Hi,
I am attempting to create a resistance controlled oscillator to use as a low power transmitter at 300 kHz. I am attempting to use a wien-bridge oscillator with a diode limiter. I am using a LM318N high speed op amp.
I have designed the circuit to oscillate at 300kHz using:
2*pi*f = 1/RC
I am using a high precision, low tolerance 2 pF capacitor with a 270k 5% tolerance 1/4 W power rating. I am using a Pioneer 1N914A diode.
When I simulate in PSpice using an LF411 I am able to achieve oscillations above 200kHz. Usually ~ 225kHz, I can't get higher but I am assuming that this is a limit of the model of the LF411. THe LM318N has a high slew rate and a gain bandwidth of 15 MHz.
When I created this circuit and actually went to test it I was oscillating at > 3MHz and was unable to get above 200 mVpeak.
I was wondering if there were common known problems about this circuit that might be causing this or if I need to excite the circuit in some way. Is there a way to upload my PSpice schematic so that you could view my circuit?
Any help would be greatly appreciated. Thanks in advance.
Greg McWilliams
I am attempting to create a resistance controlled oscillator to use as a low power transmitter at 300 kHz. I am attempting to use a wien-bridge oscillator with a diode limiter. I am using a LM318N high speed op amp.
I have designed the circuit to oscillate at 300kHz using:
2*pi*f = 1/RC
I am using a high precision, low tolerance 2 pF capacitor with a 270k 5% tolerance 1/4 W power rating. I am using a Pioneer 1N914A diode.
When I simulate in PSpice using an LF411 I am able to achieve oscillations above 200kHz. Usually ~ 225kHz, I can't get higher but I am assuming that this is a limit of the model of the LF411. THe LM318N has a high slew rate and a gain bandwidth of 15 MHz.
When I created this circuit and actually went to test it I was oscillating at > 3MHz and was unable to get above 200 mVpeak.
I was wondering if there were common known problems about this circuit that might be causing this or if I need to excite the circuit in some way. Is there a way to upload my PSpice schematic so that you could view my circuit?
Any help would be greatly appreciated. Thanks in advance.
Greg McWilliams