R1+. K. R K. PAGE. OF. TITLE. DATE. FOR PCB: $Date: (Sat, 09 Apr ) $. $Revision: $. CMoy Pocket Amplifier. 1. impressions, were so pleasant that I drew up a PCB layout subsequently and built one for a . This also allows the use of the same PCB as the CMoy-Linkwitz due to their similarities. .. portal7.info pdf. Ever wanted to build a CMOY using modern parts? This project uses http:// portal7.info (opens PDF). Attached Files.
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I searched the web for a CMoy (Chu Moy) audio amp PCB that would be easy to A zip file containing the EAGLE schematic files including PDF files of the PCB, . Founder's Remarks. The concept of the Bass Boost cMoy began in the summer of when I took an The cMoyBB's PCB has undergone numerous revisions. Crystal CMoy Free Form Headphone Amplifier: This headphone amplifier circuit is SCH Schematic and PDF below Crystal Cmoy Sch EaglePCB portal7.info
See O2 Resources below. The results were published in the first O2 article. Some of the competition would rather make vague and sometimes even misleading claims leaving you to wonder. And a lot of amps only work well with some headphones but are a poor match with others. The O2 comes close to a one-size-fits-all portable amp. For the history see the first article covering the premise , and the second article discussing the design process.
Thanks to the excellent step by step instructions written by Tangent I managed to get my way through building it. It sounded terrific, a noticable improvement from what I had been hearing directly out of my headphone jack. My first amp.
A Cmoy in an Altoids Original tin. Sadly, I fried the op-amp in the Cmoy the little chip inside that does all the work after listening to it for 6 months. Refusing to go back to the headphone jack, I took it as an opportunity to build another amp—perhaps one a little more advanced. It was designed specifically for Grado headphones which immediately sparked my interest.
Grados are different from most high-end headphones in that they have a relatively low impedance 32 Ohms. Most others are in the hundreds of Ohms. Top of the line Sennheisers run as high as Ohms.
This can change the sound quality rather than the volume—an important distinction. The Apheared 47 uses a two stage opamp approach that improves current handling.
There are four opamps in the A two for the left ear and two for the right. The rest of the circuit is very similar to the Cmoy. Apheared had only provided a schematic of the amplifier circuit with no mention of power supply requirements etc. This second thread produced tons of useful information about the power supply requirements and general design of the amp. Specifically, the Cmoy suffered from drift in the power supply that would cause the amp to become unstable and distort this is probably what ultimately fried my Cmoy.
If you read the thread you can see the suggestions made.
Basically, the resulting advice from the discussion was to add a TLE and a BUF to the power circuit that nails the voltages to their desired values. This provides a nice stable platform for the amp circuit to operate on.
This solution had the added bonus of making the power supply so stable that I could use a noisy power source like a DC wall wart plug to power the amp. For the Cmoy, I had to use a 9V battery and had to charge it once a week. If I used the wall wart with the Cmoy it would cause the opamp to oscillate and therefore distort and heat up.
The Plans When I first began to approach the circuit layout on an actual circuit board, I found that I was completely lost. Some people suggested that I use graph paper to lay out the circuit. I tried this, but every time I had to move something there was a heck of a lot of erasing involved.
Each time I updated the layout on the paper I became less sure that it would actually work. I broke down and postponed the build yet another week without tunes at work , and decided to make plans for this amp similar to the plans Tangent made for the Cmoy.
The result is below.
The instruction scheet I made for the A47 layout. Geometry comes more into play this way, and the way parts are manufactured, the number of leads, how they are organized all limit, and shape the way the parts can fit together. Some parts have 2 axial leads, others may have 2 or more linear leads or dual in-line leads, while another may have leads in a radial fashion.
Surface mount parts and through hole parts have different properties, but they can both work fine and can even be mixed in the same designs. When I used to work building electronics, engineers would revise designs, which would cause changes in manufacturing.
We would do things like clipping a lead on a part, solder a different part on to that one, or sometimes on top of another part. It was pretty common practice to piggyback memory modules or chips to make a bigger memory module or chip. This sort of thing is practical and viable in many useful ways.
Its also can be aesthetically appealing, and interesting looking. The purpose of this instructable isnt to show you how to do this, but rather that its a fun way to build interesting electronic projects, as well as a quick way to see if your thing works. Step 1: Piggybacked shift registers Shift registers are component often used in digital circuits, in this case, im using 74HC shift registers, they are very popular among hobby electrics users. They are a serial to parallel device, you send it a series of data, it outputs in a parallel fashion.
Serial parts work well for piggybacking, typically the outputs are parallel, and the input is chained from one chip to the next, with several leads in common. The leads that are common, can be soldered in a direct line, that makes things easy, the outputs are also in a direct line, which makes thing nice and easy.
The data chain is a simple repeating connection between one chip and another.
Fitting it together in a stack isnt usually all that much of a challenge, but it can be. Im usually using shift registers with LEDs, which means they often output to resistors, which can complicate things, but it can also make for more interesting designs. Stacking is by no means the only way to do this. It also illustrates how the parts work together to make one big part, like a hotel with many floors and many rooms on each floor.
LED cubes often use this style of building circuits in 3D space.
They work nice in a linear design too, as you can also see in a couple images. LED cubes typically use a common plane, and that plane also works as a physical structure that holds the shape of the cube together.
LEDs often work good for points, lines, matrices, and cubes. I have another instructable about building an LED cube. A fiber optic display that used some freeform electronics for the LEDs.
I needed a 3. I didnt want to run them at 5v, I wanted to see if I could get the voltage close to the LEDs forward voltage, to see if I could safely run LEDs with no current limiting resistor. Things didnt work out well, but building the test circuits went very well.
I started with a need for 3. I took a couple minutes to look through the data sheet to read the specs, and found some sample circuits. I noted the components in the samples, and looks at the circuit board with the voltage regulator, all those same parts were nearby, so I removed those parts also.
Then it was just a matter of putting the parts together in the right way, which I was able to do without a circuit board. The first photo shows where I found all the parts next to the completed regulated power supply.
The second photo shows how everything fits nicely together, and one of the output leads with a loop at the end for easy access.