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]
Today we did an project amplifier with LM386. This amplifier is very easy to make and very compact, works with a single power source whose value can be between 4V and 12V.It is based on the use of a type LM386 amplifier, capable alone to issue a power of several hundreds of milliwatts to a load (HP) of 8 ohms, while consuming only a few mA at rest. Ideal for make a small portable battery powered amp.For an application in stereo, just to build this amp in two examplaires.
Amplifier With LM386 - [Link]
Many electronic projects require the use of a small audio amplifier. Be it a radio transceiver, a digital voice recorder, or an intercom, they all call for an audio amp that is small, cheap, and has enough power to provide adequate loudness to fill a room, without pretending to serve a disco! About one Watt RMS seems to be a convenient size, and this is also about the highest power that a simple amplifier fed from 12V can put into an 8 Ohm speaker.
LM386 Amplifiers – [Link]
This project is an easy audio amplifier based on 8 pin DIP LM386 integrated circuit.
The potentiometer is the volume control. The heatsink is screwed to an LM7812 12V voltage regulator. There are a couple of caps and a diode on there. The wire with what looks like gum on the end of it is actually the headphones jack wire with a three-pin header molded onto the end using that really cool putty “as seen on TV” that you knead together and it forms really hard parts. I used it to protect the super-thin wires of the headphones jack. The little chip on that board is the LM386. The red- and black-tipped wires coming into the top of the breadboard just left of the diode and the voltage regulator are the leads from a Radio Shack 12V, 500 mA wall wart.
LM386 Easy Amp – [Link]
This project is a FM Radio basd on TDA7000 and LM386 integrated circuits. Schematic and PCB are available on the link below.
FM Radio Using TDA7000 and LM386 – [Link]
This circuit is a simple intercom circuit based on LM386 low voltage audio amplifier. It uses 8 ohm speakers that works as a microphone and as speaker at the same time. A 10k potentiometer is used to adjust the volume. It also has a double pole double throw switch that is used as push to talk switch.
Simple two way intercom – [Link]