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I would like to add an indicator light to a system. It has to be bright, so LED.

The signal source for that indicator cannot provide enough current for even a basic LED. I don't want to design a whole circuit to amplify a signal. Are there any components that are simply indicators with built-in amplifier so they take GND, 5V and on/off signal for example?

EDIT: I know that could be done with 3-4 additional elements (transistor, few resistors.) I just hoped that this is a frequent enough use case for an indicator that something like this would exist as an integrated component, and that I just cannot find it (not knowing how it is actually called.)

I am searching Farnell and google but it seems that I cannot figure out the proper keywords for such functionality.

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    \$\begingroup\$ An amplifier can be just a single MOSFET (with built in resistors) - is that too much?! \$\endgroup\$ Commented Jun 4, 2021 at 13:14
  • \$\begingroup\$ Can you add some details to the question describing the LED you want to use (especially forward voltage and current). If the LED is nothing special, there's no reason to avoid a simple driver transistor like @awjlogan said. \$\endgroup\$ Commented Jun 4, 2021 at 13:49
  • \$\begingroup\$ Your question is missing a lot of details. Signal source (opamp output, GPIO pin. pH sensor, EKG probe, etc.), peak voltage, frequency, current capability. Also, LED forward voltage Vf, typical current, datasheet or vendor page, etc. Depending on the answers, this might be doable with one small transistor and one resistor. \$\endgroup\$ Commented Jun 4, 2021 at 14:50
  • \$\begingroup\$ @awjlogan It is too much if it turns out I will need several such indicators, and we have multiple boxes to build. \$\endgroup\$ Commented Jun 4, 2021 at 17:21
  • \$\begingroup\$ @AnalogKid I hoped that I just missed something in my queries. The use case is the LED, switched on by Raspberry Pi GPIO, or even better, UART output (this is the neat trick to detect when Raspi shuts down). 3.3V signal, negligible input current on signal port and 5V on power port. \$\endgroup\$ Commented Jun 4, 2021 at 17:21

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It can be accomplished by something like this:

led mosfet ckt

(Image source: Raspberry Pi driving a LED through a MOSFET by moscardo)

This is an example circuit and you will have to modify it according to your requirements.

Lets start with LED - How bright do you need your LED to be? What is the voltage and current required? Answer these questions and find out a suitable part. There is a high chance that you can make it work with a 5V supply. If not, you might have to change the LED power source voltage accordingly.

Depending upon the LED current requirements, you will have to calculate the value of R3.

Depending upon the LED current value, you also need to find a suitable mosfet or transistor that can handle the current. Better to go with a part that can be activated by 3.3 V logic (or 5V if you MCU runs on 5V).

You can use a typical value of 10K as R2. R1 can be around 220 ohms to 1000 ohms. It should work just fine.

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  • \$\begingroup\$ Thank you for that, of course that could be done, but hoped to avoid any kind of soldering. This already requires a small board to put the elements on, and I was aware that this is possible. \$\endgroup\$ Commented Jun 4, 2021 at 17:16

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