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10 Threads found on Constant Current Source Fet
Hello I am making 1ma current source for constant - - - Updated - - - Sorry for mistake Continue......I am making 1ma constant current source for PT100 sensor using OP07 op-amp. I am using a voltage divider for negative pin and a series resistance for positive input pins. At the (...)
GBW product of most Op Amps are low, so use unity gain. ESR of LED is low ( 15 Ohms ) so emitter resistor should be low ( 100 ) Then to make constant current sink use feedback from emitter or fet source instead of OA output. e.g. I would design this way THen the BW is limited only by the Op Amp's max BW at low gain. (...)
This sounds like a stepper motor drive drive where the high side switches just provide a current limited PWM source. Stepper motors need lots of current, and a high voltage to get them to work quickly due to the time constant (L/R) of their coils, the old way was to put a high power resistor in series with them, so you (...)
I want to incorporate a 10mA constant current sink into a design as a sort of dummy load to bias a larger current driver. I found the Texas Instruments REF200 but it only sinks 100uA. Then I also found the NXP PSSI2021SAY but it is unclear to me whether I can use this part as a sink despite being intended as a source. Can (...)
Hello, The oscillator design attached uses a simple bc547 and a LED (red circles) as a contant current source for the buffer amplifier fet (am I right?) Could I use the constant current source circuit shown inside the square to replace the current (...)
Try: The fet constant-current source/Limiter :wink: IanP
Hi. I would recomend just using an opamp and a fet to make constant current source. The input voltage is what you get from the ad584 circuit.
The source current is determined by the Gate to source voltage. See the data sheet of whatever fet you are using. Yes, the Gate/source area does charge and that creates the electric field that causes the source current. But if the Gate voltage is (...)
I send you collection of articles-circuits for fet constant current. Have a good work.
hello i am using LTC1871 as a constant current led driver in boost mode (12 to 28v) at 10W. The current sense for the fet source pin is 150mV......but the reference for the current in the LED string is set at 1.23V. This would give high dissipation in the led (...)