1 - A Germanium Point Contact Diode Type OA90. E1 - A CRYSTAL earphone (H) Schematic Diagram (D) Operating instructions In order for the radio set to work you will have to connect it to an ANTENNA and a GROUND. In some locations an antenna may not be necessary, but a good ground
11、 connection is very impor- tant. A cold water pipe is usually the best to use, or you can put down an “earth stake“ and connect to it. The best antenna for this radio can simply be a really long wire, mounted as high as possible. Good results can also be produced by using metal bed spring frames or
12、a fence. Be creative! Crystal radios are not very selective, nor very sensitive. Several stations may be heard at once, many of them equally as strong as the others. A long antenna (30+ meters) will improve the strength of some stations, helping you tune them in a little more easily. Operation is th
13、at simple. (E) Theory of Operation The crystal radio works by creating an oscillator with the coil and C1. The placement of the wiper along the coil varies the amount of inductance in par- allel with the capacitor. This tunes our radio by determining the oscillating fre- quency. The signal is then r
14、ectified by the diode and smoothed out by C2. The resulting signal causes a thin ceramic crystal in the earphone to vibrate creat- ing the sound that we hear. (F) Reading Comprehension 1. The wiper varies the amount of_in parallel with the capacitor. 2. The signal is_by the diode. 3. The crystal _ v
15、ibrates to create sound. Antenna Ground 3 Step 7 (CoiL) Attach the Coil you just made to the board as indicated by the pattern, placing the tacks through the tabs of the tube. (You may need a small hammer to tap the tacks down tightly. ) Do Not hammer any other tacks down into the board until all th
16、e other parts have been properly positioned. Step 8 (Wiper) Place the wiper in position on the board and rest it against the coil. From this you can see where the coil will need to be scraped free of insulation. (This area on the coil is shown as a white stripe on the Pictorial Diagram page 4.) The
17、enamel insulation and varnish you coated the coil with can be removed using a fine cut file or fine grit emery papertaking care not to displace or break any of the coil turns. Make bare an area about 10-15 mm wide, across the face of the coil. The coat- ing also needs to be removed from the leads, t
18、hen they can be wrapped around the appropriate tacks “A” and “F”. Step 9 With the straightened paper clip acting as a WIPER, the coil will be a VARIABLE INDUC- TOR (See the Pictorial Diagram page 4). The free end of the wiper is bent at an angle so that it will wipe along the bare wires of the induc
19、tor when secured in place on the baseboard. Step 10 Identify the Diode (D1) with the black stripes at the end corresponding to the line shown on the schematic symbol. Place it as shown in the schematic on the board in the correct position between tacks “B” and “C”. Step 11 Identify the capacitors (C
20、1, C2) and place them in position. C1 goes between tacks “B” and “D”, and C2 goes between “C” and “E”. Step 12 Take one of the alligator clip leads and wrap the end of the wire around tack “A”. Wrap the end of the other alligator clip lead around tack “F”. Make sure that you ham- mer these tacks dow
21、n securely to prevent the alligator clip wires from pulling away from the tack causing loss of contact. Step 13 Take bare copper wire and connect tacks “D”, “E”, and “F”. Step 14 When all of the components are arranged as desired, the tacks can be hammered into place. Now your radio is complete. Hap
22、py Listening! Step 5 (Coil) (See Fig. 3) Make a small hole with a tack, 1cm in from both ends of the tube. Push 15cm of the wire through from the outside of the tube to the inside and wrap the wire tail twice around the tab at one end, this prevents the wire from slipping as you wind. Starting 1cm f
23、rom the edge of the tube firmly wind on as many turns as will fit between the two holes (approximately 145 turns,) ensuring each turn is straight and tight together no gaps! (If you need to stop winding for any reasonuse a small length of sticky tape to secure the coils.) When you reach tab #2, trim
24、 off the wire to 15cm and wrap it twice around the tab. A coat of quick drying varnish or nail polish will secure the coil loops permanently. Coat the cardboard tube at the same time and place the assembly aside to dry. Step 6 Straighten out a paper clip with pliers and a hammer. In one end make an
25、open loop 5mm in diameter. This paper clip will be used as a wiper on the coil. (See the Pictorial Diagram page 4). All the compo- nents and wires are secured with furniture tacks no soldering is required. For a better connection to the tacks make small loops at the ends of the wire leads on the cap
26、acitors and diode and the copper wire which joins the various parts of the circuit together. (I) Assembly Instructions Tools needed: A small hammer, a pair of wire cutters and a pair of needlenose pliers are all the tools required. A roll of household sticky tape is handy for holding wire in place a
27、s you wind the coil. Step 1 (Wood Project Board) Cut a piece of wood to 5” x 7 1/2” x 1/2” Step 2 (Layout Pattern) Cut out the Layout Pattern and glue it to the wood. Step 3 (Coil) Prepare the tube to wind the coil. Measure and cut a 7cm length of the tube. Draw a line all the way around the tube to
28、 use as a guide while cutting. Draw two more lines 1cm in from eather end. Cut tabs on both ends exactly across from each other then fold them in, out of the way for cutting off the extra tube length. (See Fig. 1) Step 4 (Coil) Using scissors, cut the extra length from the tube. Do not cut the tabs
29、off as they will be used to hold the tube to your wood project board. The easiest way to cut the tube straight is by placing the flat of the scissors against the folded tab and following your line around as shown in Fig. 2. Small hole 1cm from edge of tube 15cm tail of wire wrap wire twice around ta
30、b Tab Flat side Beveled side Scissors 5mm Loop Wires must be side-by-side like this No crossed wires No spaces Tab Tab 5cm 1cm 1cm 7cm Fig. 1 Fig. 6 Fig. 7 Fig. 3 Fig. 4 Fig. 2 Layout Pattern Glue Wood 5 x 7.5 in. Project Board Diode D1 Crystal Radio Set Built by: A BC DEF Coil Copyright 1996 PracTr
31、ak, Inc. 4 To Ground To Antenna D1 Diode L1 C1 470 C2 .01 Capacitors Alligator Clip Alligator Clip Wiper Crystal Earphone Wire from coil Sanded strip 10- 15mm wide Wire from coil Bare Wire Project Board (K) Pictorial Diagram (J) Layout Pattern (above, exact size) Cut out the layout pattern and place it on your board. Build your radio on top of it. = Thumb Tacks Cut on dotted line. This and other Kits are available on the internet at : (L) Web Address
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