making a amplifier with a lf 351n

Discussion in 'Analog & Mixed-Signal Design' started by johanispro3, Sep 25, 2016.

  1. johanispro3

    Thread Starter New Member

    Sep 25, 2016
    This is my first post on this forum, I'm new to electronics but eager to learn
    I have a big interest in audio and I want to make an amplifier for a 8ohm 0.5W speaker I have lying around, if I connect it directly to the audio jack of my phone
    it barely makes any sound. So after some research I discovered I need an amplifier IC. So after hours of digging around on old pcb's I found a chip. An LF 351N. The datasheet gives says it's an op amp, but for circuitry I could only find some exemplary uses on the datasheet. I found a circuit for an inverted amp, will an inverted amp be suitable for listening to music? Anyway, I'm looking for a cicruit for this chip to make an amplifier. All help is appreciated.
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
    You wont make a loud noise from that chip, you're better using a Lm380...
  3. MrChips


    Oct 2, 2009
    It is correct to say that you need an amplifier but all amplifiers are not created equal. What you need is a power amplifier.

    An op-amp (operational amplifier) is the generic term for an idealized type of amplifier.
    An ideal amplifier has some desired characteristics:
    • Infinite input impedance
    • Zero output impedance
    • Infinite voltage gain
    • Infinite band-width
    No such op-amp exists.

    What you are looking for is a power amplifier designed to drive an 8-ohm speaker with a certain amount of power (0.5W as you requested) with a frequency range in the audio range 20-20kHz.

    LM380 is one example of a low power audio amplifier.