The circuit is built around a popular Sanyos stereo head preamp IC LA3161. Low electrical signals from the playback heads are fed to pins 1 and 8 of IC1 via DC decoupling capacitors, respectively. Components between pins 2 and 3 and pins 6 and 7 provide adequate equalization to the signals for a normal tape playback.
Tape Head Pre-Amplifier - [Link]
This project is a message recording board capable of recording 120 secs of audio. This project is designed around ISD25120 which can store 120 Seconds audio. Recording and playback operations are controlled with tact switches. The kit has an onboard microphone and LED to indicate the functions of Play and Recording. IC has a re recordable non-volatile memory which means that the message will be stored even after the units are turned off and even when it is turned on again.
120 Seconds Voice Record – Play Back - [Link]
Rugged, great sounding boomboxes for all of life’s adventures.
DemerBox is a rugged, great sounding, water-resistant boombox that you can put things inside. The Bang is our single speaker model. Its about the size of a lunchbox but don’t let its svelte size fool you. The Bang gets loud, has tight punchy bass, and pleasing mids and highs. The Big Bang is our two speaker model. Its about the size of a soccer ball. The Big Bang gets louder than The Bang, and because it has two speakers, you get stereo separation and a little more detail in the music.
DEMERBOX – Rugged Wireless Boomboxes - [Link]
Bastl3r wrote this instructable detailing the build of his guitar booster pedal project:
I chose an overdrive pedal design off of generalguitargadets.com (Schematic) and modified it like this:
added a simple positive/middle/negative supply
added a noise filter I found on beavisaudio.com right after the DC Jack (Huminator)
took away the clipping diodes on the output
connected the diodes in the feedback path directly
added the switch to change the resistance of the feedback path (10k <->30k)
Guitar booster pedal (MPX-1) - [Link]
Rupert Hirst writes:
A long awaited refresh, to my previous “Anti Thump” headphone output delay circuit, designed back in 2011.
The Idea behind the circuit is to introduce a small delay, during initial power up, to electrically isolate and protect equipment connected directly to an amplifier. Often, during power up, amplifiers can produce an audible thump, through speakers or headphones. This can lead to damage of the connected equipment over time.
Thumps and clicks will occur when the supply rails voltages are too low to allow the amplifier to control its output voltage.
As the circuit has an immediate disconnect when powered off, most instances of turn off thump are also dealt with, such as output capacitor discharges.
Audio: Headphone “Anti thump” delayed output rev 1.1 - [Link]
Most of the work that I have done in the past with vacuum tube and solid state electronics has been repair. So, I have ventured into the realm building. This is actually my second build (I’m still getting the bugs out of the first attempt) but I have applied all that I learned from mistakes to this build. Building from scratch is nothing like repairing. It takes time, a lot of thought and reasoning go into a build no matter how simple it may look.
6v6 Stereo Amplifier - [Link]
by Giovanni Militano @ diyaudioprojects.com:
I’ve always enjoyed electronic kits of all kind and like many of you will credit them for the foray into DIY audio. Over time as my DIY skills matured I found myself taking the DIY route for projects far more often than relying on kits. While I will always enjoy electronic kits, I generally won’t try one out unless there is something really unique about the kit. When I saw the Gobo Stereo Audio Amplifier kit from boxedkitamps.com, I was immediately intrigued by the unique looking enclosures available with the amplifier kits. Shown in Photograph 1 below is the completed Gobo Stereo Audio Amplifier kit with a translucent blue acrylic enclosure. The choice of enclosure finishes for the Gobo stereo amplifier kit include blue, dark grey and orange acrylic and bamboo.
Gobo Stereo Audio Amplifier Kit (LM1875, 15W, Class-AB) - [Link]
Here’s a cool Mini LED volume towers project by Ben Finio. He writes a complete step-by-step instructions here:
The inspiration for this project started when I saw a variety of awesome stereo LED towers on YouTube (also referred to as VU meters). Many of the videos showed the end result, and maybe a slideshow of the assembly process, but lacked complete build details or a circuit diagram. So, I set out to find out how they worked, and build my own “mini” desktop version that would go nicely with computer speakers, instead of a big living room stereo. This Instructable will give you complete directions to assemble the required circuit (even if you have no electronics experience – you can even do it without soldering), build two LED towers, and hook them up to an audio input so you can simultaneously drive them and listen to music.
Mini LED volume towers (VU meters) - [Link]
The amplifier is based on the 12AU7 valve (part number ECC82 in Europe). The schematic came from here, it’s a nice kit, but lacked a power supply and the layout wasn’t quite what we needed for kits in TinkerSoc. I added a LDO 12v regulated power supply, an input volume control pot and kept the design single layered (with one jump). The final schematic can be viewed here
Tube Amplifier - [Link]