We have audio

A project log for Marvin the Paranoid Doorbot

A Hitchiker's Guide-inspired door greeter for our local hackspace

JarrettJarrett 03/28/2014 at 19:530 Comments

I took some time out to wire up a quick audio amp.

Sound quality isn't really a huge concern here, so I just grabbed a LM1875 and used an example circuit from the datasheet.

I left National Semiconductor's name in the footer please don't sue me

I wanted to get this portion done as quickly as possible, so I found a perfboard kicking around the hackspace and deadbug soldered all of the components directly to each other. I have so much affection for this method, look at this fucked up board! It's like owning a pug that runs into walls.

One of the advantages of this method is that it's very very fast. The disadvantages are that it's terrible, it looks terrible, it's very difficult to troubleshoot if something goes wrong, and the weird ground loops are probably causing some audio problems. But you know what? That all adds character. This project is going to have a lot of character.

Fun story: I wired this up in an hour or so, then went over to our power station to test it out. It's rated for up to 60v, but I was pretty sure that'd be a little much. So I set the power supply to 12v, grabbed a function generator, and set it to 1kHz.

I touched it to the input, and it nearly blew me across the room. It's pretty loud.

So here's where we're at for the amplifier. I just attached the speaker with some double-sided tape.

Next step for me is to design the power supply.