Group items tagged

Crystal quartz oscillator circuit Another great quartz crystal oscillator schematic with bb139, a 2-nd harmonic quartz crystal and one BF214 transistor. So, the Q quartz is half of the desired transmitter frequency, L1 has 24 turns, 0.08mm Ø built on a 455kHz carcase. L2 has 8-9 turns / 0.8mm Ø / 5mm Ø. This quartz oscillator circuit has a great frequency stability, I’ve build it. Crystal quartz circuit components R1 = 10K R2 = 100

16f84 weeder frequency counter

Circuit audio power amplifier using integrated lm4782 overtureTM for three channels of 25W with mute and stand-by LM4782 is audio amplifier of three channels capable to supply 25W of potency for channel. LM4782 uses the system of protection of National Self Peak Instantaneous Temperature (˚Ke) (SPiKeTM). Spike protects the exit of the lm4782 of on tension on load, short of the source for gnd, temperature protection and picks instantaneous of temperature. Each amplifier of the lm4782 has a mute circuit and internal stand-by, that can be controlled by logic it expresses. LM4782 can be configured to be used in bridge or in parallel way without complications, it exists several ways to use integrated him. To know more on spike it seeks for AN-898 in the site national.com . Description of the operation of the circuit of the amplifier with lm4782 The circuit described here it is treated of the application suggested by the national semiconductors for an amplifier of potency of three channels with having integrated lm4782. To determine the heat-sink to be used it sees the datasheet of the lm4782. In the way stand-by the drain of current of the source VCC is less than 30µA for all amplifiers and chain drained of the source VEE is typically of 8mA. Bypassing Capacitors To eliminate possible oscillations or instability in low frequency high frequency either is used a capacitor electrolytic or of tantalum to absorb variations in low frequency and a ceramic capacitor to prevent feedback in discharges frequencies. those components are placed in the power lines. Filter high raisin The combination of it Laughs with ci it creates a filter high raisin. The frequency answer is determined by those two components. The point of -3dB can be found using the equation below: fi=1/(2ÀRiCi) (Hz) If a capacitor of blockade dc be used, there is another filter it passes discharge servant with the combination of Cin and Rin. When great values of Rin are used it can happen oscillations in the exit. To determine the type of the heat-sink and other assembly configurations it sees the datasheet of the lm4782. Source for the circuit That proposed circuit requests a symmetrical source of +-25volts that is capable of ?¤ “teão is necessary that is regulated. Just use a good transformer, rectificators and great capacitors of filter of at least 10000µF. The transformer uses transformer torodal preferably, they exist virtual stores that sell transformers and they dispatch for the whole brazil. Schematic of the circuit of the potent amplifier with lm4782 Orijinal görüntüsünü görmek için buraya tıklayın. 524x566 px. Printed circuit board (couple face) side of the it welds suggested by the national for assembly of the potent amplifier of three channels Circuit board (couple face) printed side of the components suggested by the national for assembly of the amplifier Assembly of the components of the amplifier in the board silkscreen of the board of the amplifier It lists of material for assembly of the amplifier Name value tolerance type /description RIN1,RIN2,RIN3 33kP6; 5% 1/4 watt RB1,RB2,RB3 1kP6; 1% 1/4 watt RF1,RF2,RF3 20kP6; 1% 1/4 watt Ri1,Ri2,Ri3 1kP6; 1% 1/4 watt RSN1,RSN2,RSN3 4.7P6; 5% 2 watt ID 2.7P6; 5% 1/4 watt RV 5.1kP6; 5% 1/4 watt CIN1,CIN2,CIN3 1µF 10% Film metallic polyester CN1,CN2,CN3 15pF 20% Ceramic Ci1,Ci2,Ci3 68µF 20% Ceramic Radial / 35V CSN1,CSN2,CSN3 0.1µF 20% Ceramic CV 0.1µF 20% Ceramic CS1,CS2 0.1µF 20% Ceramic CS3,CS4 10µF 20% Radial Ceramic /50V CS5,CS6 2,200µF 20% Ceramic Radial / 50V S1,S2 Key SPDT (on-on) J1,J2,J3 PCB Montage RCA Jack J5,J7,J9,J11 PCB Banana Jack – Black J4,J6,J8,J10,J12 PCB Banana Jack – Red VZD 5.1V Zener Diode 1W U1 LM4782 TO-220 For more information to do download of the datasheet of the lm4782

This is circuit 13.8V, 40A Switching Power Supply,It is high current power supply switching regulator.And Nice Circuit for power user. This article was originally published (in a slightly modified form) in the QST magazine, December 1998 and January 1999, and in the Radio Amateur's Handbook, 1999. Visit the American Radio Relay League for information on these publications, and a world of ham radio related things! Design decisions There are several different topologies for switchers in common use, and the first decision a designer must take is which of them to consider. Among the factors affecting the decision are the power level, the number of outputs needed, the range of input voltage to be accepted, the desired tradeoff between complexity, quality and cost, and many more. For this power supply I decided to use the half bridge forward converter design. This topology connects the power transformer to a bridge formed by two power transistors and two capacitors. It is reasonably simple, puts relatively low stress on the power transistors, and makes efficient use of the transformer's magnetic capabilities.The second basic decision is which switching frequency to use. The present trend is to use ever higher frequencies. But by doing so it becomes more difficult to filter out the RF noise inevitably generated by the switching. So I decided to stay at a low switching frequency of only 25 kHz for the full cycle, which due to the frequency doubling effect of the rectifiers results in 50 kHz on the output filter. For the main switching elements, bipolar transistors or MOSFETs can be used. Bipolars have lower conduction losses, while MOSFETs switch faster. As in this design I wanted to keep the RF noise at an absolute minimum, very fast switching was not desired, so I used bipolar transistors. But these tend to become too slow if the driving is heavier than necessary. So, if the transistors have to switch at varying current levels, the drive to them must also be varied. This is called proportional driving, and is used in this project. The half bridge converter is best controlled by pulse width modulation. There are several ICs available for this exact purpose. I chose the 3524, which is very simple to use and easy to find. Any 3524 will do the job. It can be an LM3524, SG3524, etc. This basically ends the big decisions. From now on, designing the circuit is a matter of calculating proper values for everything.

If you are interested to build TV transmitter for your electronic project this Advanced TV Transmitter With Sound designed by Tetsuo Kogawa could be good idea for you. TV transmitter consists of of the two sections: video transmitter and audio amplifying. Both of them actually is transmitters. The main one generates video carrier while the smaller one generates the exact 4.5 (5.5 in some countries) MHz FM audio carrier. When it is supplied to the main section, the combination generates the audio carrier that is the total of the video frequency plus 4.5 MHz (this is the same in the US but different in other countries: 3.5 in the UK, 5.0 in Italy, 5.5 in Australia and so on: see the channel plans). The Audio section (1)Coil: The most difficult point is the coil. You can use any type of coil as long as it fits the inductance. But the size of coil for 4.5 MHz is quite large if you use usual type of coils. Here I will use Ferrite Troidal core that is made by Amidon Associates. Wind 0.2 ECW (enamel-coated wire) around the "FT-50-43" (Amidon) in 24 turns. (2)Transistor: You can use popular ones such as 2SC2001, 2SC1815, 2SC1907, etc. But you must keep the pins (E, C, B). How to adjust: Connecting the prove of the frequency counter at "#to the audio-in". Then adjust "Trimer cap. (80PF)" as the frequency counter shows exactly 4.5MHz. Sometimes, you have to add some capacitors (depending 100-1000PF) at the "E(mitter)" position of the transistor in order to adjust the frequency.

Switching regu*lators are available is different circuit configurations in*cluding the flyback, feed-forward, push-pull, and non-iso*lated single-ended or single-polarity types. Also, the switching regulators can operate in any of three modes – step-down, step-up, or polarity inverting. LM 2575 series of regulators developed by National Semiconductor are monolithic IC’s that provide the active functions for step-down (back) switching regulator, capable of driving a1A load with excellent line and load regulation. These devices are available in fixed output voltages of 3.3V, 5V, 12V, 15V and an adjustable output version. Requiring a minimum number of external components, these regulators are simple to use and include internal frequency compensation and a fixed-frequency oscillator. LM 2575 series offers a high-efficiency replacement for popular 3-terminal linear regulators. It substantially reduces the size of the heat sink, and in many cases no heat sink is required. Fixed output voltage version is illustrated in figure. The National Semiconductor LM 1577/LM 2577 are monolithic ICs that provide all of the power and control functions for step-up (boost), fly back, and forward converter switching regulators. The device is available in three different output voltage versions: 12 V, 15 V and adjustable.

This HD TV UHF wideband amplifier(Ultra High Frequency amplifier) has a total gain of 10 to 15 dB in the 400 – 850 MHz domain frequency so it can be used where the tv signal is weak. For this UHF antenna tv amplifier to work correctly you need to cut the components pins as short as possible. C1, C2, C6, C7 are SMD type ( surface mounted ). This antenna tv amplifier or uhf wideband amplifier need to be build inside of a metal box and then connected close to the tv antenna. Prototype pictures (Prototip resimler) Antenna HD TV UHF band amplifier circuit schematic (Anten HD TV UHF bandındaki amplifikatör devre şeması) PCB layout for Wideband HD TV UHF Antenna TV Amplifier Circuit using transistor 2sc3358 (Baskı Devresi) The power supply is a simple 12V stabilized source. The antenna tv amplifier can be connected directly to the power supply thru coaxial cable of the tv antenna but you need a 10 – 100uH coil on the alimentation line. The tv set will be connected to the uhf amplifier thru a small coupling capacitor. Adjusting is easy, just bring the P1 to the middle and then adjust it untill you obtain the best tv image quality. Digital Tv antenna UHF amplifier components (Devrede kullanılan malzeme listesi): T1 -Transistor 2sc3358C1 – 10µF/35vC2,C9 – 1nFC3 ,C4 – 10nFC5,c6,c7,c8 – 10pFR1 – 470 OhmsR2 – 2.2 KR3 – 1KohmsP1 – 5KohmsL1,L2 – 2 turns 22AWG , 3mm Ø.L3,L4 – 10uH or 10 turns, 0.2mm Ø on ferrite..12 volts special power supply. 2sc3358 Transistörü kullanılarak Geniş Bant DTV UHF Anten TV Amplifikatör Devresi

project of circuit potency lineal RF amplifier with BLY90 for Fm transmitter or vhf transmitter Circuit for lineal amplifier for VHF with power source and printed circuit board, using the transistor Bly90 It is to be used as amplifier of potency of RF in the high strip of of the power source that should be capable to supply a tension of 13 volts with a current of 10 amperes. it demands right care in the assembly of the source. Terrified armored transformer, and three shocks of RF to filter the components of high frequency. XRF1 and XRF2 are 30 you turns of wire 25 AWG in a nucleus of ferrite of 1 cm of diameter and 5 cm length. It can use one of a source at/atx bad, it is easier. XRF3 are 100 you turns of wire 25 AWG in a ferrite nucleus and 1cm of diameter for 5cm of length. Or use an usually found in the exits of sources ATX’s. something around 100µH. The capacitors C1, C2, C3, C4 should be ceramic of 600 V or more and the capacitors of 10nF are for 100v. RX cannot be of wire. Power supply circuit for the rf lineal amplifier Orijinal görüntüsünü görmek için buraya tıklayın. 512x223 px. About the transistor BLY90 The Transistor BLY90 was developed to work in the classes THE, B and C, with 12.5V current of 8A. For applications above 175MHZ. Below we have the diagram circuit of the amplifier using an only transistor BLY90. All capacitors should be ceramic. The resistor of 10Ω for 1 w should not be of wire, the entrance impedance and exit is of 50Ω , soon it should be linked with cable of 50Ω . It should be observed the legal restrictions as the operation of that equipment type. Diagram circuit of the project for the rf lineal amplifier Orijinal görüntüsünü görmek için buraya tıklayın. 522x297 px. Printed circuit board for the lineal amplifier with bly90 Below we have the drawing of the printed circuit board of the transmitter, observe that the components are mounted beside the copper and with the terminals the shortest possible, use heatsink in BLY90. lists of material for assembly of the lineal RF potency amplifier Power Supply RX = 22KΩ 1W C1,C2,C3,C4 = 100nF 600V Ceramic C5,C6,C7,C8, =10NF 100V C9 = 100NF C10 = 4700µF C11 = 2200µF D1,D2,D3,D4 = 1N5401 or equivalent. XRF1,XRF2 = 30 turns of wire 25 AWG in nucleus of ferrite of 1cm diameter for 5 length. Optional, use a shock of RF of a computer source, those of the entrance of the net. XRF3 = 100 turns of wire 25 AWG in a nucleus of ferrite of 1 x 5. T1 = Transformer of 12 Volts for 10 Ámperes with screening. Several = box, plugs, cables, etc. Amplifier of RF Q = BLY90 R = 10Ω 2W C1 =15PF C2,C3,C4,C5 = 100PF C6 = 470NF C7,C10,C11 = 470PF C8 = 47PF C9 = 56PF C12 = 22PF CV1,CV2 = TRIMMER 4 – 40PF CV3,CV4 = TRIMMER 60PF MAX. L1 = 3 turns of wire 24 AWG with diameter of 7mm, nucleus of air. L2 = Shock of RF of 0.22µH. L3 = 15 turns of wire 24 AWG around a resistor of 47Ω x 2W (it doesn’t serve as wire) L4 = 3 turns of wire 24 AWG with diameter of 7 mm, nucleus of air. L5 = 1 turns (sees fig. below for details) L6 = 3 turns of wire 24 AWG with diameter of 7 mm., nucleus of air. L7 = 4 turns of wire 24 AWG with diameter of 7mm, nucleus of air. Several = printed circuit board, antenna, cables, heatsink, box, etc. Detail of L5. That project is just for ends of didactic test, that doesn’t implicate in any responsibility of the idealizator about the non operation or illegality of operation of the equipment.