Magic Sing Karaoke Microphone Tear Down, Part 2

I’m back!  I have a tendency to pause projects for lengthy periods of time, so here is part 2 of my Magic Sing Karaoke Microphone Tear Down.  This time, we’re actually going to look inside the microphone, which serves as a remote control as well.

On the outside we see a nicely designed case with buttons, and an LCD screen.

Upon power up, the LCD reads “SYNC”.  When you turn on the base station, they connect and the LCD says “Karaoke” which is the default menu option.  The communications is two-way, what happens on the screen is reflected in the LCD.  When you enter a song # or browse for a song and select it, the song # is displayed.

Let’s open it up!  (Carefully)!

We see one lengthy PCB with a silver box on the end.  That silver box indicates RF shielding…So that means the radio is under that hood.

Confirmed!  These chips are a TI CC2400 transceiver (2.4ghz), an undocumented CASUH retaw1-05, and an SST 1Mbit flash chip.  The retaw1-05 is a RF modem chip, but could not find a datasheet on it.

The back of the radio board is boring, but has a couple of connectors.  Moving on…

How the two boards look when separated.  At the left side of the long board is an ATMEGA48.  It is right under the LCD so I’m going to guess it is the button/LCD controller.  I’m pretty sure we can assume that the Atmel also connects to the retaw1-05 radio modem chip.


They made a failed attempt at covering that ATMega48..

Below we can see the codec chip (AIC311). This chip is responsible for converting the audio from the microphone into a digital stream.  It has some other neat capabilities such as pitch changing, base, treble adjustments, etc. By the location, and the traces that run out to the right, I can extrapolate that this chip feeds directly into the bottom black connector going to the radio board.  The Atmega48 surely has some control lines going to this as well.

To Do:

It would be really neat if I could sniff the packets coming out of that CC2400.  I’m also not sure if both the RF Modem and the CC2400 are generating radio frequencies. The datasheet (two page only) that I could find on the Retaw says it is 2.4ghz but it also says it can interface with a CC2400.  There are many products from Korea that use this chip alone for both audio and data (phones, head phones, etc), so I’m a bit confused why they use both chips.

Magic Sing Karaoke Microphone Tear Down, Part 1

I bought this Magic Sing Karaoke microphone system many years ago and my family and friends have enjoyed and some times been annoyed by it quite often!  It truly is a really neat gadget..  I’ve got a plethora of photos of the inside, the outside and the on screen displays.

The microphone base has 2500 songs built in, and has several add on slots for song chips that are available online for about $60 a pop.

The base also has an SD card slot, but it is not for songs.  It is only used for storing user content, photos, backgrounds, movies and songs recorded live.

The system includes two cordless microphones that also each act as a remote control.

The model # I have is the ET19KV.  I originally paid $499 for it!  But that was like eight years ago!

Under the top cover of the base unit we find the slots for expansion chips.  I’m impressed by the number of slots.  Some song chips have 200, 400 songs!  But most have between 60 and 100.  The songs are of the MIDI type.  You can watch the video at the end of the article to hear the actual sound quality.


The rear of the base has the output connections:


The wireless microphone antenna:


Let’s open it up!  Don’t tell my wife!  At least I put it back and no extra screws were left!



Interesting things in here.  The big black parking lot sized chip on the left is an FPGA!  The chip on the right is a flash memory chip, which holds the circuit design for the FPGA.  If you’re not familiar with FPGAs, they are essentially a blank canvas for creating eletronic circuits using logic gates.  They have millions of gates or connections that can be configured into just about any digital circuit imaginable.




I’m very curious about the squigly lines shown above.  These traces, they were intentionally designed that way, I wonder why?

The chip on the bottom left of the below picture is the NTSC/PAL video encoder/decoder.


Another big chip!  This one is a Sunplus DVD/Mpeg1/2 decoder.  I suppose this is for playing movies off the SD card:


You can store Karaoke Movies on an SD Card and play them on the MagicSing.  There is special software called MagicSing Encoder that you need to use to get the best results.  There are lots of sources for Mp3/CDG files that can be converted to the video format usable on the MagicSing.  You can scrounge up CDG discs at yard sales etc and rip them to your hard drive if you have the right CD reader.


Here is the song chip.  This chip holds 200 songs.

The card edge connector is a 40 pin, 2 position, male variety.

The contacts are about 0.050″ (1.27mm) pitch.  Hard to measure!  The card is .031″ thick.

The actual chip inside is a NOR Flash variety.  Some information about NOR vs NAND memory chips:

The connector looks like a Harting 40 pin Motherboard to Daughterboard:

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This is a Spansion S29Gl064N90TF104 64 megabit NOR flash chip, storage space is 8 megabytes.  It is a 48-pin TSOP.  22 Address pins, 15 data pins. It can operate in 8 bit or 16 bit address/data communications.


This is a 40 pin edge card connector.  I’ve got a temptation to hook this up to my mbed enabled STMicro nucleo board and download the data to see whats in it!  The nucleo board is an ARM powered development board that costs $10 and has plenty of IO pins to connect to this chip.  I had thought seriously about trying to decode whats on this chip but in the end it will be fruitless.

Some work has been done by some smart fellas on NAND flash chip bit banging through the FTDI break out board.  I wonder how this could be adapted to the NOR chip?

Now for some screen shots.















Getting better prints – The ultimate first layer

There are a lot of variables involved in 3D printing.  Assuming you have the printer setup correctly and there are no loose parts to worry about, getting great prints depends on many different configuration parameters.

The most common workflow for 3D Printing involves these basic steps:

  • Design and export, or download, an .STL file
  • Load the .STL file in a slicing software (Cura, Repetier Host, Slic3r, Prontrface, etc)
  • Configure your desired quality settings (layer height, shells, infill, etc)
  • Print

However, let’s say for discussion, you’re not getting ideal results..

Getting an optimal first layer is important to your print because it is the foundation.  If it doesn’t stick properly to the bed, you’re print is going to come out awful.

The settings involved can be very confusing.  I’ll go over some very basic settings.

Layer height

This is the overall “print quality” and determines how smooth the walls of your print will appear.  The typical settings range from .1mm to .3mm and higher for really rough draft type stuff.


This determines the amount of “stuffing” your printed part will get.  A general rule is more than 33% is a waste.  Very strong parts can be made with 33% infill.  For basic things like Yoda heads or non-structural parts, you can get away with 15% or even less.

Shells or Perimeters


In the above image, I’ve drawn three red lines that line up with what are called the “shells” or perimeters of the print.  This setting in Cura/Repetier Host specifies this in mm value.  You divide this by the nozzle diameter (mine is .4mm) and you get the number of shells.  This basically is the “wall thickness” of your print.  You normally will not want this less than 3 times your nozzle diameter.


Top/Bottom Thickness

This is related to your layer height, and determines the number of top and bottom solid layers.  I have mine set to 3 (3x .4mm = 1.2mm)

For most printing, you’ll want solid top and bottoms.  For Vase printing, depending on your STL file, you might want to uncheck Solid Top to have a hollow top.  Also for Vase printing, you’ll want zero infill.  Then you just set your shells to your desired wall thickness.



3D Printing Fusible Alloys

I’ve been doing some research on fusible alloys. These are metals that have a very low melting point, around the temperature of boiling water (212 degrees F, maybe 95-100 degrees Celcius).

Care must be taken with many of these alloys because of most of them contain toxic ingredients such as Lead, Mercury and Cadmium.

The mixture I see working that is non-toxic is Bismuth and Tin.

So the steps roughly seem to include the following:

  1. Build an extruder
  2. Buy some Bismuth shot and Tin inguts
  3. Melt them together 62.5% Bismuth, 37.5% Tin
  4. Extrude to 3mm filament
  5. Print metal objects at about 95 degrees celcius

With a dual extruder setup, we could use High Impact Poly Styrene as a support material and dissolve it using Limonene.




Buy Bismuth from




Buy Tin from


Who’s with me!? In case anyone does this, you read it here first ! lol or maybe second…

Analysis of the Y Axis (Bed) on a Cartesian style printer

I’ve been observing the dynamics of the print bed on my 3D printer which is a Prusa i3 style Cartesian printer.  The bed has 3 linear bearings that rid along two smooth rods.  The bearings are arranged in a triangular pattern, with the drive belt down the center line.  I have noticed that with some bearings, that have play or are loose, I get wiggle in the bed.  I believe it is due to the following:


I’ve surmised that because the bearings have play, the motor applies a force on the bed which the single bearing receives as force across the horizontal axis in this picture, which is opposite (accros) the belt. This allows a “wobble” or slight rotation of the bed in the center point of the triangle.  Because of the unreliable specs of the bearings, each has a different tolerance and even the smooth bars may not be manufactured to any type of specification.  If the bearings aren’t fitting on the bar with minimal play, then you will get inconsistent layers, and your walls will not be smooth/straight.

For beds arranged like this, the situation is different and maybe non-existent:


Three bearing designs are great for machines that have expensive, tight tolerance components.  For RepRap printers, four bearings are probably better over all.

The following approach would minimize the problem for three bearing designs:


The reason for this is that in three bearing designs, you typically have “leaders” and “followers”.  The Leaders are the drive bearings.  The follower is a supporting bearing.

These are my theories based only few hours of observation and non-scientific brain-storming.  I’m not an engineer, just a mechanically inquisitive person who was raised in a junk yard.

3D Printing Bed Adhesion challenges

The difficulty with printing plastics using an FDM 3D printer is getting them to stick to the bed for the entire duration of the print.  There a lot of different common wisdoms that you will read about on the internet, and here is one more!

I’ve used ABS Juice for ABS, Blue tape for PLA, Glue stick, etc.  But Now I’ve found the ONE SIZE FITS ALL sticky stuff!  It’s Elmers Carpenter’s Wood Glue!

I diluted it in a mason jar, I didn’t really measure it, so you can just wing it.  Make it runny is all I can say.  Then apply it with a sponge brush.  Now all of my different filament materials including Nylon, PLA, ABS and HIPS stick to the bed!  They grip the glue very well, and I have no warping!  Check the pics!


In fact, it stuck so well, it pulled the lettering off the blue painter’s tape 🙂

The line you see in the plastic is where the two parts of painter’s tape joined together on the bed.


3D Printer build – it’s a lot harder than you think…

Anyone thinking about building a 3D printer from scratch should come to their senses quickly and just buy a ready-built printer or a high-quality kit. The prices are falling like a heavy rain and you can get a high quality printer for the same money, and less frustration, than building one will accomplish.

The problem is in the general design of the current crop of “open source” 3D printers.  There are just too many nuts, bolts, wires, haphazard software settings, firmware settings, mix-matched hardware and electronics issues to make it a user friendly experience.

First off, the motors.  Most people wanting to build a printer will rush to Ebay and buy the cheapest lot of 5 NEMA 17 sized motors.  These are the same people who don’t even know what NEMA 17 means.  Here’s a hint:  It is a form factor, not an electrical specification.  This means that NEMA 17 specifies the physical form of the motor’s case.  It does not dictate anything about the electrical current requirements, stepping angle, steps per revolution, etc.  All of these are “parameters” that affect the overall system, and they must be “plugged into” the software that runs on the controller board (aka firmware).


The same situation applies to heating elements, hot ends (the part the hot plastic comes out), temperature sensors, fans, end-stops (the little switches that tell the controller that your motor has moved the carriage into the 0 position).

Each and everyone of these are elements that must be hard coded into the device firmware.  There is no user-friendly machine-mounted menu option for these parameters.  In fact, depending on your other choices, you might not get an LCD screen at all (which is where the machine-mounted menu system is displayed).

I’m building this printer as a means to and end.  I need to experience it the “hard way” sothat I can design the “easy way”..

Here are some of my observations so far:

  • Nuts, Bolts, Screws – there are too many.
  • Settings buried in firmware – they should be easily accessible via software.
  • Wires – need to manage the vast pile of wires.  This means better end to end connectivity.  Perhaps using 4, 6 and 8 wire RJ-45 style connectors would make this a lot nicer to build.
  • There should be a “setup wizard” software that guides you through configuring the firmware for the first time. It should auto-detect that the printer has not been configured and guide the user through the process.  This could be a desktop application or available in the printer’s LCD controller (but not all have LCDs…)



RepRap 3D printer project is not for the faint at heart

So I launched my “RepRap” 3D printer project a few weeks ago.  I am building the Prusa i3 printer using 6mm acryllic for the front and side support wings.  A picture of it is shown below:


Although I decided to scribe my nickname “Thetazzbot” in the printer’s frame, it should not be confused with “Taz” by lulzbot.  I’ve been using “thetazzzbot” since the 1990’s, and I’m not going to stop using the name now just because some company decides to use “Taz” as their product name.  Maybe I should trademark my name…

There are numerous “RepRap” printer designs available for the do it yourselfer.  The concept is theoretically good:  Build a bare bones printer, then use it to build the parts for a better printer.

The original design, aka Prusa Mendel, was built using threaded rods, a lot of washers and nuts, and even though I’ve never built this specific printer, I can tell you it will be a pain to build.  The critical part of the printer’s construction is alignment.  And all those threaded rods will be difficult to get the intersections aligned where the angles aligned and the whole thing squared up.

The other downside of the current generation of RepRap printers is the number of unique parts involved.  This includes threaded rods, screws, nuts, bolts and printed parts.  If you look at the bill of materials, it is quite staggering.  To picture it even better, take a look at this photo:


Let me reiterate, there are a LOT of parts that go into building your own RepRap Prusa Mendal or i3 printer.

Depending on the model you decide to build, you could also be facing “printed parts fatigue”:


Or, Nuts-And-Bolts-Hell:


There are even MORE if you decide to build a Makerbot or Ultimaker clone.

I also have a great deal of heartburn with the “wires hanging everywhere” approach that the DIY community seems to be in love with.  This haphazard appearance makes the machine seem unapproachable by non-techies.  Exactly the opposite of what we need for mass adoption of the technology.


The DIY community needs to try to reverse this trend.  I vote for Less is More.  Not every printer needs to have an 8″x8″x8″ build volume.  What if we started building task-specific printers that didn’t need the height (simplifying the Z axis), or a heated build platform (negating the need for big beefy power supply), or maybe use smaller, cheaper stepper motors, DC motors.

My goal is to build a platform that doesn’t require screws, or tools.  It shall have a wide platform (12×12 inch or 12×14 inch), with lower vertical build space requirements for printing small, flat parts.  The goal of this project is to reduce parts count drastically, and reduce construction complexity such that anyone can assemble it.

My bare minimum design includes:

  • Single board controller + stepper drivers
  • Hotend for PLA, Nylon, etc.  Experimentation here..
  • X/Y Nema17 or smaller steppers
  • Z with 4″ or less of travel
  • Little or no bolts/nuts/hardware (expensive)
  • Utilize inexpensive aluminum square tubing
  • Stationary build platform
  • Bowden style extruder

I’ve just finished designing and printing the plastic parts and cut the frame and test fitted everything.  So far very good results.  Now I have to put together the wiring and controller and then run some motion tests.

The long term goal of the project is to build a low profile, highly stable platform that is inexpensive to reproduce and simple for the end user to assemble and get printing.

Using a permanent marker to make circut boards

I’ve been considering the best approach to making my circut boards with the Cricut Expression (aka FreeExpression).

The board design software I use is called Eagle Cad.  It is free for small designs and can generate HPGL files that I can send to the Expression via my custom firmware.

First off, I’ll need a suitable pen that will produce ink which can survive the etching bath.  The go-to marker for this purpose is the Sharpie ultra fine permanent marker.


However, in my past experience with this marker, the results were less than desirable.  The copper under the ink will be pitted and can result in open connections on fine traces.

I’ve had much better luck with the Staedtler Lumocolor Fine Point Permanent Marker


These pens are pretty expensive too..

If you can’t find them at your Office Depot or Staples in the Pen/Markers section, look in the Drafting Supplies section.  That’s where I found mine.

Do not buy the Staedtler Fine Pigment Ink Archival pens.  They do not work at all.  (See below).

I bought two sets of pens.  The Staedtler Lumocor set of colored pens, and a set of four Staedtler Pigment Ink Archival pens.  As  a writing instrument, these archival pens are incredible.  They write so fine, and the ink is acid free, waterproof, won’t smear or smudge.  It’s awesome.  As a PCB writing tool, forget it.

I grabbed a scrap board and used each pen to write the color name.  Then I used each of the archival pens to write the point size.



Then I headed to the Ferric Chloride bath.

If you don’t want to use Ferric Chloride, read this article for a home made alternative.

After 45 minutes, had my results.

First observation: 45 minutes was too long 🙂  Probably somewhere between 30 and 45 minutes.

Second observation:


So, ranking the colored pens in order of preference:

  1. Black
  2. Green
  3. Orange
  4. Brown

The rest were unusable IMHO.  Red used to work a few years ago.  Seems they changed the formulation.  I’m going to repeat this test using Acid/Peroxide mixture.  Another alternative is Sodium Persulfate.  I have some Ammonium Persulfate on hand, but it is hard to get the mixture right.  Problem with both persulfates is that the mixture loses it’s strength over time, so letting it sit on a shelf for a couple of weeks it will be useless.  Not as long lived as Ferric Chloride.  The Acid/Peroxide mixture etches much faster though.

Be sure if you use acid/peroxide, do it out doors.  My workshop is poorly ventilated so I can’t use that stuff indoors.

To be continued…

Low cost markers that fit the Expression

I found some inexpensive markers that fit (a bit tightly) the pen holder in the Cricut Expression.

They are $2.97 at Walmart, and can be found in the kid’s coloring section with the crayons.  They are Cra-Z-Art Washable Mini Markers.  I didn’t notice the “Washable” bit until just now as I was writing this post.  The mini Sharpies might work too, but they are a bit expensive.  I’ll probably browse the shelves at Office Depot to see if I can find the Sharpie minis.