Variable Frequency Oscillator
Variable Frequency Oscillator - Related Videos
10:22
Interictal High Frequency Oscillations Detected with Simultaneous Magnetoencephalography and Electroencephalography as Biomarker of Pediatric Epilepsy
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Cited by 59 •
2016
High Frequency Oscillations (HFOs) have emerged as presurgical biomarkers for the identification of the epileptogenic zone in pediatric patients with medically refractory epilepsy. A methodology for the noninvasive recording, detection, and localization of HFOs with simultaneous scalp electroencephalography (EEG) and magnetoencephalography (MEG) is presented.
02:39
In Vitro Recording of Theta Oscillations in the Mouse Hippocampus
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2025
This video demonstrates the recording of rhythmic neuronal network activity, also known as theta oscillations, in an isolated hippocampus. Electrodes are inserted into various layers and spatial positions to detect and analyze theta oscillations. This shows the unique neuronal compositions and the connectivity of the neuronal network across different layers of the hippocampus.
06:34
Infant Auditory Processing and Event-related Brain Oscillations
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Cited by 30 •
2015
High-density electroencephalography (dEEG) is being used increasingly to study brain development and plasticity in the early years of life. Here we present an application of sophisticated analysis techniques that builds on traditional EEG recording to understand the oscillatory dynamics of rapid auditory processing in the infant brain.
01:32
Evoked Gamma Oscillations for the Treatment of Alzheimer’s Disease
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2025
Begin with a patient diagnosed with Alzheimer’s disease, wearing a gamma therapy stimulation device.The device consists of an eye-set and headphones.Using the controller, activate the device to deliver auditory and visual stimulation.The visual component emits flickering light at a gamma frequency, while the auditory component produces synchronized sound pulses.Gamma oscillations are brain waves generated by synchronized neuronal firing, crucial for cognition and memory.In AD, these...
09:10
Fabrication and Testing of Microfluidic Optomechanical Oscillators
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Cited by 10 •
2014
Parametric optomechanical excitations have recently been experimentally demonstrated in microfluidic optomechanical resonators by means of optical radiation pressure and stimulated Brillouin scattering. This paper describes the fabrication of these microfluidic resonators along with methodologies for generating and verifying optomechanical oscillations.
FAQs
Positive feedback returns part of the circuit’s signal so the recurring waveform can continue, while the frequency-selective network favors the timing of that waveform. The feedback mechanism and selective network therefore perform different jobs: feedback sustains the signal, whereas the LC or RC network determines its oscillation rate. This interaction enables controlled frequency adjustment.
The network type determines which circuit properties control the oscillation rate. An LC arrangement provides frequency selection through inductance and capacitance, while an RC arrangement uses resistance and capacitance in its frequency-selective behavior. Adjusting an available capacitance, inductance, or control voltage changes the selected rate, so the network choice affects how tuning is implemented.
Frequency stability depends on the consistency of the components that establish the selective network. Temperature changes or component variations can alter the effective circuit conditions, shifting the oscillation rate away from its intended value. Engineers must therefore consider stability alongside tuning range when applying a VFO to communication, measurement, timing, or control systems.
A control voltage provides an electrical way to alter the oscillation rate rather than relying only on a manually changed circuit element. When the voltage changes the frequency-selective conditions, the oscillator moves to a different frequency. This approach supports tunable signal generation and frequency control, including systems that need adjustable communication channels or synthesized frequencies.
A basic setup begins by selecting a frequency-selective network, such as an LC or RC circuit, and incorporating a means to vary capacitance, inductance, or control voltage. The design then establishes positive feedback so oscillation can continue. Finally, engineers evaluate the desired tuning range and frequency stability, including sensitivity to temperature and component variation.
Engineers use VFOs when a system needs an adjustable periodic electrical signal. Applications include signal generation, radio tuning, frequency synthesis, measurement, and control systems. The resulting output can provide a tunable timing or communication reference, while its measured frequency and stability reveal how effectively the feedback and frequency-selective network perform under changing component or temperature conditions.