The EasyEDA "Tesseract" DIY Guitar Practice Amplifier is an LM386 based low power amplifier designed to deliver up to about 500mW into an 8 Ohm speaker when run from a 9V battery. **Tesseract can be heard on YouTube here:** >https://youtu.be/9XzodyefyV8 The design given here - which includes a complete PCB design and Bill of Materials - is highly flexible and allows the several options in both the build and use of the amplifier. As well as a clipping circuit that some other designs - such as the more well known Smokey, Little Gem, Ruby and Noisy Cricket - have incorporated, Tesseract has several unique effects features designed into it: * Selectable Bipolar or Junction FET input stage for different input overload effects; * Adjustable gain and clipping 'hardness' in the Distortion stage; * An adjustable fullwave rectifier stage, driven by the distortion output, that generates a type of fuzz and frequency doubling effect called 'Wreckage'; * An optional low frequency oscillator stage to sweep the `Wreckage` effect; * A simple mixer to blend the 'Wrecked' and the 'Distortion' outputs; * Selectable, adjustable low or high frequency boost (a type of tone control); * An important aspect of the design is that all the features and FX can be tweaked for your delight and delectation. * Most features are also optional and can be wire linked out if not required without affecting the other functions. * The design could easily be modified to suit the LM380 2.5W or LM384 5W amplifier chips (although the Boost function would have to be omitted) or a range of other devices. * The design also includes a headphone output jack. * The PCB includes dual footprinting to simplify the choice of some of the components. * All parts (excluding the PCB) are available from: http://www.bitsbox.co.uk/ (Bitsbox can also supply suitable small switches, loudspeakers and battery holders or clips.) An alternative for J1 as an MPF102 is available from: http://www.tandyonline.co.uk/components/semiconductors/transistors/mpf102-jfet.html * Simulations of the different stages of this amplifier - and a copy of the EasyEDA LM386EE spice model used in them - can be found here: >https://easyeda.com/example/Tesseract_Guitar_Practice_Amp_simulation_files-H0ca8IFDB **To order Tesseract PCBs direct from EasyEDA** Sign up for a **free** account at: https://EasyEDA.com then click on 'Fork' or 'Open in Editor' in the upper right of this page and then click on the **Fabrication Output...** button on the top toolbar of the PCB layout tab: ![Fabrication Output...][1] Then click on the **Save To Cart** button on the **Add To Cart** page: ![Save To Cart][2] Then follow the instructions on the **Home > My Account> Cart** page. Orders can be tracked on the **Home > My Account> History Orders** page. **To download Gerbers for 3rd party PCB fabrication** Click on 'Open in Editor' in the upper right of this page and then click on the **Fabrication Output...** button on the top toolbar of the PCB layout tab: ![Fabrication Output...][3] Then click on the **Download Gerber Files** button on the **Add To Cart** page: ![enter image description here][4] * **Please note that this project is subject to the CC-BY-NC-SA 3.0 license.** For more information please see: >https://creativecommons.org/licenses/by-nc-sa/3.0/ [1]: /editor/20150921/55fedb38c046a.png [2]: /editor/20150921/55fedd63a9390.png [3]: /editor/20150921/55fedb38c046a.png [4]: /editor/20150921/55fedc3db4ced.png