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
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
- Used SIP-x instead of PIN_ARRAY_xX1 parts so the headers have holes that are too small.
- IN/OUT silkscreens are backwards.
- J3 close to IC.
- Placement of parts did not allow a 5mm TB to be used for the power input.
- C3 part was 11 mm but the parts I bought were 8 mm.
V2 - Fixes
- Made RV1 and J3 holes bugger (switches from SIP-2/SIP-3 to PIN_ARRAY_2X1/PIN_ARRAY_3X1.
- Swapped IN/OUT silkscreen.
- Moved J3 further away from IC.
- Replaced parts to allow 5mm TB to be used for power input
- Changed C3 part from was 11 mm to 8 mm.
V2 Issues
- Missing silkscreen on boards from LAEN.
-
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