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audio power amplifier circuit lm3886

Konusu 'Amplifikatör Devreleri' forumundadır ve guclusat tarafından 1 Aralık 2009 başlatılmıştır.

  1. guclusat
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    guclusat Tanınmış Üye Süper Moderatör

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    14 Haziran 2009
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    Circuit audio power amplifier of 68 watts using lm3886

    The lm3886 is an integrated circuit very used in projects of audio amplifiers by that it can be found with more easiness.


    see that the circuit should be fed by source symmetrical good filtered of + 34 and – 34 volts. R2 and L1 is a resistor of 10 ohms / 2watt coiled with 10 to 12 you exhale of enameled thread AWG 20. The circuit integrated lm3886 is a component easy of being found at the electronics stores, for that he is used in several projects of potency audio, some exist circuits with linked lm3886 in bridges for potencies of up to 150 watts. For most information on the assembly of that circuit, I suggest that sees the datasheet of the lm3886 in the site of the national semiconductors. With the information of the leaf of data you can adapt the circuit with lm3886 your needs.
    [​IMG]
    suggestion of printed circuit board for assembly of the power amplifier

    [​IMG]
    Board for assembly seen beside the components power amplifier lm3886

    [​IMG]
    It lists of components for assembly of the power amplifier

    R1 10K Ohms

    R2 10 Ohms 2W sees text

    R3 10 Ohms

    R4 47K Ohms

    R5 220K Ohms

    R6 10K Ohms

    R7 100K Ohms

    C1 100NF

    C2 100NF

    C3 100NF

    C4 100UF

    C5 100UF

    C6 4,7UF

    C7 100UF

    C8 1UF

    L1 0,7uH sees text
     

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    Son düzenleme: 20 Mart 2013
  2. guclusat
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    guclusat Tanınmış Üye Süper Moderatör

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    Power Amplifier with LM3886

    PA100-schematic-diagram.gif



    LM3886 entegresi ile yapılmış farklı bir devre daha
     
    Son düzenleme: 21 Eylül 2016
  3. guclusat
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    guclusat Tanınmış Üye Süper Moderatör

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    This is 100W LM3886 power amplifier is based on the PA100 parallel amplifier detailed in National Semiconductor's application note - AN1192. Since my DIY speaker is 4-ohm and somewhat difficult to drive, I want to have a more powerful amplifier to match with it. Therefore I designed this amplifier which uses two LM3886 per channel, in parallel circuit. This amp can deliver about 50W into a 8-ohm speaker and 100W into a 4-ohm speaker. This is a stereo amplifier and therefore 4 LM3886s are used. The LM3886 circuit is in a non-inverted configuration, so the input impedance is determined by the input resistor R1, i.e. 47k. The 680 ohm and 470pF resistor capacitor filter network is used to filter out the high frequency noise at the RCA input. The 220pF C4 and C8 capacitors are used to shot out the high frequency noise at the LM3886 input pins. I used high quality audio grade capacitors at several locations: 1uF Auricap at the input for DC blocking, 100uF Blackgate for C2 and C6, and 1000uF Blackgate at the supply filter.


    PA100_schematic.gif

    The PCB is designed in a way that the power ground is separated from the signal ground, as you can see from the below layout. The signal ground is located in the middle and surrounded by the power ground. There is a thin trace near C5 connecting them. The PCB layout is done by using PADS PowerPCB 5.0. I think it is a powerful layout software. After finished the layout, I send it to a PCB manufacturer in HK to make the PCB. After the PCB is made, I found some of the drill holes are not large enough.... I have to make it bigger manually.
    Finished PCB.

    The 20k and 1k resistors are hand matched to 0.1%. For the output resistors, I used six 0.5W 1% 1ohm resistors in parallel per 3886 output instead of one 3W resistor because 3W 1% resistors are hard to find.

    I used the insulated version - LM3886 TF, so that I can mount it directly to the case and heat sink with thermal compound.


    Coupling capacitor is Auricap 1uF 450V. I used this high quality capacitor because it is in the main signal path.

    The HF filter capacitors are Silver Mica 47pF and 220pF.

    The power supply filter used is Blackgate 1000uF 50V.

    C2 and C6 are Blackgate 100uF 50V. For better result, the bi-polar version should be used. However I am not using it because the bi-polar blackgate is too big to fit into my PCB.

    The 680 ohm + 470pF filter network is installed at the RCA. This help filtering the high frequency noise before it gets onto the board.

    The WIMA 0.1uF supply decoupling capacitors are soldered directly on the pins of LM3886 at the back of the PCB. This helped to remove some high frequency noise.

    The 3886 are mounted on a 3/8 inch aluminum plate then to the case. Outside of the case I used 3 PC CPU heatsinks. I used Arctic Silver thermal compound between the aluminum layers to improve heat conductivity.

    With all these big heatsinks, it only get slightly warm when listen at normal volume.

    The power supply used is a regulated power supply. I used 10000uF per rail before the LT1083 regulator. After the regulator, I have 100uF on the regulator board. The advantage of using regulator is that the power supply ripple voltage is removed. If power regulation is not used, I can hear very little 50/100Hz hum from the speaker.
     
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Benzer Konular - audio power amplifier
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