Published:2009/6/23 2:09:00 Author:May
This oscillator uses mauctivity coupled emitter and collector windings to its main tank circuit.Take care so that L1 and L2 are not coupled to each other, otherwise this circuit is susceptible to parasitic at other frequencies.Typically ,L1 has 5 to 10 times the number of turns that L2 has.L1,L2,L3 are woundon same coil form. This oscillator is more suited to lower frequencies,≤10 MHz. (View)
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Published:2009/6/23 2:09:00 Author:May
In this circuit, an additional exclusive-OR gate is connected after the modulo-2 feedback, with C1 and R2 applying the supply turn-on ramp into the feedback loop. This provides sufficient transient signal so that the PRBS generator can self-start a power-up. A shift-register length n of 10 is shown with feedback at stages 3 and 10, providing true and inverted maximal length sequence outputs.
This technique applies an input directly to the feedback loop. Therefore, it's considered more reliable than applying an RC configuratior) to the shift-register reset input to create a random turnon state. (View)
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Published:2009/6/23 2:08:00 Author:May
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Published:2009/6/23 2:05:00 Author:May
This circuit will generate an AM-modulated signal in the AM broadcast band that can be picked up on a receiver.About 2V of audio input will produce about 30% modulation of the oscillator signal.An old AM broadcast oscillator coil or other two-winding coil with about a 10:1 turn ratio and about 50 to 150 μH inductance can be used for T1. (View)
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Published:2009/6/23 2:03:00 Author:May
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Published:2009/6/23 2:22:00 Author:Jessie
This typical HF VFO circuit has several stability-enhancing features, including well-chosen capacitor types. The frequency of the VFO is approximately 2π (C1 + C2 + C3) L1. L1 should be an aircore type coil, rigidly mounted, with high (>200 value) value of Q. (View)
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Published:2009/6/23 2:03:00 Author:May
The 1-dB pad is useful as a termination in RF work to limit possible mismatch range between system blocks, etc. (View)
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Published:2009/6/23 2:02:00 Author:May
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Published:2009/6/23 2:22:00 Author:Jessie
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Published:2009/6/23 2:01:00 Author:May
This simple JFET-based variable-frequency oscillator can be used in receiver and transmitter circuits. (View)
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Published:2009/6/23 2:20:00 Author:Jessie
This noninverting circuit uses a pair of com-plementary npn (2N3904) and pnp (2N3906) transistors. (View)
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Published:2009/6/23 2:20:00 Author:Jessie
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Published:2009/6/23 2:00:00 Author:May
This octal digital-to-analog converter operates on 5V and provides eight output voltages, each digitally adjustable from supply rail to supply rail (0 to 5V). Each output's resolution is 20 mV/LSB. The DAC chip (IC1) requires 3.5V of headroom between its VDD and reference voltages. However, a voltage-doubler charge pump (IC2) removes this limitation by generating an approximate 10-V supply for VDD. All of the converter references are connected to the 5-V supply. IC2 doubles the 5-V input to an unregulated 10-V output that has an output impedance of less than 10Ω. It can deliver 100 rnA, which enables the eight DACs to issue their maximum output currents simultaneously (8×5 mA = 40 mA). (View)
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Published:2009/6/23 2:00:00 Author:May
This circuit can be used for FM wireless audio, microphone, and part-15 applications where a stable frequency modulated oscillator is needed. LT can be varied to cover 75 to 150 MHz, as needed. (View)
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Published:2009/6/23 1:59:00 Author:May
Unusual frequency compensation gives this logarithmic converter a 100 μs time constant from 1 mA down to 100 μA, increasing from 200 μs to 200 ms from 10 nA to 10 pA. Optional bias current compensation can give 10 pA resolution from - 55 ℃ to 100 ℃, Scale factor is 1 V/decade and temperature compensated. (View)
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Published:2009/6/23 1:58:00 Author:May
Here: L1≈7μH/f, C1≈C2≈C3≈2400pF/f, where.f is in MHz. In this circuit, the oscillator is free-running. (View)
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Published:2009/6/23 1:58:00 Author:May
The DDS chip (U1) generates a data stream that is converted by D/A converter U2 into a sine wave. U1 is programmed via the input from P1, from the LPT port of an IBM PC. The system uses a 40-MHz TTL output clock module. (View)
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Published:2009/6/23 1:58:00 Author:May
These circuits are for use with a crystal-controlled LO usmg the NE602 C1,C2,and C3 arefor crystals in the 5-MHz region and are approx⒈mately chosen from
C3 is for fine tuning the crystal frequency and will be 20 to 50 pF typically. (View)
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Published:2009/6/23 1:58:00 Author:May
The brightness of a lamp or lamps can be varied with this circuit. The snubber circuit values are typically 0.1 μF and 100-Ω.R8, is typically 25 to 100 kQ. (View)
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Published:2009/6/23 1:57:00 Author:May
Power booster is capable of driving mod-erate loads. The circuit as shown uses a NE5535 device. Other amplifiers may be sub-stituted only if R1 values are changed because of the ICC current required by the amplifier. R1 should be calculated from the following ex-pression: (View)
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