Published:2011/11/29 1:46:00 Author:Ecco | Keyword: Konka , repairing diagram
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Published:2011/11/29 1:45:00 Author:Ecco | Keyword: Motorola, repairing
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Published:2011/11/28 21:45:00 Author:Ecco | Keyword: IC, AM radio
The receiver ( Figure a) input circuit is supplied by the 60Ω generator. Low -pass filter allows the entire frequency range with uniform sensitivity . Figure b shows the receiver input circuit coupled with transmitter inductive (Ri = 60Ω). Figure c shows the input circuit with ferrite ferrite antenna, the antenna structure is shown in Figure (d).
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Published:2011/11/28 21:37:00 Author:Ecco | Keyword: usb , switching to 232
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Published:2011/11/11 2:17:00 Author:Ecco | Keyword: 6w , FM power amplifier
Assemble by soldering the components to the pads indicated. Keep coil, resistor, and capacitor leads as short as possible. The coils should be 3/16 to 1/4 above the board and separate turns by one wire diameter. Bend leads to form a little mounting foot for soldering to the circuit board. Tuning and power output are affected by the distance between the coil turns, you can make fine adjustments by either spreading or compressing the coil slightly. The area surrounding the pads is ground. C2, C3, C4, C6, C7, C8, C9, C10, L2, and R1 are soldered at one end to ground as well as the shield braid on the coax cables. Bolt Q1 to a small heat sink or the chassis with heat sink thermal compound or gray thermal pad underneath the tab. With an input level of 200-500mw, you should see an output of 5-6 watts. Be sure to have a proper dummy load (50 ohms) or tuned antenna connected to the output, doing otherwise will likely destroy the transistor.
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Published:2011/11/28 21:37:00 Author:Ecco | Keyword: FM transmitter
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Published:2011/11/28 0:57:00 Author:Ecco | Keyword: 45MHz , FET oscillator
The circuit's quartz crystal is between the source and drain of field effect transistor. The operating point is determined by the source resistor. Inductor and capacitor form a series resonant circuit.
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Published:2011/11/28 0:53:00 Author:Ecco | Keyword: crystal oscillator , 2MHz
Figure (a) and (b) show the two 2MHZ basic oscillator circuits. According to the circuit structure, it can adjust its best operating point by testing.
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Published:2011/11/28 0:31:00 Author:Ecco | Keyword: Logarithmic, sweep , voltage controlled oscillator
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Published:2011/11/24 20:49:00 Author:Ecco | Keyword: sine wave oscillator
The chart shows the sinusoidal oscillator circuit using LM386; the circuit uses the Wien bridge oscillator method, and the distortion factor of output signal of is very low. Small bulb H and resistor R3 form the negative feedback circuit, which makes sure that the signal amplitude output by oscillator is stable and has low distortion. When the capacitors C1, C2 values are the same , and they use the icon data, the sinusoidal frequency is 1KHz. When it is in actual production , H can select 3V, 15mA small bulb.
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Published:2011/11/24 20:53:00 Author:Ecco | Keyword: Triangle wave , square wave , generator
The circuit is composed of 3 operational amplifiers, and changing resistor R can change the frequency.
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Published:2011/11/27 20:28:00 Author:Ecco | Keyword: Parallel resonant , crystal oscillator , Gate circuit
When the quartz crystal under the action of the applied voltage, it will produce a piezoelectric effect, then the quartz crystal produces the mechanical vibrations, when the frequency of the applied voltage and crystal's natural oscillation is the same, the crystal 's mechanical amplitude is the largest and the alternating electric field will be largest to form piezoelectric resonator. The reactance frequency characteristics of quartz crystal reactance show that it has two closed resonance volume ratio, one is the series resonant frequency , the other one is parallel resonant frequency , when the crystal is in series resonance, the reactance is minimum, when it is in parallel resonance, the reactance is maximum, when it is between two frequency ranges, the crystal shows inductive , when it is free from two frequency ranges, the crystal shows capacitive.
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Published:2011/11/27 21:05:00 Author:Ecco | Keyword: pulse generator , sharp pulse , sawtooth pulse
The upper limit of the two pulses' frequency generated by the gate circuit is 5MHZ, the lower limit depends on the size of the capacitor . Sharp pulse width is about 50ns, which is output directly from TTL and non gate; sawtooth pulse is generated by impedance converter, which is a Schmitt trigger with high input impedance, so that it has a good sawtooth linearity . Gate device substitution : FLH731-49713S, FLH491-49702.
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Published:2011/11/27 20:49:00 Author:Ecco | Keyword: pulse generator , multiple waveforms
It uses the programmable unijunction transistor Th to form a pulse waveform generator circuit which can output multiple waveforms. Figure (b) shows the pulse waveforms output by a, b, c, d points which are shown in Figure (a) circuit. In this case, UB = 50V, pulse frequency f = 1000Hz, pulse peak U = UP = 20V. Component parameters R1 = 0.164MΩ, R2 = 0.256MΩ, R3 = 4.9MΩ, R4 or R5 = 8Ω, C = 410pF.
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Published:2011/11/24 21:30:00 Author:Ecco | Keyword: crystal oscillator , switch
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Published:2011/11/24 21:30:00 Author:Ecco | Keyword: Adjustable crystal oscillator
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Published:2011/11/27 20:42:00 Author:Ecco | Keyword: Crystal , l00kHz , interval calibration , oscillator
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Published:2011/11/27 20:41:00 Author:Ecco | Keyword: Transistor, FET transistor , oscillator
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Published:2011/11/28 21:01:00 Author:Ecco | Keyword: audio signal generator, low output resistance
As it is output from the emitter follower, the output resistance is very low. Output voltage can be decided by R1, R2 piezoelectric resistance. If you want to get sinusoidal signal without distortion, you can access resistor R3, its value is determined by the test adjustment. In the case of parameters, the frequency of the circuit is about 500Hz.
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Published:2011/12/7 20:33:00 Author:Ecco | Keyword: power circuit , CASPER , VGA , color display
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