The stepped tone generator , also known as the “Atari Punk Console” (APC), is a makeshift device developed by Forrest M. Mims , a creationist and radio amateur, described in “Engineer's Notebook: Integrated Circuit Applications” ( the publishing house of the 1980s Radio Shack store and the Engineer's Mini-Notebook - 555 Circuits (published by Siliconcepts) in 1984 [1] .
There are several models of radio designers for assembling step-tone generators.
Content
Device Device
The device is made on an integrated circuit type 556, which is a dual version of the known timer 555 [2] . You can apply two single timers, including domestic ones, such as KR1006VI1. On the first timer, a tone generator is made — a tunable multivibrator ; on the second, a one-shot, triggered by pulses from a tone generator. It is important to note that the launch of the one-shot by the next impulse produced by the tone generator occurs only if by this time the one-shot is already completed the formation of the previous pulse. It is this feature of the device that explains the relative complexity of the sounds generated by it with such a simple structure (as will be indicated below).
The front panel of the device is equipped with three variable resistances:
- Regulator of the frequency of the tone generator;
- The regulator of the pulse duration of the one-shot;
- Volume control.
Devices with a similar principle of action can, if desired, be made on the basis of a rectangular pulse generator and a one-shot made on any other elemental base (TTL or CMOS IC, crystal triodes, electron tubes, etc.). The original circuit is also sometimes modified, in particular, two identical instruments and a mixer are placed in the same housing, mixing their signals, and sequencers are added. Very often, the device is equipped with a linear output, as well as one or two outputs for headphones. Sometimes, for the purpose of joking with respect to the term “Atari punk console”, the circuit is assembled inside the case from some small Atari peripheral device: a mouse, a joystick.
Disputes about how the EMR is a step-tone generator - analog or digital - are meaningless. This EMR is hybrid, that is, analog-digital. It contains signals of both analog and digital character. Both the multivibrator and the one-shot in the EMI produce discrete, that is, digital signals, and the one-shot, moreover, is controlled by such a signal. But the voltage on the timed capacitors voltage varies smoothly - this is an analog signal. In addition, there is no fixed time sampling in the step-tone generator - the frequencies of the oscillators also change smoothly, which is also a sign of an analog device.
Instrument Playing Techniques
There are two main methods of playing on a step-tone generator. The first of these, called “ sweeping of frequency ”, consists in changing the frequency of the tone generator at a constant single-pulse time, while a rumble is heard that resembles the sound of a two-stroke engine when its rotational speed changes. In certain positions of the regulator, there are also howls. The second, called “ sweeping of width ”, is to change the pulse duration of a single vibrator at a constant frequency of the tone generator. The sound generated by this is especially beautiful, because it is the same note that jumps between octaves, and changes timbre between the movements (while the one-shot plays the role of a frequency divider with a variable division factor). It was this sound that gave the design the name “step-tone generator”. More complex sounds occur when combining these techniques, that is, the simultaneous adjustment of both parameters.
How does the one-shot divider the frequency of the tone generator, if it does not contain anything similar to the counter? Let's draw the following analogy. If to lower the next coin into the machine with sparkling water, without waiting until it completes the previous cycle of pouring the drink, then it will not react to it in any way. The one-vibration is also “deaf” to the trigger pulses that arrive before the completion of the formation of the next output pulse. Therefore, if you set the one-shot for the pulse duration exceeding the period of the pulses generated by the multivibrator N times, then it is logical that it will not be triggered by each of them, but approximately by each N-th, and divide the frequency by the same amount. As such frequency dividers, you can use not only one-shot, but also blocking-generators. This is exactly what has been done, in particular, in the lamp versions of instruments for checking clocks (PPC). Since a one-shot or blocking generator, unlike a trigger, is capable of dividing the frequency by a number significantly higher than 2 (for example, 10), in the same frequency converter the generator, made on just one lamp, replaces several triggers, each of which contains two lamps . With normal use, the disadvantage of such a frequency divider is the need to adjust the division factor and the dependence of the latter on the frequency of the input signal. In this musical instrument, this feature turns into an advantage: the division factor is easy to change without any switch in the circuit.
Stepwise tone generators are used, in particular, by some performers of 8-bit music. Sometimes when recording the sounds of a step-tone generator, they are subjected to artificial reverberation.