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Last Updated on: Thursday, March 22, 2012 07:53 AM

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Radio Frequency (RF) Oscillators

  • 175kHz Inductive Pulse Receiver
    This circuit is discussed in more detain in the Experimenters Journal. The receiver’s six inch diameter coil detects the ring signal from the above transmitter and use a single NPN transistor to provided enough amplification for the signal to be easily viewed on an oscilloscope.
  • CMOS Iinverter Parallel LC Oscillator
    I have used this parallel resonant LC oscillator circuit countless times.  The oscillator frequency is determined by the inductor and capacitor values.  I have shown an adjustable inductor to make it easy to set the frequency to a specific value.  Once set the frequency is fairly stable over supply voltage variations and temperature changes.  The values shown are for 125KHz but the frequency can range from tens of kilohertz to tens of megahertz.   With a 74HCU04 type inverter, it will oscillate down to about 1.5 volts.  If the frequency is low, you can also use a 74C04 (CD4069) inverter.
  • CMOS Inverter 125kHz LC Oscillator
    This circuit uses a single CMOS inverter to form a series resonant LD oscillator.   The values shown set the oscillation at about 125KHz buth other frequencies are possible by changing the main LC values.
  • CMOS Inverter Parallel LC Oscillator
    I have used this parallel resonant LC oscillator circuit countless times.  The oscillator frequency is determined by the inductor and capacitor values.  I have shown an adjustable inductor to make it easy to set the frequency to a specific value.  Once set the frequency is fairly stable over supply voltage variations and temperature changes.  The values shown are for 125KHz but the frequency can range from tens of kilohertz to tens of megahertz.   With a 74HCU04 type inverter, it will oscillate down to about 1.5 volts.  If the frequency is low, you can also use a 74C04 (CD4069) inverter.
  • CMOS Inverters Form 125kHz Oscillator
    This circuit is similar to schematic CMOS INVERTER 125KHz LC OSCILLATOR but inverts the LC components so the inductor is grounded.  Two inverters are needed to produce the needed oscillation.  Again, the values shown set the frequency at 125KHz but can be changed to produce other frequencies.
  • CMOS Nand Gate Forms Gated 125kHz Oscillator
    This circuit is similar to schematic number 116 but uses a NAND gate as an inverter.  The gate allows the oscillator to be gated on and off.  Again, the values shown set the frequency at 125KHz but can be changed to produce other frequencies.
  • Medium Power 125kHz Oscillator
    This circuit is similar to CMOS INVERTERS FORM 125KHZ OSCILLATOR but adds more inverters in parallel to deliver yet more power.  The values shown are for 125KHz.
  • Medium Power 125kHz Oscillator-2
    This circuit is similar to MEDIUM POWER 125KHZ OSCILLATOR but adds even more inverters in parallel to deliver yet more power.  The values shown are for 125KHz.
  • Ultra Pure 125kHz Sine Wave Signal Source
    For some RFID systems operating at 125KHz, a very low distortion signal source reference is needed.  The circuit shown on this page produces a 10-volt peak-to-peak signal into a 50-ohm load, with a distortion of only 0.01%.

More  Radio Frequency (RF) Oscillators

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Dave's Circuits:  Astable Oscillator Circuits        Audio Oscillator Circuits        Crystal Oscillators      Sine Wave Oscillators
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