![]() ![]() But the rest have a good chance of being usable even after 40 years. In older equipment you have to be careful with electrolytic capacitors and some power resistors due to changing values over time. These radios have tons of useful parts like transistors, resistors, crystals, IC's, and ceramic capacitors. I got lucky and found three 1970's and 1980's vintage CB radios that weren't working. But in my area I have been successful obtaining recyclable equipment made in the 80's that have lots of components I can reuse. A lot of modern electronic devices aren't good candidates for part recycling due to the size of the components. A lot of people will gladly donate unwanted radios, stereos, CD radios, and other devices to someone like me that wants to learn and is willing to come get them. ![]() If this fails to work, you may need to rebuild the circuit from scratch.I enjoy salvaging electronic parts from discarded equipment. Adjust connections until you can hear audio when power is supplied.The solution is to connect the jumpers in the same group of 5 holes of the same row, or to bridge the two rows with a small jumper wire at the middle of the rows. If the jumper wires are connected such that one is in the left side of a row and one is in the right side of a row, the radio will not work. In this radio, there is only one voltage is used. X Research source This is used when there are 2 different voltages in a circuit. Some breadboards have the top and bottom rows split into a left side and a right side.The rows at the top and bottom on the breadboard are separate, make sure that the holes where the jumper wires are plugged in belong to the same row, not adjacent rows.The adjacent columns are not connected, therefore that component will not be connected to the others and may even be connected to the wrong item. Inspect your connections on the breadboard to see if you have not connected a component in an adjacent column.Sometimes you may have thought that you’ve pushed the lead all the way in to the board without it actually making a good connection.All leads need to be firmly inserted into holes, and each part of the circuit needs to be hooked up in the right fashion for it to operate. Circuits can be touchy, and many require troubleshooting, especially if this is the first circuit you’ve ever built. This layout avoids crossing the jumper wires and possibly causing a short circuit. The op-amp is now oriented so that the top and bottom row match the polarity of the V+ and V- pins, when they are connected to the battery later.It is important not to reverse the polarity to the op-amp as it will destroy it.From the leg opposite 4, moving right to left: 5, 6, 7, 8. Confirm the numbering of the legs of the amplifier after installation is as follows: on the bottom row, moving left to right: 1, 2, 3, 4.The pins are numbered consecutively from 1 starting on the bottom row and continue counter-clockwise on the other side of the device. Sometimes in addition to, or instead of, the divot, pin 1 has a circular depression or dot above it. To identify the pins, place the divot the left of you, pin 1 is the first pin on the left of the bottom row. This will allow an uncluttered layout, with the input (the antenna and tuning capacitor) on one side of the breadboard and the output (the speaker) on the opposite side. ![]() Place your op-amp (with the divot on the left) centrally on the board so that four pins are on one side of the trough and four are on the other. Most breadboards have a long trough running across the middle, separating the board into two equal halves.The printed logo, letters and numbers on the device are the right way up when viewed this way. Hold the op-amp so that the divot or dot is on your left. If there is no divot, there should be a small circular depression or dot on one corner. Notice that the op-amp has a small semi-circular divot on one edge, which is used to orient it properly. Wire strippers (or a similar item, like sharp scissors or a knife).Toilet paper tube, or small, non-conductive cylinder, 1.75–2 inches (44–51 mm) in diameter (glass bottle, cardboard/plastic tube, etc.).Operational amplifier, type 741 or equivalent (also called an op-amp X Research source x1).50–100 ft (15–30 m) insulated wire (any color for the antenna).22uF electrolytic capacitor, (10v or higher) (x1).200pF variable tuning capacitor (160pF will do.45–60 feet (14–18 m) of 26 AWG (0.4 mm) enamelled wire (for the inductor).15–20 inches (38–51 cm) of black insulated wire.15–20 inches (38–51 cm) of red insulated wire.These can be bought at most hardware stores, home centers, and electronics stores. You likely already have many of the parts you’ll need for this project, excluding some of the electrical components. ![]()
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