Vu meter on LM3914

I recently made such a simple Vu meter on the LM3914 chip:
In the beginning, I did it on ordinary 3V 5mm diodes with 500Ω resistance, but they emitted too little light. Therefore, I replaced it with a 5 cm long LED strip (3 diodes). One meter of tape consumes 4.8W of power, that is, a 5cm piece of tape is 0.24W or 20mA. But when I hooked the tape, it became dark.
My question is, is it possible to amplify these LEDs in some way to make them emit stronger light? Or maybe LM3915 is the better option than LM3914?
Much appreciate.

Hi Stan,

This forum is more to do with schematic drawing and printed circuit board design and building, rather than electronic design, however:

LM3915 & LM3914 are basically the same except one is linear and the other logarithmic.
You may increase/decrease the brightness of your LEDs by altering the voltage supplied within the specifications of the ICs and LEDs. Refer to the data sheets for maximum and minimum voltages and currents both the ICs and LEDs can handle.

Maybe a forum on electronic design would better suit your question.

Cheers, J.

Be curious.
Read the datasheet. Use a multimeter to check voltages and currents, and compare those with your interpretation of the datasheet.
Draw a real schematic, staring at a breadboard with wires is an extra complication. Also, if you print the schematic on paper, you can make extra notes of voltages and currents measured.

It is possible to boost it with external transistors but that should not be needed for indoor experiments, so again: Read the datasheet and how the LED current is set.

Also do an experiment with the LED’s you have. How bright are they for a particular LED current?

Especially old leds have very low luminescence for a given current, as technology was not as advanced back then.

If you’ve devised a method to use external transistors to boost the current, and it does not work, then post the schematic (or the whole project) here and plenty of people will jump in to give some advise or help.

How much do you know about transistors (how they work and different types?) I suspect you’re just starting with all this electronics stuff.

I feel somewhere like would be a better place to ask your question. A hint if you don’t want to have your skin flayed off by the regulars there: Provide all relevant details like a schematic and values for your supply voltage, and component values.

About those LED tapes, if they’re anything like the reel I have, the are in sections comprising 3 LEDs in series with a current limiting resistor and are intended to be driven at 12V using PWM for dimming if desired.

Hello again Stan,

Both @paulvdh and @retiredfeline mention the need for a schematic.

If you ever need help drawing a schematic, this is the right forum for that! :grinning:

This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.