Published:2011/8/23 22:12:00 Author:Amy
Rolf Badenhausen Construction The whole butterfly dipole antenna assembly, including transformer and coupling capacitor, is only the thickness of a ballpoint pen. It can be constructed on a single-sided piece of 1.5 mm thick epoxy resin printed circuit board. The mounting ... (View)
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Published:2011/8/23 21:59:00 Author:Amy
Rolf Badenhausen Butterfly dipole The real antenna impedance of a butterfly dipole is of the same order of magnitude as that of a hill-wave dipole. For such a full-wave dipole system a typical impedance would be between 240 Si and 300 Q, and in practice probably nearer 300 SI than 24012. In any case, matching is required to the nominal 75 Q input impedance of the antenn... (View)
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Published:2011/8/23 21:43:00 Author:Amy
Rolf Badenhausen Digital terrestrial television (DVB-T) is now available in many parts of the country. Of course, you need a DVB-T receiver and a (new) UHF TV antenna. If you don’t have a suitable antenna, the small indoor DIY alternative described here is a simple and economical solution. Terrestrial digi... (View)
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Published:2011/8/23 2:32:00 Author:Amy
N. S. Hori Sankar VU3NSH Setting up Give the PCB a final, thorough inspection for bad soldering, wrong components, etc., and resolve all problems before proceeding. Set all presets and trimmers to the centre of their travel. Apply power to the amplifier and check the various test voltages indicated in the circuit diagram. These voltages are typical and should not be taken to mean the ’law’ ’... (View)
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Published:2011/8/23 2:28:00 Author:Amy
N. S. Hori Sankar VU3NSH Construction The amplifier is built on the single-sided printed circuit board shown in Figure 2. The inductors in the design are all very simple to make, see the parts list for construction details. LI, 1.2 and L3, are wound on a 4.5-mm dia. drill or pencil. LI then needs to be stretched to a length of about 10 mm. You’ll find that a relatively large (View)
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Published:2011/8/23 2:17:00 Author:Amy
N. S. Hori Sankar VU3NSH Together with a good directional antenna this high performance two-stage antenna amplifier for the VHF FM broadcast band will enable you to capture far removed (DX) stations. Alternatively, it will drastically improve reception of FM signals you’ve come to accept as marginal and noisy in your area. FM broadcast(View)
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Published:2011/8/23 1:58:00 Author:Li xiao na
By Karel Walraven Get cracking We’ll now gel lo work, keeping the above information in mind. A little bit of searching on the Internet will quickly produce a number of free demo versions of nice printed circuit board layout software. At the end of the article we have included a few links lo get you started. When designing a PCB layout you start with the fixed constra... (View)
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Published:2011/8/23 1:26:00 Author:Li xiao na
By Karel Walraven What do most electronics engineers enjoy a lot? Designing printed circuit boards, of course! In an irregular series of articles we would like to familiarize you with this subject. We start as simple as possible and it will become more difficult as we progress. Feedback and requests to cover certain topics are encouraged and welcomed! When you’re just designing ... (View)
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Published:2011/8/22 23:56:00 Author:Amy
Gert Baars Construction The receiver is built on the printed circuit board shown in Figure 3. The board is single-sided and no problems are expected in the construction department as only regular-size components are used at the ’top’ side and a few SMD caps at the solder side. Also, there are no inductors to wind! (View)
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Published:2011/8/22 22:57:00 Author:Phyllis
Sensirion presented a new generation of mass flow sensors with patented CMOSens£ technology. The’ main advantage of the CMOSensl EcoLine was its very wide flow range (0-200 In/min with only one instrument) at an attractive price, especially for OEM applications. Thanks to the fusion of a thermal sensor element with the readout circ... (View)
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Published:2011/8/22 22:48:00 Author:Phyllis
This project has a modular structure, so it can easily be adapted to individual preferences. It consists of a general-purpose power supply board, an input selector board and the main circuit board, which holds the volume control IC and microcontroller. An LC display module, a keypad and an IR remote control unit complete the package. ... (View)
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Published:2011/8/22 22:47:00 Author:Li xiao na
By Herman Bulle Processing layer The function IntToStr (’integer to string’) converts a number into a line of text (text siring), and this text siring is assigned to Label I .Caption. This causes the result to be placed on the(View)
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Published:2011/8/22 22:43:00 Author:Amy
Gert Baars A dedicated receiver The detuning and resonance effects mentioned above take place at relatively small distances from the transmitter, say, two meters or less depending on TX power and antennas used. To be able to spot an active 13.56-MHz RFID transmitter from a greater distanc... (View)
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Published:2011/8/22 22:36:00 Author:Phyllis
Fast Components Limited, a new component supplier was targeting hobbyists with its brand new range of component kits. Co-founder Thomas Arundel said Electronic hobbyists have had a rough time of late. Leaded components are becoming more difficult to find, and incumbent suppliers are imposing ’small order’ or high shipping charges . As a result, the Fast Components team were offering a fresh and more economic way t... (View)
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Published:2011/8/22 22:27:00 Author:Amy
Gert Baars As we all know, checkout gates in highstreet stores will faithfully sound an alarm if you walk out with an item not ’cleared’ by checkout staff, i.e., paid for. This article describes a sensitive detector that will equally faithfully produce a sound in response to pulses picked up from an 1 3.56 MHz RFID ta... (View)
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Published:2011/8/22 22:26:00 Author:Phyllis
Microchip’s MPLAB® PM3 Universal Device Programmer was capable of supporting all of Microchip’s PIC® microcontrollers (MCUs) and dsPIC® digital signal controllers (DSCs). The PRO MATE® II universal programmer had been previously rated one of the leading programmers in CMP’s 2002 Embedded Market Study, and the MPLAB P... (View)
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Published:2011/8/22 22:08:00 Author:Phyllis
By Eberhard Haug If you’ve ever tried dimming a LED with a simple potentiometer, you know that the approach does not work very well. Just as with ordinary diodes, the voltage-current characteristic of LEDs is far from linear. The result — depending on the potentiometer setting the LED brightness will hardly chang... (View)
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Published:2011/8/22 22:02:00 Author:Phyllis
By Ton Giesbets Alignment After everything has been assembled and the wiring has been completed, you come to the moment when you switch on the amplifier for the first time. As a precautionary measure, connect 33 il, 5 W resistors in series with the power supply lines before switching on the amplifier, just in cas... (View)
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Published:2011/8/22 21:58:00 Author:Li xiao na
By Herman Bulle Processing layer If you press several digit buttons in succession, you want the digits to be placed in o row. This can be done by multiplying the previous number by ten and adding the current number to the result. Several operations are necessary to achieve this result. You have to store the first digit, read in the second digit, multiply the first number by ten ... (View)
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Published:2011/8/22 21:46:00 Author:Phyllis
By Ton Giesbets For each power supply terminal, insert the supply leads for the amplifier boards and indicator board together in the appropriate terminal blocks. Heavy wire with a cross-sectional area of 2.5 mm2 must be used for the amplifier boards, but thin flexible wire is adequate for the overdrive indicator board. Make the supply leads for the amplifier boards as short and direct as po... (View)
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