Amplified Hartley Oscillator

beenthere

Joined Apr 20, 2004
15,819
Are you sure that your oscillator output is only 4 nanovolts? How did you even find it? Some of the output has to feed back in order for oscillations to continue - that level is certainly not enough.
 

Thread Starter

yy.toh@live.com.my

Joined Mar 9, 2011
5
Are you sure that your oscillator output is only 4 nanovolts? How did you even find it? Some of the output has to feed back in order for oscillations to continue - that level is certainly not enough.
Now I wonder where is the location of the output.

at base before the coupling capacitor:
V peak to peak 500mV
I peak to peak 100mA

at base after the coupling capacitor:
V peak to peak 40uV
I peak to peak 8uA

at collector:
V peak to peak 300nV
I peak to peak 300nA

The values at collector is smaller than the base, i donno why
 

beenthere

Joined Apr 20, 2004
15,819
I think you are misreading the results of the simulation. You are asking a lot with those 1 ohm resistors. Generally, you make the oscillator and then amplify the signal. Perhaps Multisim will let you use unusual component and values.
 

Thread Starter

yy.toh@live.com.my

Joined Mar 9, 2011
5
I think you are misreading the results of the simulation. You are asking a lot with those 1 ohm resistors. Generally, you make the oscillator and then amplify the signal. Perhaps Multisim will let you use unusual component and values.
I think there is no missreading, the readings are directly from the simulation probe.
The peak to peak values are still in uV even I increased the resistor values.
 

Wendy

Joined Mar 24, 2008
23,457


There is no real feedback there, I don't think it can work. You have one of the coils shorting the power supply, instant smoke. L1 should be going to the collector of the transistor and ground. You will need to dramatically increase the values of the resistors, 2 amps just for base bias (6V/2Ω)?

Colpitts...



Hartley...



They are more similar that you might first think. The concept is an inverting amplifier with a tank circuit that also inverts the signal. Work on the transistor amplifier a bit more first.

.
 

Attachments

Last edited:

Wendy

Joined Mar 24, 2008
23,457
Here is a design I cobbled together. It has never been tested, but I suspect it will work first time. I am allowing the coils to conduct DC through to the transistor, turning what is a problem with your design into an asset with mine.



C2 is a power supply filter cap, and C3 will increase the gain of the transistor circuit. It might be eliminated with improved results.
 

Attachments

Top