RF FM Oscillator

684

10:39:12

An RF oscillator which can become an FM modulator very easy. Gives a very clean sinewave.By ungrounding the base capacitor and hooking it up with a signal source. It provides over 18Vpk-pk / 9Vmax / 7V RMS at impedance as low as 1.3Kohm but works best with 10Kohm. If you wanna turn it into a transmitter you must add an external current amplifier because if you hook the antenna directly into the oscillator the impedance will be unmatched and the oscillations will fade into nothing

published 11 years ago

wyoelk

11 years ago

What does the diode do? Is there feedback from somewhere in the circuit? I haven't seen many dc circuits with diodes, in my extremely limited world. So teach me @thebugger

thebugger

11 years ago

The diode is to prevent feedback from the inductor into the power supply. Check the current consumption with the diode and without it and you'll see what I mean. With the diode there the capacitor takes on the feedback while the power source is back to normal.

wyoelk

11 years ago

Thank you. Isee the differences without the diode or resistor

thebugger

11 years ago

Usually the diode or the resistor is not needed except when you're using batteries. A power supply has filters at both the input and output that can sink the reverse current but when using a battery the only thing that's holding the surge is the diode with a capacitor. The resistance represents the internal resistance of the battery.

zorgrian

11 years ago

I do NOT see any diode! Has this circuit been modified since the previous comments were made?

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