# abdelrazzac10

32
8Instructables55,797Views43CommentsThe city of Hassan Al-Rammah, Levantine TripoliJoined May 27th, 2016

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• The antenna is formed of a piece of wire. Any wire has a resistance that is proportional to its length. The longer the antenna is longer, the higher its resistance is. The resistance always tries to make the signal weaker.

The SN7413 NAND chip, 20 pF varicap (20 PF trimmer capacitor), a fixed 22 pF, a mic, and a 70 cm wire as an antenna

• abdelrazzac10 followed abdelrazzac10 and raja_9617 months ago
• Actually, the idea is very easy and straight forward and related to the natural frequency idea. Have you ever oscillate a rope? You should have seen that for the rope to oscillate in a very clear manner you have to lower and rise your hand with a given speed (Fig.1, a). This speed is called the natural frequency of the system formed of the rope and the node on the wall. Now if you get a shorter rope, you will find that you have to increase the frequency of your hand in order to keep the rope moving nicely (shorter ropes have higher natural frequency). If you move your hand with frequencies higher or lower than the natural frequency, you will note that the rope will move insanely and will stop after a while. This means that any frequency other than the natural frequency will generate a d...

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Actually, the idea is very easy and straight forward and related to the natural frequency idea. Have you ever oscillate a rope? You should have seen that for the rope to oscillate in a very clear manner you have to lower and rise your hand with a given speed (Fig.1, a). This speed is called the natural frequency of the system formed of the rope and the node on the wall. Now if you get a shorter rope, you will find that you have to increase the frequency of your hand in order to keep the rope moving nicely (shorter ropes have higher natural frequency). If you move your hand with frequencies higher or lower than the natural frequency, you will note that the rope will move insanely and will stop after a while. This means that any frequency other than the natural frequency will generate a damped motion that will stop the rope from oscillating. On the other hand, for a given hand frequency, we have only one rope length that ensures natural frequency.The same thing applies for antennae. For a given communication frequency (for example 100 MHz as in our FM transmitter), only one antenna length ensures the natural frequency of the antenna, thus an undamped oscillation at this antenna. With longer antenna length, the antenna material will generate a resistance for the signal resulting in weaker signal. For shorter antenna, the signal requires more length for one period to pass through the antenna, resulting in weaker transmission.Each antenna shape has a formula that should be used in order to find its length for a specific frequency. Yes, the antenna is just a piece of wire, but there are a lot of restrictions that should be taken into account while connecting an antenna.

• You cannot hot-glue the antenna, you have to solder it. Antennae are transducers that transform the electric signal into electromagnetic signal ( or RF signal) so it can travel in the space. They do NOT "boost" the signal! boosters are amplifiers. Second, an antenna can be as simple as a wire, but its length matters. The length of an antenna is defined by the wavelength it is going to be used with. Longer antenna will attenuate the signal, while shorter antenna will not give the RF signal time to be strong; both result in weaker performance. Kindly check the following links for the length of an antenna (you may have a quick search in the internet as well)http://www.csgnetwork.com/antennagenericfreqlencalc.htmlhttp://www.modelboatmayhem.co.uk/forum/index.php?topic=13093.0

• Well, I don;t think so. First, the signal generated by this circuit is too weak, and is not able to suppress station signals. Second, you have to know the frequency currently received by your neighbor's radio in order to suppress it efficiently. Third, what if your neighbor is listening to an AM station? You may use a spark transmitter to prevent their device from receiving radio signals but this is illegal to the best of my knowledge.

• abdelrazzac10's instructable DIY Drone Suitcase's weekly stats: 1 year ago
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• You are most welcome... Well, I don't have any idea about Makey Makey, but if you can program it to read from the computer using serial port and set/reset some digital pins so you can do the same thing (sure with its own programming). To the best of my knowledge, the MATLAB code can be used for both windows and MAC PCs

• abdelrazzac10 posted an instructable DIY Drone Suitcase1 year ago
• 1 year ago

Thank you very much for the important information! Good to know that Tesla was finally recognized.

• Well, I am not sure. Feedback-ing this chip will -most probably- produce an oscillation, but I don't know if the frequency of this oscillation will be 35 MHz. It is better to try. Please tell us if you succeed.

• It was not easy to find the chip, but it still available in the market. In the document I have, it says that the following ICs can be used as well:FLH361, HD7413, UPB213, TL7413, M63213, and MC7413. However, I can't guarantee this because I didn't test these ICs.

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