Experiment 17: Set Tour Tone revisited

While working on the Atari Punk Console I reread the part of chaining chips in Experiment 17 of Make:Electronics (pg167). I then realised that I didn’t do all the experiments that are described in the book. Since Experiment 17 contains a lot of information and chaining 555 chips is common practice in electronics I decided to at least one of the remaining experiments. This experiment is described in figure 4-30 (pg169). In this experiment the output of the first 555 chip is connected to the control (pin 5) of the second 555 chip. Both timers are in astable mode. The second chip drives a speaker. The first 555 chip, that oscillates slowly, slowly decreasing the pitch of the of the sound generated by the second chip until the cycle of the first chip ends and the frequency drops. This results in a slow whoop like the sound of a siren.

After building the circuit the sound produced was very distorted and unlike the slow whoop I was expecting. The LED connected to the first chip performed as expected with about one pulse per second. After inspection of the circuit I noticed that the 100 ohms resistor in series with the speaker had become very hot. I changed it for a resistor of 180 ohms and now the circuit worked fine. I substituted a 10K potentiometer (see images below) for the R7 resistor (1K) which made some interesting changes in the slow whoop (higher or lower pitched).

At this point in the book I believe the use of an oscilloscope would become interesting even helpful.  I would be able to analyse the waveform on several pins of the circuit. The oscilloscope is however an expensive piece of equipment which I don’t own yet. It will put it on my wishlist. Something I noticed with this hobby that there appears to be an ever increasing need for space, equipment and components.

A video of the experiment, with several tweaks of the circuit, is available at https://www.youtube.com/watch?v=d_ADg2LS3fA

Complete circuit of figure 4-30. R7 is substituted with a 10K trimmer.

Close-up of the circuit.

Atari Punk Console part 2: the perf board

Yesterday I soldered the Atari Punk Console that I had built on a breadboard previously onto perf board. I used the Adafruit Perma-Proto (half-size) which is very convenient because of the breadboard lay-out of this perf. Then I made a classic mistake. Having little time I tried to solder the components onto the board as fast as possible. This is a simple circuit so I thought I could afford myself to do this. No wonder I connected some of the components wrongly. I had to desolder them and had to redo a lot of my work (see the close-up in the image below). The lesson here is; never try to rush while working with an iron (for more than one reason). Anyway I completed the job and the circuit appears to be working fine. In the next step I will build it into an enclosure.

Overview of the circuit with the two potentiometers below
Close-up of the breadboard with two 555 chips in the middle. 

Atari Punk Console part 1: the breadboard

Before entering experiment 19 of Make: Electronics and the ‘realm of pure digital electronics’ I decided to do an analog project first. I want to make a Stepped Tone Generator aka Atari Punk Console. This piece of electronic is a very basic synthesizer, probably the simplest that one can create. The circuit was first published in 1980 as Stepped Tone Generator and later renamed as Atari Punk Console. The name Atari Punk Console or  APC stems from the circuits ability to generate sound similar to the old Atari 2600 console. It is relatively easy to build and fun to play with.

There is even a dedicated website of the Atari Punk Console with shows a wide variety in both electronic circuits and enclosures (http://www.ataripunkconsole.com/).

The circuit is similar to some of the circuits in experiment 17 especially the ones shown in figure 4-28 and 4-30 of the book, two circuits I haven’t built yet. The Atari Punk Console consists of two 555 chips that are chained. The first 555 chip is in astable mode and drives a second 555 in monostable mode (compare this to figure 4-28 where a 555 chip in monostable mode drives a 555 in astable mode). Each chip has one potentiometer connected to the pin 7. These potentiometers function as the user interface of the simple synthesizer.

In this first step I have built the APC on a breadboard. I used the schematics and components shown below except for the potentiometers which are 500k in my case. The result is satisfying because your able to play with the console and generate some decent sounds with it.

Schematics of Atari Punk Console
Breadboard with APC circuit

Close-up of APC with two 555 chips in the middle.

Another close-up of the circuit

Experiment 18: Reaction timer part 5 (finished)

I (almost) finished the reaction timer today. That means that the delay is build in. This was done by adding yet another 555 timer now in monostable mode. It is triggered with a tactile switch connected to pin 2 of the timer (see pg. 178 of Make:Electronics). During testing of the circuit the LED switched on immediately which was not supposed to happen. After some investigation I discovered that the resistor connected to pin 7 of the last added 555 chip was 330 ohm instead of 330k allowing the capacitor (C5) to be charged far to quick. After solving the problem I exchanged the capacitor of the first 555 chip (C2 in astable mode) from 100uF to 0.1uF increasing the number of pulses per second a thousand fold. Finally I was able to test my reaction. In conclusion Experiment 18 is by far the most complex circuit that I plugged into a breadboard. Nevertheless due to the step-by-step of the book approach I was able to complete without too much trouble. Linking IC’s together is demonstrated very well with this experiment.

Further text at page 179 and 180 suggests how to calibrate the whole circuit without an oscilloscope. At this point I’m not sure if I want to do this because I don’t want to take this project any further by enhancing it or even create a project box.

The video of the different stages of experiment 18 can be found on https://www.youtube.com/watch?v=B5Pbp3wZJUg.

Overview of the finished circuit.

Close-up of the three 555 chips in the middle with on the left the 555 timer that provides the delay.

Experiment 18: Reaction timer part 4

Previously I added 555 timer in astable mode to generate pulses for the counter chips. In the next step a second 555 chip is added. This timer runs in bistable mode (see pg. 176 of Make:Electronics). The purpose of this timer is to freeze the counting when the tactile switch is pressed (figure 4-40 of the book). The output (pin 3) of the timer is connected to pin 2 (disable pin) of the first 4026 decade counter. Adding this timer to the breadboard is straightforward. The only problem that I face is that the breadboard is becoming very crowded. The good news is that the circuit is almost finished. In the next step I will only have to add one more 555 chip.

Overview of the circuit which is becoming very crowded. 

Detail of the circuit with the two added 555 chips in the middle and the tactile switches left.

Video of experiments directly to YouTube

Today I decided to upload my movies of the Make: Electronics experiments directly to my YouTube channel at https://www.youtube.com/channel/UCPwwPIXHMZYcVyJ2SuRJjuA/videos . The reason is that the video that I included on blogger.com are of very low quality. I also decided to make one video for an entire experiment. This gives (hopefully) a better overview off the several steps during a experiment.

Experiment 18: Reaction timer part 3

The next step in Experiment 18 of Make:Electronics is the addition of a 555 timer in astable mode to the circuit (pg. 175 of the book). This addition drives the decade counter therefore the tactile switch that was connected to pin 1 of the first decade counter from the previous part of the experiment had to be removed. At first I had the two capacitor exchanged so instead of four pulses per second the display counted frantically. After solving this I encountered no further problem. For the larger capacitor connected to pin 6 of the 555 chip I used 100uF instead of the 68uF so my circuit is probably down to three pulses per second.

Circuit with the 555 timer included however the two capacitors (above the 555 timer) were exchanged.

Circuit with the capacitors in the right place.

Experiment 18: Reaction timer part 2

Last Friday I built the circuit as displayed in figure 4-37 (pg. 174) of the book Make:Electronics. The circuit consists of (in my case) three Kingbright 7 segmented digits. Each digit was connected to a 4026 decade counter. The decade counters are coupled by connecting the output of pin 5 (carry) to the clock input (pin 1) of the next counter. These are the blue jumper wires in the middle of the images below. As you can see a lot of jumper wires were needed. Every pin of the decade counters needs to be connected either to the digits or to the positive or negative voltage.
When I applied voltage to the circuit for the first time a problem occurred. The display immediately showed random numbers although I did not touch the tactile switches. A closer examination of the circuit showed me the cause of this problem. The pull-down resistor of the push button clock input of the first counter was not properly connected. This problem was easily fixed and the circuit worked then flawlessly however with one mistake. I had connected the first decade counter to the leftmost digit instead of the rightmost.
Although this experiment is a bit tedious with all the connections it was worth the trouble once I saw that the display worked properly and I was able to count to 999.     
Overview of the circuit corrsponding to figure 4-37 of the book.  
Topdown image of the circuit where the  tactile switch to the left is connected to pin 1 (clock input)
and the switch to the right is connected to pin 2 (disable clock) of the first counter.

Experiment 18: Reaction timer part 1

With the arrival of the Kingbright numeric LED with the correct width (see my earlier post) I was able to continue experiment 18 of the book Make:Electronics (pg. 170). In this experiment the reader will eventually build a reaction timer using the 555 timer chip and 4026 decade counter. The layout of my numeric LED is a little different than the one from the book so I have to change the connections to the 4026 decade counter later in the experiment accordingly.

In the first part of this experiment you simply test display. This is done by sticking the three numeric LED’s in the breadboard and applying voltage to the succesive pins. Before applying the voltage I connected pin three of every LED to the negative site with a resistor in between. Then I connected positive voltage to all the other pins (see image below).

Next I connected a 4026 chip to one numeric LED. Connecting is easy. The only problem is that I needed a lot of connections already while later in this experiment all three LED will be connected. Pressing the tactile switch sometimes prompted the display to skip a number. This effect is described as switch bounce and described on pg. 174 of the book. Apart from that the whole experiment went pretty smooth (see the video below). To be continued.

Applying positive voltage to a pin of the first numeric LED.

Numeric LED connected to the 4026 decade counter.

DIY cushion for bar stool

This week my wife completed a couple of cushions for our DIY bar stools made of scaffolding wood . At the local market she bought fabric and foam. The fabric is of firm upholstery quality in an apple green color. This matches the color of the wood. The foam was already cut at the right size. To make the cushions the fabric for one cushion was cut into two even halfs.  These halfs were sewed together along three sides creating a sleeve. One side was held open to tuck in the foam. The open side of the fabric was then stiched by hand. Now I can sit on the stool for a prolonged amount of time without blocking the bloodcirculation to my legs.

Bar table and stools with cushion.

Fabric and foam.

Foam tucked in.
Detailed view of the bat stool and the cushion.