by Petre Petrov @ electronicdesign.com:
The bipolar NE555 timer IC is widely used in inductorless dc-dc converters, most frequently in doubling and inverting converters. However, another very popular IC, the LM386 audio amplifier, may be a better solution in this application. Note that the results also depend on the specific manufacturer of these multisourced ICs and on the quality of the related components. (We will use only Schottky diodes, to reduce the voltage losses to the minimum.)
Comparing the NE555 Timer and LM386 Amplifier as Inductorless DC-DC Converters – [Link]
The Mini Audio Amplifier project is a good choice for battery operated gadgets. It is based on Texas instruments LM386 IC, provides high quality Audio.
– Wide power supply input 6 to 12 VDC
– 500 mW output @ 8 Ohms load
– Takes standard audio signal as input
– Low quiescent current drain 4 mA IC
– The quiescent power drain is only 24 mW when operating from 6 VDC
– Onboard preset for volume adjust
– Header connector for connecting power supply, audio signal and speaker
– Onboard power indication LED
– On/Off PCB mounted slide switch for power supply
– Four mounting holes of 3.2 mm each
– PCB dimensions 41 mm x 41 mm
Mini Audio Amplifier – [Link]
3 Tone Siren project produces Gun Sound, Police Siren and Ambulance Siren effects from a speaker. This project is built around UM3561 IC driving an LM386 audio amplifier to give that extra punch.
3 Tone Siren – [Link]
3 Tone Musical Bell is a project built around BT66T (UM66) IC driving, LM386 has been used as audio amplifier to give extra punch.
3 Tone Musical Bell – [Link]
by Petre Petrov:
This simple, robust, and low-cost signal generator, based on the LM386 power amplifier IC, provides a trio of audio-band signals with three different simultaneous outputs at the same frequency: square/rectangle (SQW), triangle (TRG), and sine (SS).
Audio Function Generator Provides Three Simultaneous Square, Triangle, Sine Waveforms – [Link]
Hack a Week’s new project this week is a single NPN transistor audio preamp – [via]
Here’s a great little project that goes well with the LM386 audio amp. It’s a good first time transistor project because it’s simple and demonstrates the common emitter class A amplifier circuit with only six components in the signal path.
The single NPN transistor audio preamp – [Link]
Due to its simplicity (requires minimum external components) and high availability, LM386 is very popular among hobbyists for use in low-voltage audio amplification applications. Most of the time a potentiometer is used at the input side of LM386 to provide a volume control in the output soundbar speaker. The potentiometer does not control the gain of the amplifier itself, but it creates a voltage divider network at the input, which in fact controls the fraction of the audio signal that is fed to the amplifier. This project is about a stereo audio amplifier using two LM386 ICs with digital volume control for both left and right speakers. So, how would you control the volume digitally? You are right, by replacing the traditional electro-mechanical form of potentiometers with digital potentiometer chips. This project uses MAXIM’s DS1868 dual digital potentiometer chip and a PIC microcontroller to control the volume of a stereo output from two LM386 ICs.
LM386 based stereo audio amplifier with digital volume control – [Link]
While LM386 is very popular among hobbyists, it provides the limited output power of only 1 Watt, and for stereo application, two LM386 ICs are required. This project is about making a 5 Watt stereo audio amplifier using the UTC TEA2025 IC chip.
TEA2025: An stereo Audio Amplifier IC – [Link]
This project described a stereo audio amplifier using two LM386 ICs and a PIC microcontroller to control the volume of the two output speakers. The project uses a DS1868 digital potentiometer that creates a voltage divider network at the input stage of LM386 to control the fraction of signal fed to the amplifier. The potentiometer wiper position is varied digitally by the microcontroller based on the user inputs.
Digital volume control for a stereo audio amplifier – [Link]
I love the LM386. It’s a complete amplifier in an 8 pin DIP chip! All that is needed to build an audio amp are a few external components most of which are decoupling capacitors. It is well suited to low power applications and runs just fine on a 9 volt battery or any voltage supply from 4-12 volts. It has a low quiescent current drain of only 4mA so it won’t kill a battery right away if you leave it on and idle. The gain is internally set to 20 but the addition of an external resistor and capacitor between pins 1 and 8 will increase the gain to any value from 20 to 200. An increase in bass frequency can be facilitated by adding a 10K resistor and .033 uf capacitor in series between pins 1 and 5.
The 1/2 watt LM386 Audio Amplifier – [Link]