Oscillator Schematic 3 to 7 MHz and 217 Mhz

[gedfire]

Hello All,

I would like a schematic that would help me to create a simple oscillator that can drive an aircore coil or other components at 3 to 7 MHz and 219 MHz approximately.Any help is appreciated.



Gary

 

[NascentOxygen]

One of the problems with "simple" oscillators is that they can't deliver much power to any circuit, and that they change their frequency or stop oscillating when you connect a load. So you usually need a buffer between the oscillating stage and the load. So we are moving away from "simple".

The simplest arrangement may be where it is feasible to use the aircore coil as the inductance in the resonant circuit of the oscillator itself. You'd need to switch or vary capacitors to change the frequency.

A google search on "RF oscillator" should turn up a surfeit of candidates. For a 200MHz oscillator you may need a different circuit, one less forgiving to construction liberties.

 

[Enthalpy]

At 3 to 7 MHz you can have a Schmitt trigger oscillate. Easy, reliable.

At 200MHz you need experience. If not, you will fail. Your best hope would be a completely freezed design, already at your precise frequency, where the printed circuit is fully drawn - something like a kit.

 

[NascentOxygen]

I would like a schematic that would help me to create a simple oscillator that can drive an aircore coil or other components at 3 to 7 MHz and 219 MHz approximately.Any help is appreciated.

A couple of transistor oscillators w/ handy construction hints & cautions, for the 4 MHz range:
http://www.sm0vpo.com/blocks/osc7m00.htm
http://ece.wpi.edu/courses/ece2011/labs/lab5A09final.pdf

Many are listed here: http://www.epanorama.net/links/oscillator.html
including a simple CMOS hex inverter oscillator: http://www.ee.washington.edu/circuit_archive/circuits/F_ASCII_Schem.html#ASCIISCHEM_004

Guaranteed hours of fun!

 

[NascentOxygen]

A one transistor oscillator in a metal detector. http://www.next.gr/oscillators/rf/RF-oscillator-circuit-2N3904-l6324.html

 

[gedfire]

One of the problems with "simple" oscillators is that they can't deliver much power to any circuit, and that they change their frequency or stop oscillating when you connect a load. So you usually need a buffer between the oscillating stage and the load. So we are moving away from "simple".

The simplest arrangement may be where it is feasible to use the aircore coil as the inductance in the resonant circuit of the oscillator itself. You'd need to switch or vary capacitors to change the frequency.

A google search on "RF oscillator" should turn up a surfeit of candidates. For a 200MHz oscillator you may need a different circuit, one less forgiving to construction liberties.

Thanks for your informed response.I appreciate it.


Ged

 

[gedfire]

At 3 to 7 MHz you can have a Schmitt trigger oscillate. Easy, reliable.

At 200MHz you need experience. If not, you will fail. Your best hope would be a completely freezed design, already at your precise frequency, where the printed circuit is fully drawn - something like a kit.

Thanks for replying, where could I get such a kit?

Regards,
Gary

 

[NascentOxygen]

Within what frequency range could the 217 (or is it 219) MHz oscillator be? What application do you have it mind for this?

 

[NascentOxygen]

It might be feasible to use a VCO module, like one of these: http://www.digchip.com/datasheets/parts/datasheet/302/POS-150-pdf.php

The output is sinusoidal with some harmonic. http://www.minicircuits.com/app/VCO15-20.pdf