current source

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  1. victoriomariani

    Emitter and receiver optical signal with transimpedance

    Hello fellow electronics enthusiasts, I'm seeking some advice regarding an issue I've encountered with an electromagnetic wave emitter. Despite covering the photodiodes, I'm still detecting a signal at the same excitation frequency as the LEDs. The emitter and receiver circuit are show here...
  2. T

    How and when to use a NMOS and PMOS as current source/sink and voltage source in a circuit?

    as my question state, I am having trouble understanding the circuit using a NMOS/PMOS as a current source or voltage source according to the pins they are connected and also the input and output impedance present when looking at only one pin of the MOS. my lack of understanding comes in the...
  3. D

    Current source for pulse oximeter purpose

    Hi, I'm designing LED driver in my pulse oximeter. It would be two LED's, I would like to auto adjust current by DAC and be able to turn off one LED at time. I came up with an idea. In simulation, I got what I wanted. What about real circuit? The mosfet is actaully IRLML6244TR. 5V is for. ex...
  4. M

    Quad 100k Digital Rheostat - Can it be wired for 300k?

    Hi, I have a Fairchild FL51x0 which has a control pin where the voltage at the pin is input to an 8 bit ADC with 2.5V reference. The pin sources 10uA current, so that an external resistor can be used to set the voltage (0-250k). I'd like to use a Digital Potentiometer/Rheostat. However, the...
  5. J

    Understanding noise RMS and picking an appropriate current source for Hall probes

    Hi Everyone, I am trying to define the most suitable current source for my application. Essentially, I need a high stability current source to feed Hall probes sensors. The probes' nominal current is 10 mA. A stability of 100 ppm (i.e., 1 uA) for short term (a few hours) is desired. Usually, I...
  6. M

    Using an Opto to Control a Current Source to Create a Voltage Input

    Hi, I am using an FL5150 IC, that has a control pin ('dim') with a 10uA current source on it. Their datasheet shows a variable resistor 0-250k which creates a voltage of 0-2.5V. I want to drive/control this using an isolated PWM signal. I've simulated many circuits using the Vdd pin...
  7. C

    Driving solid state relay input

    Can a 4-20 mA (constant VDC) analog output on an industrial controller be used as an input on a solid state relay? I wasn’t sure how a device behaving as a variable current source might interact with a load such as the LED in an solid state relay that varies in its current draw. For example...
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