Hello. I was wondering if a JFET can be used as a constant current source and if so how do you use it as one.
Depends upon the current required and the precision/accuracy needed for the current.Hello. I was wondering if a JFET can be used as a constant current source and if so how do you use it as one.
You take a antenna, lead it to a tank circuit, lead that to a transformer, the diodes to rectify it to DC then to capsitors and a resistor to build up charge then to a non transistor to turn off once the voltage from the capsitor drops to low due to discharging. Then to zenner diodes that are reverse bias to have constant voltage then to something the makes a constant current then to a loadDepends upon the current required and the precision/accuracy needed for the current.
More accurate constant current circuits can be made using a couple transistors, or a transistor and an op amp.
What's the purpose of the constant current?
All that to capture a few microwatts of power?You take a antenna, lead it to a tank circuit, lead that to a transformer, the diodes to rectify it to DC then to capsitors and a resistor to build up charge then to a non transistor to turn off once the voltage from the capsitor drops to low due to discharging. Then to zenner diodes that are reverse bias to have constant voltage then to something the makes a constant current then to a load
The idea is to capture a radio wave at a certain frequency using the antenna and tank circuit then use a transformer to turn the millivolts from the radio wave into volts, and then rectify the current and voltage to DC using diodes then feed that current into supercapsitors in series, so you can handle higher voltage than just one supercapsitor and have a high enough farad, so when the capsitors discharge though a resistor in series with the capsitors, you can still get a higher voltage with at least a amp or two current then from there use a reverse bias zenner diode to keep the voltage the same, because when the capsitor discharges, it decreases little by little in voltage same as it does with current, so after the zenner diode have something like a FET or a l200c regulator keep the current constant before it goes to the load.Maybe if you provide a clear and simple idea of what you want to do somebody can suggest a circuit for doing that.
Let me take a guess: Do you want to flash an LED with energy picked up by an antenna and tuned circuit?