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AudioAmp386

Page history last edited by MrTundraMan 11 years, 1 month ago

Audio Amplifier LM386

 

 

Description of the Design

 

Purpose is to have an audio amplifier for use with a Theremin.

 

This is a pretty simple example of the LM386 more or less right off the datasheet.

 


 

LM386 parts are available in several power output options and put out about 3/4 W at 12V.

 

Front and back ends are both AC coupled so there's no concerns with DC biasing.

 

Connectors

 

  • RCA jacks for input/output to match "normal" cables easily available.
  • J1 = RCA Input
    • Center = signal
    • Shell = ground
  • RV1 - 0.1" 3 pin pot connection to allow easy wiring to the High Voltage Digital Pot design or an external pot.
    • 1 = Signal In
    • 2 = Wiper/Signal Out
    • 3 = Ground
  • J2 = RCA, Output 
    • Center = signal
    • Shell = ground
  • J3 - Power connector
    • Pin 1 = 12V
    • Pin 2 = GND

 

Parts List - V2

 

Desc Qty Pkg RefDes Mfg MfgPN Vendor VendorPN
.047uF 1 C1 C2 Kemet C316C473M5U5TA Mouser 80-C316C473M5U
0.1uF 1 C1 C1 Vishay 1C10Z5U104M050B Mouser 75-1C10Z5U104M050B
10 1 R1 R1 Vishay CCF0710R0GKE36 Mouser 71-CCF0710R0GKE36
10K 1 PIN_ARRAY_3X1 RV1 FCI 68001-203HLF Mouser 649-68001-203HLF
220uF 1 C2V8 C3 United Chemi-Con EKMG250ELL221MHB5D Mouser 661-EKMGG250ELL221MH
CONN_2 1 TB2-5MM J3 TE 282836-1 Mouser 571-282836-1
LM386 1 DIP-8__300 U1 National Semi LM386N-3/NOPB Mouser 926-LM386N-3/NOPB
MTG-4-40 2 MTG-4-40 MTG1, MTG2



RCA-JACK 2 RCA J1, J2 Neutrik NYS354 Mouser 568-NYS354

 

Mounting Holes

 

Two 4-40 mounting holes allow the card to be mounted vertically on two support screws using a simple L bracket.

 

Versions

 

V1 Issues

 

 

 

  1. Used SIP-x instead of PIN_ARRAY_xX1 parts so the headers have holes that are too small.
  2. IN/OUT silkscreens are backwards.
  3. J3 close to IC.
  4. Placement of parts did not allow a 5mm TB to be used for the power input.
  5. C3 part was 11 mm but the parts I bought were 8 mm.

 

V2 - Fixes

 

  1. Made RV1 and J3 holes bugger (switches from SIP-2/SIP-3 to PIN_ARRAY_2X1/PIN_ARRAY_3X1. 
  2. Swapped IN/OUT silkscreen.
  3. Moved J3 further away from IC.
  4. Replaced parts to allow 5mm TB to be used for power input
  5. Changed C3 part from was 11 mm to 8 mm.

 

V2 Issues

 

 

  1. Missing silkscreen on boards from LAEN.
  2.  

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