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Chip Amps Amplifiers based on integrated circuits

LM 3886 18v at output
LM 3886 18v at output
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Old 16th November 2019, 09:32 PM   #1
nickalpha is offline nickalpha  Jamaica
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Default LM 3886 18v at output

i am having a serious problem my gainclone amp is outputting 18 volts measured from pin 3 and pin 7 (ground) what is it i am doing wrong
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Old 16th November 2019, 09:48 PM   #2
6L6 is offline 6L6  United States
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LM 3886 18v at output
Post some well-lit, in-focus photos of your build and the exact schematic you are using.
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Old 16th November 2019, 09:52 PM   #3
adason is offline adason  United States
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3886 is robust chip amp, it has all sorts of protection.
But no protection from wrong wiring.
Post schematics you are following. Post pictures, lots of it, high quality. We may be able to spot something. I have seen people use single supply with no cap on the output...then they wonder why it does not work.

Last edited by adason; 16th November 2019 at 09:58 PM.
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Old 16th November 2019, 10:09 PM   #4
edbarx is offline edbarx  Malta
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I will soon build two amplifier channels using this chip when my order arrives home. The PCBs have been made quite neatly using the acetone toner transfer method and a solution of hydrogen peroxide plus muriatic acid as etchant. The remaining step is to carefully inspect all the tracks for minute shorts with a magnefying glass. After that, I will check that the PCBs comform with the chip's pinouts. Misplaced schematics in the internet are not an impossibility.
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Last edited by edbarx; 16th November 2019 at 10:20 PM.
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Old 16th November 2019, 10:21 PM   #5
nickalpha is offline nickalpha  Jamaica
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I am using the data sheet schematics on perfboard
Attached Files
File Type: pdf lm3886-manual.pdf (279.1 KB, 32 views)
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Old 17th November 2019, 12:39 AM   #6
Mark Tillotson is offline Mark Tillotson
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Have you measured the voltage rails? Voltage on the feedback resistor?
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Old 17th November 2019, 01:33 AM   #7
nickalpha is offline nickalpha  Jamaica
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no i did not measure the voltage there i am suing a 20k feedback resistor
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Old 17th November 2019, 01:38 AM   #8
nickalpha is offline nickalpha  Jamaica
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i measure the voltage across the feedback resistor i got -2.5 mV
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Old 17th November 2019, 08:32 AM   #9
Mark Whitney is offline Mark Whitney  Netherlands
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Without photos it is going to be very difficult to workout what you have done wrong.
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Old 17th November 2019, 11:50 PM   #10
nickalpha is offline nickalpha  Jamaica
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Hey Guys thanks very much for your replies. i finally figure it was my PSU the bridge was wrong give 33 and -8 so i replace the bridge and it work!!!!!
i fried one of my chips though lol
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