Class 1


Today we talked about the general project idea: make a portable device that can play music. In summary, we are going to use the LM386 op-amp integrated circuit (IC) to make an input signal (eg. from your phone’s audio jack) strong enough that it can drive a speaker to play music. We are going to assemble the amplifier circuit on perf board which allows you to connect through hole components. The LM386, like most other ICs, needs a source of power to work. Our circuit will provide the necessary voltage with a 3.7v 18650 lithium ion battery. We will also need to do some “cleaning up” of the signal, which is called noise filtering, and that is what the other parts of the circuit do. We did not cover that in Class 1, but will go through in detail in Class 2.

We also discussed the design element of the project. Aside from the electronics, you will need to design an enclosure for circuit to go in, along with other features to make the project more interesting. These can be a user-interface (UI) such as a display and buttons, bluetooth functionality, RGB lighting corresponding with the frequencies of the music–the list goes on and on. As for the enclosure, I encourage you to be creative and don’t just think about the box, think outside it (I couldn’t help myself, sorry). One such example is DIY Perks’ concrete speaker. It’s a really cool design and material choice, and he also made excellent use of cheap, pre-assembled modules from the internet.


LM386 Data Sheet

This is the schematic for the LM386 op-amp. You can read the datasheet and watch this video for more information.

LM386 Pins

Mine so far

Mine So Far