Case for a FM-radio (Velleman MK194)

Making good use of a 3d printer

I have a MK194 radio kit from Velleman and turned it into a radio some  time ago. The radio looks pretty cool with all the electronic components visible but the wooden case was awful. I therefore decided to build a new case for it. Of course I want to use my Hephestos 2 printer from BQ to make this case.

First I designed a case in FreeCAD. I use FreeCAD for a couple of weeks now, together with OpenScad, but this is the first design with multiple parts that I create with it. After several iterations I finally decided to have a design consisting of three parts. A box, a support plate for the radio PCB and a lid. The radio fits into the support and the lid which are then screwed onto the box.

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Design for the radio case made with FreeCAD consisting of three parts (the red part just represents the MK194 PCB). I made a nice radius on the lid and the MK194 fits nicely between the support and the lid.

Continue reading “Case for a FM-radio (Velleman MK194)”

Blogger vs WordPress

Should I move my blog from Blogger to WordPress.

My sister asked me to create a website for her business. In all honesty, it’s been some time since I last made a website so I did some research before I started. I quickly found out that WordPress is now the dominating platform or content management system (CMS) as it is called. It’s also completely open source (GPL license) which is a big bonus for me. It therefore didn’t took me long to decide to use WordPress for the website.

While working with WordPress I was impressed by it’s the ease of use and the huge number of themes. Also the support on the internet is excellent. So I began asking myself if I should move my blog from Blogger to WordPress. Continue reading “Blogger vs WordPress”

What to make for Valentine’s day?

Looking for an idea for Valentine’s day. Look no further.

What to make for Valentine’s day? A bare perfboard with a Valentine’s chaser (basically a 555-chip, 4017 decade counter and a handful of leds) doesn’t look too impressive. That’s why I made this heart shaped wooden box with a laser cutter. Both printboard and battery fit nicely into the box. Three bolts, nuts and washers to finish the job.

The file for the laser cutter (.svg) can be found here.

And here is a 3d printer file (.stl) of a little dock for the heart.

 

Assembling a Hephestos 2 printer

Is this 3d printer a good choice for a beginner?

Introduction

While making my projects like the Darth Vader chest box 2.0 I use the local fablab a lot, especially the laser cutter and the 3D printer. It was a bit boring to wait for the 3D print to finish (laser cutting is typically much faster) with not much else to do at the fablab. I therefore decided to buy my own 3D printer. I choose for the BQ Hephestos 2, a sturdy Prusa i3 all metal printer that comes in a kit. Continue reading “Assembling a Hephestos 2 printer”

Darth Vader chest box finished

Most impressive. Obi Wan has taught you well.

The main features of the Darth Vader chest box are:

  • enclosure laser cut plywood (6mm)
  • easy control with four push buttons
  • DIY voice changer circuit with Holtek HT8950A
  • LM386 amplifier
  • build-in speaker
  • audio-in (3.5mm)

When I started the Darth Vader chest box early december 2015 I didn’t expect it would take me almost two months. Finally this week I finished it and I’m happy to say that it works great. For a couple of weeks it was almost finished but there always seemed to be some work to be done. A major problem was that I couldn’t get the 3D printed container for the audio-jack right. I tried it several times at my local fablab but it just didn’t fit. Finally I ordered the container from 3D Hubs and it had a perfect fit. Continue reading “Darth Vader chest box finished”

Expanding my electronics workbench with shelves

You can never have enough space

Last week I made a electronics workbench from scaffolding wood and galvanised steel. When working with electronics you need a lot of storage space. Therefore I wanted to make shelves, preferably in the same style as the workbench. I like the workbench but the price of the galvanised clamps was steep. Luckily I found an online supplier that offers the clamps for 1/3! of the price that I paid at my local hardware store. The total price of the shelves was $30 using some scaffolding wood that was left over from the bench.

I sanded the wood thoroughly carefully removing all splinters, drilled two 28mm holes for the steel pipes in each shelf. Next I applied three successive layers of oil to the wood. I cut the steel to the desired length and assembled the clamps. Each shelf is hold in place with 28mm lock rings. I fastened the whole construction to the concrete wall. Below is some imagery of the shelves and the workbench.

The now populated electronic workbench and much needed shelves.
Finished scaffolding wood, galvanised pipes, clamps and locker rings. Time to assemble the shelves.
Top shelf with the clamp and lock ring visible.
Detail of the bottom shelf. With the socket screws it’s very easy to adjust the construction.
Finished shelves fastened to the wall.

 

Homemade desk of scaffolding wood

Introduction

The desk that I used as an electronics workbench is rather small. Since my electronics hobby is expanding, as hobbies tend to do, the small size of the desk became a burden. It was time for a new one. While searching on the internet I found an L-shape desk from reclaimed scaffolding wood on Etsy. The L-shape desk will fit perfectly into the corner saving a lot of room. The desk is really nice but is also very expensive (about $1500). Looking at the image I thought it is not very difficult to make even with simple tools. I was able to build it for $300 with eight planks of scaffolding wood (8″ wide), three planks 2.5″ wide , 6 galvanised pipes one meter length (28mm thick), four T-clamps and four supports clamps. Here are some photo’s of the table and the building process.

Note: I later discovered that the clamps and pipes can be bought online for onethird! of the price that I paid at the hardware store cutting the material cost by half ($150).

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Scaffolding wood sawn and sanded.
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Cutting the pipes with a Dremel DSM-20.
Assembly with a 2" board screw
Assembly with a 2″ board screw
Using a an oil instead of a varnish. Applied with a towel to in three layers to darken and protect the wood.
Using a an oil instead of a varnish. Applied with a towel to in three layers to darken and protect the wood.
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L-shaped table placed in a corner of the room. I added some support to flatten the top of the table. I also flushed the screws with the surface.
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Installing my tools and parts on the table and below.

The Darth Vader chest box is almost finished

Introduction

The last month I’ve been working on my Darth Vader chest box. I’ve designed and built my own circuit with the Holtek HT8950A voice modulator, I create a laser cut case and designed 3D printed parts for the chest box. Since I had to learn a lot of new techniques, e.g laser cutting and 3D printing, this is by no means an easy project for me. With the project in it’s final stages now some design problems turn up that need fixing.

Soldering the board.

This week I soldered the components to the board. First I soldered the voice changer components and made sure this part of the circuit is working. Next I soldered the amplifier. I tested the total circuit and it worked the first time which is always a joyful moment. I find the Adafruit perma-protoboard very easy to work with since I’m able to copy the layout from the breadboard. Next I grouped all the buttons that operate the HT8950A on a board and soldered them to a piece perfboard. The buttons on the perfboard fit nicely into the laser cut side panel that I already made. Operating the chest box is easy with this (a major issue with my previous chest box).

Soldered perma-protoboard and breadboard side-by-side.
Close-up of the soldered board with the HT8950A voice changer chip on the right and the LM386 amplifier on the left.
Operating the voice changer with this panel should be easy.

Design issues

Last week I made 3D printed parts for the front of the chest box. Unfortunately I found that these parts didn’t look good with the laser cut box. The plastic parts just didn’t do justice to the laser cut plywood. I therefore decided to laser cut all the parts that sit on the from of the box with I think is aesthetically more pleasing.

Another problem arose with the female audio jack connector that I need to plug in the microphone. The thread of this 3.5mm connector just isn’t long enough to be fitted onto the 6mm thick plywood. I designed a container to solve this. The audio connector fits into this container and the container is screwed to the case. Hopefully this container solves the problem.

Container for the audio jack connector created with Openscad. The container, screwed to the chest box, will keep the audio connector tightly to it’s place.

Yet unsolved problems

  • I need to attach a nylon belt to the chest box. I’m thinking about popper snap fasteners attached to the belt to open or close the belt.
  • The HT8950A works fine with a proper audio signal as input but the microphone that I have, a small electret microphone, doesn’t give any audible output (except for noise). I assume that the signal is to weak and therefore needs amplification.

Designing parts for the Darth Vader chest box with OpenScad

Introduction

A new year, a new beginning. Last year I took a fair interest in technologies like laser cutting and 3D printing but I still relied on my old 20th century skills for my projects. I must admit that the investment in time to master these new technologies was holding me back to advance in both laser cutting and 3D printing. In the very last month of 2015 I took the decision to produce a case with a laser cutter. It was a revelation. A job that would normally take me a day or so was done in a matter of minutes with a precision that I can never achieve with the old saw and chisel. From that point on I decided to invest heavily, in both time and money, in these new technologies.

OpenScad

First I learned to work with Inkscape, a free 2D vector drawing program for laser cutting. I discovered that it is a good tool for illustration (e.g for web design) too. Next I needed a 3D design tool to create parts with a 3D printer. I looked at different programs such as Sketchup, 123D Design but I increasing dislike the proprietary character of these programs. Echoing the words of Richard Stallmann “the proprietary program is a system of unjust power”. On the non-proprietary side there is FreeCAD and Blender but I found the learning curve of these programs too steep. Then I discovered OpenScad when reading an article on HackaDay. It’s a free (as in free beer and free speech) program running on Windows, Linux and OSX that has a great community. Instead of using a GUI the user has to scripts his models with a simple descriptive programming language. This seems strange and cumbersome at first but it actually works for me. I found it very easy to get into. OpenScad is very lightweight. A GUI in CAD programs tends to be a burden on a PC and OpenScad lacks that GUI. Because of the script that OpenScad uses it is very apparent what is in the 3D model and what the dimensions are. Lastly the script is saved with the model. The comparison with HTML comes to mind. Therefore it is possible for anyone else to see how a model is made, learn from it and make changes to it. For now OpenScad works for me although I’m not sure what will happen if I’ll try to design more complex 3D models.

Combined elements of the front of the Darth Vader chest box made in OpenScad. Still needs some work.

Parts for the voice changer

The Darth Vader chest box has a very distinctive look with lots of distinctive buttons and other parts (see images below). I modeled these parts with OpenScad beginning with the simple buttons working my way up via the coin slots to the complex rods. I’m satisfied with the result thus far. Next I’ll 3D print the parts and glue them to the plywood chest box I made earlier.

Probably the most simple parts of the chest box are the buttons at the bottom of the box. Modelled in OpenScad.
Coin slot type of parts for the Darth Vader chest box. 
Rods for the Darth Vader chest box.

Homemade Darth Vader Voice Changer 2.0 (work in progress)

Introduction

The last couple of weeks I worked on a homemade voice modulator that is easy and cheap to built. First I’d like to mimic the Darth Vader Voice Changer, but with the press of a button it can be changed to robot or helium kind of voice effects. Last week I’ve steadily continued my work. The project has two main parts, the electronics and the case.

Electronic circuit

For the project I choose the HT8950A voice modulator from Holtek as the heart of the circuit. It is cheap, versatile and easy to work with. I previously had the voice modulator working. I only had to amplify the signal which seemed simple enough. Well, that turned out to be a bit more troublesome than expected. After connecting the LM386 to the circuit and powering it up an annoying hiss was introduced. After some experimenting I figured that the breadboard was to blame and decided to copy the circuit to another breadboard. Although on the new breadboard the hiss appeared somewhat reduced but it was still at an unacceptable level. Even when I removed the input signal from the LM386 the hiss continued. I connected the HT8950A with a audio-jack to an external amp. I wanted to make sure that the hiss was coming from the LM386. With the external amp the hiss was gone. The fact that I had hiss without an input signal indicated that the supplied voltage wasn’t clean.  To clean it up I placed a small capacitor (10nF) from pin 6 (V+) to ground and voila the hiss was gone (see schematics below). It took me some time but I’m almost ready to finish this circuit and solder it to perfboard.

Two (almost identical circuits) with the Holtek HT8950A voice modulator and the LM386 amplifier. Both circuits gave a hiss which was unacceptable. Eventually a simple 10uF capacitor from pin 6 to ground did the trick for me. 
Schematics of the Darth Vader voice changer. I was able to eliminate all the hiss and noise from the LM386.

Printing the case.

I decided previously to make a T-slot plywood case for the Voice Changer but I’m not satisfied with the result. First I made a beginners mistake with the tab width. It was chosen poorly resulting in fragile edges of the case. Also I discovered that a T-slot case is not the best choice for this project. The case needs to be sturdy and the T-slot isn’t. I’m afraid it will fall apart when in use. Therefore I’ll made a regular finger joint that will be glued together. This new case was much better. Gone are the fragile edges and I’m confident that glued together it will be very sturdy.

Laser cut case made out of plywood. I first used a T-slot type of case but made a beginners mistake with the tab width and positioning. As a consequence the edges become very fragile. The front of the case has engravings for the positioning of large controls of the voice changer. These controls on the front will we dummies just to mimic the look of a Darth Vader voice changer. The actual controls will be on the side of the box.
Laser cut case with regular finger joint. This attempt is much better.