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hoanganhnh
Joined: 26 Jun 2007
Posts: 7
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 28 Apr 2008 4:26 telephone recording, help me! |
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I'm working in the project "Telephone recording 4 channels".
I'm using the LM386, but I have some troubles.
When I test the board, I hear very much the noise.
Can you help me. I want to replace LM386 with other ICs.
Thank you very much
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Iouri
Joined: 17 Aug 2005
Posts: 685
Helped: 78
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| 29 Apr 2008 18:36 telephone recording, help me! |
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| LM386 it is not reason for the noise. post schematic here for review
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gerilla
Joined: 08 May 2008
Posts: 7
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| 08 May 2008 12:37 Re: telephone recording, help me! |
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| hoanganhnh wrote: |
I'm working in the project "Telephone recording 4 channels".
I'm using the LM386, but I have some troubles.
When I test the board, I hear very much the noise.
Can you help me. I want to replace LM386 with other ICs.
Thank you very much |
Hi. I wont tell much since my english is not enogh well.
I didn't see your circuit but You can separate your phone line and circuit's ground using transformer. Using phone line's ground could case noise but I am not sure if this will work.
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sabeti_1990
Joined: 16 Nov 2007
Posts: 65
Helped: 4
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| 20 Jun 2008 13:21 Re: telephone recording, help me! |
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hi body
for each phone line use a blue chock (with 16*19 EI & 300ohm in primery & 2*80 ohm in secondary) use secondary with a 100nf cap in seri to reccive sound if line & in primery give your sond
note: don't use 10uf cap between pin 1 & 8 of lm386
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the_risk_master
Joined: 12 Aug 2005
Posts: 698
Helped: 59
Location: UE+MIT, Philippines, (14°N , 120°E )
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| 20 Jun 2008 14:17 Re: telephone recording, help me! |
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Well, you did'nt bring up your circuit for detailed discussion here...
I'll just have a suggestion to replace LM386 with OPA2134UA, this is 0.0008% distortion, and ulta-low noise at 8nV/√Hz, what can you say huh
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sabeti_1990
Joined: 16 Nov 2007
Posts: 65
Helped: 4
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| 25 Jun 2008 7:52 Re: telephone recording, help me! |
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hi the_risk_master
it's good but in phone solution it's not necessary & lm386 is work good but your idea is too good
(in next week I let a sch for this application ok ?) 
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