Using JFET as magnetic field sensor

In summary, the conversation revolves around the possibility of using a pulsed magnetic field to switch a JFET on and off. The mention of ECG94 leads to a discussion on using Hall sensors to trigger coils and the potential of using JFETs for magnetic switching. However, there are concerns about how this would work and the need for an amplifier to measure the voltage difference. Ultimately, the question remains if it is possible to use a magnetic field as a trigger for turning on and off a JFET.
  • #1
Jdo300
554
5
Hi,

I am wondering if it is possible to switch a JFET on and off with a pulsed magnetic field. A friend of mine was playing around with a circuit where we was using some Hall sensors to trigger coils on and off. When I asked him for the part numbers for the hall sensors, he told me ECG94. When I looked that up, all I found was something about a voltage regulator and a JFET. Maybe he just misread the package but could it be possible that he is able to magnetically switch his coils on and off using JFETS?

Thanks,
Jason O
 
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  • #2
i think the Hall effect is useful for differentiating between negative charge carriers with positive mass (electrons) and positive charge carriers with effectively postive mass (holes). unless the two pads for the gate are separately connected to their own terminals on the FET, i am not sure how you would be able to measure a change of magnetic field (that would result in a potential difference between the "top" pad and the "bottom" pad).
 
  • #3
Actually, if I could, I would be happy with using the magnetic field simply to switch the FET on and off... like a trigger. Is that possible?
 
  • #4
Jdo300 said:
Actually, if I could, I would be happy with using the magnetic field simply to switch the FET on and off... like a trigger. Is that possible?

i'm not sure how a constant magnetic field could do it without making some kind of amplifier for the measured voltage difference (Hall effect) since, if a coil were just hooked up between the gate and drain, you would need a voltage from a changing magnetic field to turn off an FET.
 

1. What is a JFET and how does it work as a magnetic field sensor?

A JFET (Junction Field-Effect Transistor) is a type of transistor that uses a voltage-controlled channel to regulate the flow of current. In a JFET-based magnetic field sensor, the magnetic field induces a voltage in the channel, causing a change in the current flow. This change in current can then be measured and used to detect the presence and strength of a magnetic field.

2. What are the advantages of using a JFET as a magnetic field sensor?

One advantage of using a JFET as a magnetic field sensor is its high sensitivity. JFETs are highly responsive to changes in current, making them ideal for detecting small variations in magnetic fields. Additionally, JFETs have a wide dynamic range, meaning they can detect a broad range of magnetic field strengths.

3. How accurate is a JFET-based magnetic field sensor?

The accuracy of a JFET-based magnetic field sensor depends on various factors, such as the quality of the JFET used, the circuit design, and the calibration process. However, with proper calibration and design, JFET-based sensors can achieve high levels of accuracy, making them suitable for many applications.

4. Can a JFET-based magnetic field sensor be used in harsh environments?

Yes, JFET-based magnetic field sensors can be used in harsh environments. This is because JFETs are typically more robust than other types of transistors and can withstand a wide range of temperatures and environmental conditions. However, it is essential to choose a JFET with suitable specifications for the specific application.

5. What are some common applications of JFET-based magnetic field sensors?

JFET-based magnetic field sensors have various applications, including compasses, position sensors, magnetic encoders, and current sensors. They are also commonly used in scientific research, such as in the study of magnetism and the Earth's magnetic field. Additionally, JFET-based sensors are used in industrial and commercial settings, such as in automotive and aerospace industries, for their high sensitivity and accuracy in measuring magnetic fields.

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