Difference between revisions of "AudioAmp380"

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[[FILE:AudioAmp380-3D.png]]
 
[[FILE:AudioAmp380-3D.png]]
  
== Design ==
+
== Design Features ==
  
 
* Pre-amp plus power amp
 
* Pre-amp plus power amp
* 50 Ohm input impedance
+
* 50 Ohm input impedance matches Product Detector outputs
 +
* 0-10x Gain trimmer potentiometer on preamp
 
* External mount gain potentiometer
 
* External mount gain potentiometer
** Gain potentiometer on preamp
+
* [https://www.ti.com/lit/ds/symlink/ne5534.pdf NE5534] Pre-amplifier
 
* [https://www.ti.com/lit/ds/symlink/lm380.pdf LM380] 2.5W Audio Power Amplifier
 
* [https://www.ti.com/lit/ds/symlink/lm380.pdf LM380] 2.5W Audio Power Amplifier
** Wide Supply Voltage Range: 10V-22V
+
* 12V nominal power
** Low Quiescent Power Drain: 0.13W (VS= 18V)
+
** 10-22V
** Voltage Gain Fixed at 50 (34 dB)
+
* Fits into standard 80x50x20mm extruded aluminum enclosure
** High Peak Current Capability: 1.3A
+
 
** Input Referenced to GND
+
=== Pre-Amplifier (NE5534) ===
** High Input Impedance: 150kΩ
+
 
** Low Distortion
+
* Low-Noise Operational Amplifiers
** Quiescent Output Voltage is at One-Half of the Supply Voltage
+
* Internally fixed gain of 50 (34 dB)
* [https://www.ti.com/lit/ds/symlink/ne5534.pdf NE5534] Pre-amplifier
+
* Equivalent Input Noise Voltage 3.5 nV/√Hz Typ
** Low-Noise Operational Amplifiers
+
* Unity-Gain Bandwidth 10 MHz Typ
** Equivalent Input Noise Voltage 3.5 nV/√Hz Typ
+
* Common-Mode Rejection Ratio 100 dB Typ
** Unity-Gain Bandwidth 10 MHz Typ
+
* Wide Supply-Voltage Range ±3 V to ±20 V
** Common-Mode Rejection Ratio 100 dB Typ
 
** Wide Supply-Voltage Range ±3 V to ±20 V
 
 
** Used as single supply
 
** Used as single supply
* Fits into 80x50x20mm extruded aluminum enclosure
 
`
 
  
== Schematic ==
+
=== Audio Power Amplifier (LM380) ===
  
[[file:AudioAmp380-Schematic.png]]
+
* Wide Supply Voltage Range: 10V-22V
 +
* Low Quiescent Power Drain: 0.13W (VS= 18V)
 +
* Voltage Gain Fixed at 50 (34 dB)
 +
* High Peak Current Capability: 1.3A
 +
* Input Referenced to GND
 +
* High Input Impedance: 150kΩ
 +
* Low Distortion
 +
* Quiescent Output Voltage is at One-Half of the Supply Voltage
  
== Rev 1 Rework ==
+
== Controls ==
 +
 
 +
* RV1 - trade-off gain/bandwidth - Tune for best sound
 +
* RV2 - volume control (after preamp and before LM380 Amp). 1x5 header wire to external pot
 +
 
 +
== Jacks ==
 +
 
 +
=== J1 - Audio In ===
 +
 
 +
* 50 Ohms input impedance for radio applications
 +
** Output of Product Detector stage
 +
** R1 = 51 Ω
 +
** RV2 = 500 Ω pot
 +
* Optional [https://en.wikipedia.org/wiki/Line_level#Line_in Line Level Input]
 +
** The impedance of a line input is typically around 10 kΩ
 +
** R1 = 10 kΩ
 +
** RV2 = 50 kΩ pot
 +
* RCA jack
 +
 
 +
=== J2 - Audio Out ===
 +
 
 +
*  8 Ohm speakers
 +
* RCA
 +
 
 +
=== J3 - Power ===
 +
 
 +
* 10V-22VDC
 +
* 5.5mmx2.5mm DC jack
 +
 
 +
== Measurements ==
 +
 
 +
* MHS-5200A Signal Generator
 +
** 200 mV
 +
** 100-10KHz
 +
** Drives 50 Ohms
 +
* Adjust Trimmer CCW for full gain
 +
** With adj screw to the right side
 +
* [[Benchtop Power Supply DPS3005]]
 +
** 12V
 +
** 20mA with volume control fully down
 +
** 300mA with volume control fully up (3.6W)
 +
 
 +
== Rev 2/3 Schematic ==
 +
 
 +
[[file:AudioAmp380-Rev3_Schematic.png]]
 +
 
 +
== Revision History ==
 +
 
 +
=== Rev 1 Rework ===
 +
 
 +
==== Rev 1 Schematic ====
 +
 
 +
* (Before rework)
 +
 
 +
[[file:AudioAmp380-Rev1_Schematic.png]]
 +
 
 +
=== LM380 Equivalent Schematic ===
 +
 
 +
[[file:LM380_Equiv_Schematic.PNG]]
  
 
* Issues
 
* Issues
** Front end opamp has + and - reversed
+
** Pre-amp opamp has + and - reversed
 
** Also hooked up the feedback to the wrong input
 
** Also hooked up the feedback to the wrong input
 +
* Replace R1 with wire jumper
 +
* Replace C9 with wire jumper
 +
* Remove C2
 
* 5 Cuts
 
* 5 Cuts
 
** 4 on front
 
** 4 on front
 
** 1 on back
 
** 1 on back
* 5 Jumpers on back
+
* 5 jumper segments on back
 +
** 2 nodes
  
 
[[file:U2-2_3_Rev1_Rev2_Cuts_Jumpers.png]]
 
[[file:U2-2_3_Rev1_Rev2_Cuts_Jumpers.png]]
 +
 +
* Jumpers on rear side
 +
 +
[[file:AudioAmp380_Back_Jumpers.PNG]]
 +
 +
=== Rev 2 ===
 +
 +
* Schematic C5 was 100uF, should be 100nF
 +
** Fixed on prototype
 +
* Footprint wrong on C2 (older rev 2 was ordered)
 +
** 10uF can be fit onto the card
 +
* Didn't have any 100uF cap to use at C9
 +
** Used 47uF - power bypass = OK value
 +
 +
=== Rev 3 ===
 +
 +
* Fixed C3 footprint already
 +
* Fixed C5 footprint back to 0.1" small cap footprint
 +
* Card works
  
 
== Videos ==
 
== Videos ==
 +
 +
* Charlie Morris ZL2CTM design
  
 
[[file:ZL2CTM_Schematic.PNG]]
 
[[file:ZL2CTM_Schematic.PNG]]
  
 
<video type="youtube">GlT0HbvcmrM</video>
 
<video type="youtube">GlT0HbvcmrM</video>
 +
 +
== Panel Cutouts ==
 +
 +
[[file:AudioAmp380_Panel_Cutouts_Rev3.PNG]]
 +
 +
* [http://land-boards.com/AudioAmp380/AudioAmp380_Panel_Cutouts_Rev3.pdf Panel cutout] (PDF File)
  
 
== Assembly Sheet ==
 
== Assembly Sheet ==
  
[[LM380 Rev 1 Assembly Sheet]]
+
* [[LM380 Rev 1 Assembly Sheet]]
 +
* [[LM380 Rev 2 Assembly Sheet]]
 +
* [[LM380 Rev 3 Assembly Sheet]]

Latest revision as of 20:36, 29 March 2022

AudioAmp380-3D.png

Design Features

  • Pre-amp plus power amp
  • 50 Ohm input impedance matches Product Detector outputs
  • 0-10x Gain trimmer potentiometer on preamp
  • External mount gain potentiometer
  • NE5534 Pre-amplifier
  • LM380 2.5W Audio Power Amplifier
  • 12V nominal power
    • 10-22V
  • Fits into standard 80x50x20mm extruded aluminum enclosure

Pre-Amplifier (NE5534)

  • Low-Noise Operational Amplifiers
  • Internally fixed gain of 50 (34 dB)
  • Equivalent Input Noise Voltage 3.5 nV/√Hz Typ
  • Unity-Gain Bandwidth 10 MHz Typ
  • Common-Mode Rejection Ratio 100 dB Typ
  • Wide Supply-Voltage Range ±3 V to ±20 V
    • Used as single supply

Audio Power Amplifier (LM380)

  • Wide Supply Voltage Range: 10V-22V
  • Low Quiescent Power Drain: 0.13W (VS= 18V)
  • Voltage Gain Fixed at 50 (34 dB)
  • High Peak Current Capability: 1.3A
  • Input Referenced to GND
  • High Input Impedance: 150kΩ
  • Low Distortion
  • Quiescent Output Voltage is at One-Half of the Supply Voltage

Controls

  • RV1 - trade-off gain/bandwidth - Tune for best sound
  • RV2 - volume control (after preamp and before LM380 Amp). 1x5 header wire to external pot

Jacks

J1 - Audio In

  • 50 Ohms input impedance for radio applications
    • Output of Product Detector stage
    • R1 = 51 Ω
    • RV2 = 500 Ω pot
  • Optional Line Level Input
    • The impedance of a line input is typically around 10 kΩ
    • R1 = 10 kΩ
    • RV2 = 50 kΩ pot
  • RCA jack

J2 - Audio Out

  • 8 Ohm speakers
  • RCA

J3 - Power

  • 10V-22VDC
  • 5.5mmx2.5mm DC jack

Measurements

  • MHS-5200A Signal Generator
    • 200 mV
    • 100-10KHz
    • Drives 50 Ohms
  • Adjust Trimmer CCW for full gain
    • With adj screw to the right side
  • Benchtop Power Supply DPS3005
    • 12V
    • 20mA with volume control fully down
    • 300mA with volume control fully up (3.6W)

Rev 2/3 Schematic

AudioAmp380-Rev3 Schematic.png

Revision History

Rev 1 Rework

Rev 1 Schematic

  • (Before rework)

AudioAmp380-Rev1 Schematic.png

LM380 Equivalent Schematic

LM380 Equiv Schematic.PNG

  • Issues
    • Pre-amp opamp has + and - reversed
    • Also hooked up the feedback to the wrong input
  • Replace R1 with wire jumper
  • Replace C9 with wire jumper
  • Remove C2
  • 5 Cuts
    • 4 on front
    • 1 on back
  • 5 jumper segments on back
    • 2 nodes

U2-2 3 Rev1 Rev2 Cuts Jumpers.png

  • Jumpers on rear side

AudioAmp380 Back Jumpers.PNG

Rev 2

  • Schematic C5 was 100uF, should be 100nF
    • Fixed on prototype
  • Footprint wrong on C2 (older rev 2 was ordered)
    • 10uF can be fit onto the card
  • Didn't have any 100uF cap to use at C9
    • Used 47uF - power bypass = OK value

Rev 3

  • Fixed C3 footprint already
  • Fixed C5 footprint back to 0.1" small cap footprint
  • Card works

Videos

  • Charlie Morris ZL2CTM design

ZL2CTM Schematic.PNG

Panel Cutouts

AudioAmp380 Panel Cutouts Rev3.PNG

Assembly Sheet