Monday, December 22, 2014

4W Amplifier With LM383

This post is about an amplifier with wide voltage range and moderate power output.

Where to use?

1. With a desktop computer as a cheap speaker, you can just hook up the speaker directly with your computer power supply unit saving you the cost of making a power supply unit.

2. Where bass is not much of a concern.

3. Can be used with Sealed lead acid battery or lithium battery so portable.

4. Can be used in automobile. 

What's good about the design?

1. Requires only a few external component.

2. Can be operated from a wide voltage range of 5V to 20V. Although at 5V it will only produce about 1W which is not that practical but at 12V it produces around 4W on 4‎Ω load which I think is the sweet spot.

3. Circuit is pretty easy to design.

4. Can be powered directly from Car Battery or a 19V Laptop charger.

Components needed: 
(For Mono Amplifier) 

1 2200µF
1 1000µF
1 470µF
1 10µ
2 0.22µF

1 1Ω

Power OP-AMP:
1 LM383 + Heat Sink


The Diagram


1. Use 25V Capacitor for 12V Input and 35V for 20V Input.
2. Make another Identical one to get Stereo.
3. You can add a 50kΩ variable resistor to control the volume.
4. You might omit the 1000µF capacitor if your power supply already have one.
5. Changing the 2200µF capacitor to 1000µF will reduce the lower frequency. 
6. Solder the 0.22µF capacitor of the Output section as close as you can to the Pin 3 and 4. 
7. Make sure to assemble in good quality PCB with proper Grounding.
8. Low impedance speakers will yield higher power at the expense of distortion.
9. Higher Input voltage will yield higher power but 20V must not be crossed.
10. Read the Datasheet for more information.


Datasheet of LM383
Index to my blog.

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