10 Step Analog Sequencer

Hello everybody! I'm back with another tutorial. It's been quite a bit of time since I posted my last tutorial. So, this one's basically about how to build a 10 Step Analog Sequencer. You may also call it an Atari Punk Sequencer. Here are some of its features:

• It has a built-in Tone Generator (Atari Punk Console).

• It has an input audio jack which helps it to step the sound of any external audio source up-to 10 steps.

• It has a pitch control for each of the individual steps. They work excellently when using the inbuilt tone generator. When using any external audio source, they help it in varying its dynamic thing and feel.

• It has a potentiometer for controlling its tempo.

• It also has another potentiometer for volume control.

• It has a number of switches for turning on each individual step.

• It has a potentiometer for selecting its mode. This sequencer operates on two modes (I could have used a SPDT switch for that). Now, for that in Mode 1, it only steps up to the number of steps on before the next step is on and, after that, returns back to the first one. In Mode 2, it steps up to the number of steps switched on and, after that, switches the steps which are off and then continues the ones which are on.

• It has an internal built-in speaker but can also be used with an external speaker which can be selected with the help of a switch.

Before getting started with this project, I would strongly recommend you to try to make the Atari Punk Console and the LED Chaser; since this is a combination of them both and much more. You must also be familiar with reading schematics.

I have given a lot of informative stuff in this tutorial about different ICs used in this project, the power supply, etc., and have also embedded some videos that I found really informative and worth watching. These are not made by me and I don't own these videos about the ICs and other stuff. I've linked up the profile pages of the respective uploaders in the steps.

Do check out the above videos of the sequencer uploaded by me. They give a view of this awesome sequencer that's worth building.

I do hope that people don't just take my schematic and make everything on the perfboard and just finish up with the project. I want everybody to actually learn something while making this project.

There are lots of versions of this Sequencer; I'd recommend you to check them out too before starting up with this because you'll get lots of other ideas, too.

I think that Wikipedia might explain it better than me:

"An analog sequencer is a music sequencer constructed from analog electronics, invented in the first half of the 20th century. At its most basic, an analog sequencer consists of a bank of potentiometers and a 'clock' (pulse generator) connected to a sequencer, which steps through these potentiometers one at a time and then cycles back to the beginning. The output of the sequencer is fed to a synthesizer. By 'tuning' the potentiometers, a short repetitive rhythmic motif or riff can be set up."

Step 1: Gathering the Parts

Parts required for the 10 Step Analog Sequencer:

• Electronics Enclosure (I used a cardboard box and decorated it with handmade paper)

• Perfboard

Potentiometer

• 470K x3

• 22K

• 100K x11

Integrated Circuits (ICs)

• CD4017N

• NE555

• 556

• LM386N

IC Base

• 8 Pin x2

• 14 Pin

• 16 Pin

Capacitors

• 1000uF

• 4.7uF

• 0.01uF x3

• 0.1uF

• 10uF x3

• 0.047uF

• 1uF

Diodes

• 1N4148 x20

LEDs (any color) x10

Resistors (all ¼ watt)

• 1K x3

• 470

• 10K x2

• 4K7

• 10 Ohms

• 47K

Switches

• SPDT x11

• SPST

• DPDT

Speaker: 8 Ohms

• Transistor - BC547 (Any Similar type like BC548, 2N2222 should work)

Audio Jack

• 3.5mm Audio Jack Female x2

• ¼ inch Audio Jack Female x2

Parts required for building the Power Supply:

• Transformer - 12-0-12 500mA Centre Tapped

• AC Connector/CPU Socket (IEC) 220v

• IC 7809CV

• Heatsink

• Diodes - 1N4007 x2

• LEDs (any color) x2

Capacitors

• 470uF X 2

• 1000uF

Resistors (all ¼ watt)

• 2K2

• 1K

All these are the minimum parts required for building the 10 Step Analog Sequencer. If you wish to, you may remove the power supply and use a battery as the power source.

Apart from this, you may use a number of other parts like:

• Male and female connectors for connecting all off board components like potentiometers, switches, etc.

• Nuts and bolts to fix the transformer, AC connector, etc.

• LED Holders for mounting the LEDs.

Besides you might also require the following parts in building the sequencer:

• Solder Iron

• Solder Wire

• Perfboard

• Multi-meter

• Heat Shrink/Electric Insulation Tape

• Glue Gun

• Wire

• Third hand Soldering Helping Tool

Step 2: The Schematic

This sequencer has a really big schematic which has been edited by me. I've basically combined the schematics available at the following links:

• http://taintpaul.com/?cat=16&order=asc

• http://www.midiwall.com/gear/babyseq/

I hope that you do try experimenting with the circuit yourself on a breadboard or something. People shouldn't just build the schematic on the perfboard and assemble everything and then it's just done. I basically want you to learn something as you do this project. I've given a lot of information about various things in the upcoming steps.

I recommend you try experimenting with different resistor and capacitor values with the 386 amplifier and the circuit around the transistor. You can also use a number of transistors with the outputs of the 4017 IC. You can indeed do a lot of creative stuff like trying to substitute the 555 timer in the astable mode by building an astable multi-vibrator using transistors. You can use various transistor amplifiers instead of the 386 IC. I tried a lot but ended up burning a lot of them. If you're interested in doing so, you can also make the 555 timer on you own. Visit the following link.

I just don't want people to you know basically do exactly what I did. I want to see people working with their own mindset and their own ideas. I basically want people to experiment and learn more. I hope that people really do so and please share your work with me. I'll be really happy to see your self-modified circuit diagram and sequencer. I believe that the world will be a better place to live if people are really motivated to put forward their own ideas and work hard towards them.

Please notify me if there are any corrections needed in the schematic.

Step 3: The Brief Overview

Well, the schematic at first might just look a bit too scary! There's nothing to worry about. I'll divide the schematic briefly into some sub-parts in order to make it easier to understand. The schematic consists of the following parts:

• The Power Supply (the transformer, 7809 IC, etc.)

• The 10 Step Sequencer (the 555 timer, CD4017 Decade Counter with 10 switches, potentiometers and LEDs, etc.)

• The Tone Generator or the Atari Punk Console (the 556 dual timer, etc.)

• The Transistor Circuit enabling the sequencer to step the sound of external Audio Sources.

• The 386 Audio Amplifier

We require the voltage regulator if you choose to use a power supply with a transformer and a rectifier. But if you simply use a 9V battery unlike me, then you don't need to use the voltage regulator.

I have attached the datasheets of all the ICs and the transistor in their respective steps.

Step 4: The 555 Timer

The 555 timer IC is an integrated circuit (chip) used in a variety of timer, pulse generation, and oscillator applications. The 555 can be used to provide time delays, as an oscillator, and as a flip-flop element. Derivatives provide up to four timing circuits in one package.

The IC 555 has three operating modes:

• Bistable mode or Schmitt trigger: the 555 can operate as a flip-flop, if the DIS pin is not connected and no capacitor is used. Uses include bounce-free latched switches.

• Monostable mode: in this mode, the 555 functions as a "one-shot" pulse generator. Applications include timers, missing pulse detection, bounce-free switches, touch switches, frequency divider, capacitance measurement, pulse-width modulation (PWM) and so on.

• Astable mode: The 555 can operate as an electronic oscillator. Uses include LED and lamp flashers, pulse generation, logic clocks, tone generation, security alarms, pulse position modulation and so on. The 555 can be used as a simple ADC, converting an analog value to a pulse length (e.g., selecting a thermistor as timing resistor allows the use of the 555 in a temperature sensor and the period of the output pulse is determined by the temperature). The use of a microprocessor-based circuit can then convert the pulse period to temperature, linearize it and even provide calibration means.

This project uses three 555 timers (or one 556 timer and one 555 timer); two in astable mode and one in monostable mode.

The Tone generator is an astable square wave oscillator driving a monostable oscillator that creates a single (square) pulse. There are two controls, one for the frequency of the oscillator and one to control the width of the pulse. The controls are usually potentiometers but the circuit can also be controlled by light, temperature, pressure, etc. by replacing a potentiometer with a suitable sensor (e.g., photo resistor for light sensitivity).

The Tone generator is built using the 556 dual timer which consists of 2 independent 555 timers.

References:

• https://en.wikipedia.org/wiki/555_timer_IC

The video embedded in this step is for educational purposes only. It is the property of its creator Rob Winter, uploaded on YouTube. Check out his page here.

Step 5: The 4017 Decade Counter

In order to understand the working of IC CD4017, one must know about its individual pins. It has 3 input pins, 10 output pins, one ground pin, one for the positive voltage supply and one for carry out pulses. Pin diagram of CD4017 is given in the pictures above.

Input pins

• Reset pin (pin 15) - It is used to reset the counter to zero. For instance, if you want the counter to count up to third output then connect the fourth output to pin 15. Now after every third output, it will automatically starts counting from zero.

• Clock pin (pin 14) - Whenever pin 14 goes high, it provides the output. Like, for the first clock pulse, pin 3 will provide you output; for the next pulse, pin 2 will provide output, and so on. After 10 pulses, it will again start from Q0 output.

• Clock Inhibit pin (pin 13) - It is used to switch the counter "on" and "off". If you want to switch off the counter, then pin 13 should be high. If it is high, it will ignore the clock pulse no matter how many times you press the switch, meaning the counter will not advance.

• Ground pin (pin 8) and Positive Voltage Supply pin (pin 16) - They are used to provide the ground connection and the positive voltage supply to the IC.

• Carry out pin (pin 12) - It is used to connect one or more 4017 ICs. The carry pin of the first 4017 is connected to the clock input of the second, and the carry pin of the second is connected to the clock input of the third, and so on. In our circuit we have used only one IC that's why we have left this pin.

• Output pins (pins Q0 - Q9) - It is used to receive the output in sequential manner. Like for first pulse pin 3 will provide you the output and so on.

References:

• http://www.engineersgarage.com/electronic-circuits/understanding-decade-counter-cd4017

The video embedded in this step is for educational purposes only. It is the property of its creator ASD82able, uploaded on YouTube. Check out his page here.

Step 6: The 386 Audio Amplifier

The LM386 is an integrated circuit containing a low voltage audio power amplifier. It is suitable for battery-powered devices such as radios, guitar amplifiers, and hobby electronics projects. The IC consists of an 8 pin dual in-line package (DIP-8) and can output 0.25 to 1 watts of power depending on the model using a 9-volt power supply.

Uses of LM386:

• The LM386 is one of the most common amps used in DIY guitar pre-amplifiers and sustainers due to its ability to run on a single 9V battery.

• The EasyEDA "Tesseract" Guitar Practice Amplifier is a versatile design based on the LM386 and features distortion and full-wave rectification effects.

• The well-known "Smokey Amp" created by Bruce Zinky uses an LM386 and is notable for being able to fit in a cigarette package.

• The "Little Gem" and "Little Gem MkII" are modified/cloned versions of the "Smokey Amp".

• The "Ruby" amp is a modified version of a Little Gem amplifier.

• The Marshall MS-2 and MS-4 miniature practice amplifiers use a single-in-line packaged NJM386 manufactured by JRC.

The 386 is useful for small speakers and wouldn't produce too much noise. If you are after a loud audio source, you can use an IC in the TDA20xx series like the TDA2003 (10 watt audio amplifier IC), TDA 2030 (20 watt audio amplifier IC), etc.

References

• https://en.wikipedia.org/wiki/LM386

Step 7: The Voltage Regulator

A voltage regulator is designed to automatically maintain a constant voltage level. A voltage regulator may be a simple "feed-forward" design or may include negative feedback control loops. It may use an electro-mechanical mechanism, or electronic components. Depending on the design, it may be used to regulate one or more AC or DC voltages.

Electronic voltage regulators are found in devices such as computer power supplies where they stabilize the DC voltages used by the processor and other elements. In automobile alternators and central power station generator plants, voltage regulators control the output of the plant. In an electric power distribution system, voltage regulators may be installed at a substation or along distribution lines so that all customers receive steady voltage independent of how much power is drawn from the line.

In my project, I have used a 7809 voltage regulator from the L78xx Positive Voltage Regulator Series.

I have used an additional Heatsink along with the voltage regulator just to prevent it from overheating. In case you are not interested in using a heatsink, do calculate and check the amount of heat that will be produced by the Voltage Regulator.

References

• https://www.youtube.com/user/Afrotechmods

• https://en.wikipedia.org/wiki/Voltage_regulator

Step 8: The Power Supply

The Power Supply I made consisted of a center tapped transformer, a full wave rectifier consisting of two diodes. I used capacitors to smooth the output and a L7809CV Voltage regulator to regulate the output voltage to 9 volts.

The two videos that I have embedded in my tutorial are by Afrotechmods. He talks about the diodes and the full wave bridge rectifier in the first one and about electrical transformers in the second one.

You can easily use a bridge rectifier instead of a full wave rectifier or use a bridge rectifier IC. I prefer using the 1N4007 diodes but you can use any diode that works out fine. I'd suggest using one in the 1N40xx series. To find out more about them visit this Wikipedia page.

If you're using a bridge rectifier, then a 0 - 12 v transformer will also work. You can also use transformers with different voltage ratings such as 9-0-9, 0-9, 6-0-6, etc. Then be careful about the minimum voltage required by the ICs. Also remember about the loss of voltage due to the voltage regulator and the minimum voltage required to make the voltage regulator function properly. You can also use a different voltage regulator if you like.

My power supply including the voltage regulator circuit uses the parts listed above.

Besides this if you just want to make life safe and easier, you may simply remove all the sort of complex stuff like the transformer, rectifier, voltage regulator, etc., and simply use a battery. A typical 6F22 9 v battery would be ideal for this job, but you can also use a 6 or 12 v lead-acid battery in case you're not too considered about safety.

References

• https://www.youtube.com/user/Afrotechmods

Step 9: The Transistor (Enabling the sequencer to step the sound of external Audio Sources)

If you see carefully at the bottom left of the schematic, you will see a BC547 NPN BJT (Negative-Positive-Negative Bipolar Junction Transistor) placed there connected to a few capacitors and resistors. You can use any similar transistor like a BC548 or 2N2222, etc., which should also work pretty much fine.

In the images above there is one of a single transistor amplifier, which you can edit to improve upon the circuit. You may also remove the tone generator, or the Atari Punk Console as you may call it, because with the transistor you can step the sound of pretty much any external audio source. Try experimenting around with the resistor and capacitor values around the transistor on the breadboard and use the ones which sound the best to you.

The videos above are a pretty good description of the transistor by Electro-Fogey (Doug Peter). You can google about the transistor for more information.

References

• https://www.youtube.com/channel/UCa5sVx7PWRIW2Dvvq...

Step 10: Breadboarding The Circuit

Breadboarding the circuit is quite helpful because it actually allows you to experiment and modify the circuit and you actually don't have to solder anything. It is useful in experimenting with the different resistor and capacitor values in audio circuits.

But there are some disadvantages too. Sometimes the thin leads of resistors and other components often end up shortening to parallel series of connections on the breadboard. The output audio sound can also be quite unusual and unpleasant if the resistors and capacitors are not properly connected. There can be loose connections in a breadboard which can actually drive you crazy when the circuit doesn't work and you end up checking the entire connection twice.

I built pretty much everything of the circuit on the breadboard. If your'e breadboarding, just build the sequencer up to three - four steps (like I did). It's enough and lets you add new things to the circuit. I used separate breadboards for different parts of the circuit. The pictures above only contain some of the parts of the circuits. Some things I had added while I was building it on the perfboard.

I also recommend you to check the datasheets for the various ICs and the transistor, in case you don't end up destroying them. I have attached the datasheets of all the ICs and the transistor in their respective steps.

Step 11: Shifting to the Perfboard

Now, you can build the circuit on a perfboard; you may etch your own PCB for this project if you like.

Some handy tips to be remembered:

• Be a bit careful about unwanted solder joints.

• Run a hobby knife between them after you have soldered everything.

• Take care that there are no dry solder joints on the perfboard. They have a higher resistance and can actually mess up in audio circuits.

• Take special care about soldering the ground connections properly.

• It's better using an IC Base and heat-sinks for the ICs just in case, so you don't end up burning them. However, if you are not using the three IC Bases and the Heat-sink, be careful about not overheating the ICs and damaging them.

I have used three pieces of perfboard for the project; you can build the entire circuit on a single piece of perfboard. I hadn't made the schematic properly at first. It was just that when I had been soldering everything, I came across a number of ideas and then finally assembled them on separate pieces of perfboard. I have soldered a number of male connectors on the perfboard for off-board components like potentiometers, switches, LEDs, etc.

Step 12: Assembling the Perfboard and off-board Components

After you've soldered everything in the perfboard, you can get into assembling the off-board components like the perfboard, the power supply, audio jacks, etc., in the electronics enclosure. For this project, you can make for yourself a wooden box, if you're good at woodworking. You can alternately 3D print a kind of box or something as the enclosure.

I just simply took an old cardboard box and put up everything in it. I assembled the things as:

• I had put the LEDs in the LED holders and drilled holes using a screwdriver and assembled the LEDs, switches, potentiometers and audio jacks.

• I had made the power supply in a plastic box. I had also assembled the speaker in a plastic enclosure. I strongly recommend you not to fix the speaker in the plastic enclosure since its sound is very awful and I have to use the headphones or some external speaker every time I use the sequencer. I fixed the plastic box of the power supply, the enclosure of the speaker, and the AC connector using nuts and bolts.

• I had pasted some cellophane paper or some sort of plastic like insulating sheet under the perfboards to prevent any short circuits. It also improves the quality of the sound. Cardboard is a type of material whose conductivity changes depending on the amount of moisture it contains. So, it was better to use one.

• I have used some pieces of perfboard as the GND and Vcc supplies for connecting them to various off-board components. I have also used one for connecting the outputs of the pulses of the 4017 IC.

• I had stuck the wires of the connectors together with some tape, just to ensure easy handling.

Step 13: Decorating the Enclosure

I'd consider this step as optional. If you're using an electronics enclosure or a wooden box, etc., you wouldn't actually need to decorate it much. But I had used an old cardboard box which was in a pure state of modification.

I had stuck all sorts of handmade paper and such on the box and put black colored tape on the edges just to prevent it from tearing. I have stuck a number of labels consisting of yellow paper all around the box. I had messed around with the paper at a couple of places; so I have used a black permanent marker to just hide them all.

If you're good in woodworking and have made a wooden enclosure, you can actually do a lot of things with it. For example, you can polish it or paint it or cut it and stick a sheet of sun-mica on it.

I'd recommend you just try brainstorming a few ideas and get along making it on your sequencer.

Step 14: Making Music

Now, after all that you should have gotten everything about the sequencer which would be ready for you to compose your own rhythmic riffs. It's important to remember that with my schematic, you can actually vary the pitch of each individual step while using the inbuilt tone generator. You wouldn't be able to do so with the external audio source; you'll just be able to vary its feel, timing and the duration of each pulse. Check out the above three videos that demonstrate this awesome sequencer.

Well, if you're a musician like me, I can explain it to you in terms of time signatures. For example, if you have the sequencer on up-to four steps (that's the time signature 4/4), you can actually vary its pulse, or counting as you say it; like at first the sequencer is going: one, two, three, four. You can vary it as: one and two, three, four; then one and two and three, four; then one and two and three and four and, etc. You can also adjust the dynamic things, like when to get the accented strum/stroke in the rhythm.

All these things can actually be done using the sequencer, and you can also get just the drum-like beat by turning on/off (I don't exactly remember) the switch at the place where there's a capacitor at the base of the transistor.

Well, now I guess you must have done everything with the sequencer that you could have done to make it look pleasing and work better than anything else. I've typed a lot by now, and I think that now I must close up this tutorial. All comments, suggestions, corrections, etc. are welcome. Do share with me your ideas if you built anything new in the sequencer. I'd be really happy to see you yourself making it.

Thanks a lot for reading my tutorial. Be sure to check out my other tutorials here. Have a nice day and take care.