BEAM Sonic

Description: BEAMSonics is an innovative circuit designed by Wilf Rigter. Its primary function is to filter incoming sounds and count high-pitched pulses, such as whistles and beeps. Upon detecting a specified number of beeps, it responds with a sound of its own. When left idle, it will intermittently produce a beep to explore its environment. A comprehensive description of its operation is provided at the bottom of the page. After constructing several Sonic circuits for a project, the design was modified for greater flexibility and additional features, as suggested by Wilf. The new design accommodates various inputs, including an electret microphone and light sensors, and features an alternative output stage capable of driving a coil or other inductive loads. The printed circuit board (PCB) supports multiple inputs and outputs, with components color-coded for easy identification: red for standard parts and piezo output, green for coil driver output, yellow for dynamic microphone input, and blue for electret microphone input. The yellow dotted oblong and square markings indicate locations for PCB strip sockets or pins. Space is allocated for two preset potentiometers to control the output oscillator frequency (pitch) and pulse duration for the coil driver option. For Wilf's schematics and an explanation of the circuit's operation, refer to the bottom of the page. The SONIC circuit functions as a sound processor that generates a chirp in response to multiple chirps or sound packets from external sources, such as other chirpers or human whistles. This concept, based on Bruce Robinson's idea, seeks a "killer application." Meanwhile, this article serves as a platform for discussion and testing related ideas, such as integrating sound sensing and processing into a beam robot. The project incorporates several typical BEAM subsystems and components that have been utilized in various applications. The circuit employs a single 74HC14 chip, available from suppliers like Solarbotics, along with a few other components easily sourced from Radio Shack, facilitating an accessible starting point. Unlike the SMART HEAD, which required meticulous tuning for optimal results, the SONIC circuit's component values are not critically sensitive, allowing for substitutions or adjustments without significant issues. The attached schematic illustrates that the electret microphone signal is amplified approximately 2000 times using two AC-coupled transistor amplifiers (Q1 and Q2). Small coupling capacitors serve as high-pass filters, eliminating low-frequency "rumble" sounds and vibrations that could interfere, particularly in mobile applications. The microphone amplifier is designed to detect low-level sounds, such as chirps or beeps, from a distance of 5 to 6 feet. The circuit filters out clicks and noise pulses shorter than 10 milliseconds from incoming sounds. The Nu stage produces a single positive output pulse that lasts at least 10 milliseconds, corresponding to the duration of the incoming sound pulse. Resistor RA, in series with diode D1 and parallel to resistor RD, establishes the Nu "attack" time, which defines the minimum required input pulse duration. The parallel resistor RD sets the characteristics of the circuit, ensuring functionality and responsiveness to sound stimuli.BEAMSonics is a clever little circuit designed by Wilf Rigter. It`s central function is to filter incoming sounds and count high pitched pulses, whistles, beeps etc. When it hears a certain number of beeps it will respond with a noise of its own. If left on its own it will ocasionally produce a beep anyway, just to see what else is out there. WIlf s complete description of how it works can be found at the bottom of the page. After building several sonics circuits for a project I decided to rework it into a more flexable design with added features, as suggested by Wilf. The new design allows for a variety of inputs. As well as an electret mic so you can use light sensors, it also incorporates an alternative output stage to the standard piezo sounder that will drive a coil or other inductive load.

This PCB allows for several inputs and outputs with the relevant components marked in different colours. Red is for standard parts and a piezo output, Green for a coil driver output, Yellow for dynamic mic input and Blue for an electret mic input.

The yellow dotted oblong and square markings are for PCB Strip sockets or PCB pins. Space is provided for two preset pots that control the output oscillator frequency (Pitch) and the output pulse duration for the coil driver option. For Wilfs schematics and an explanation of how it works see the bottom of the page. The SONIC circuit is a sound processor which generates a chirp if it receives several chirps (or other sound packets) from external sources like other chirpers or human whistles.

It`s function is based on a concept by Bruce Robinson and it is one of those projects that is looking for a "killer application". In the mean time this article is presented here for your enjoyment, for discussion and a test platform of related ideas eg adding sound sensing and sound processing to a beam bot.

The project combines several typical BEAM subsystems and components which have been used for many other applications. The circuit uses a single 74HC14 available from Solarbotics, etc. and a handful of other parts readily available from Radio Shack making it easy to get started. Unlike the SMART HEAD which required careful fine tuning to get results, the SONIC circuit component values are not particularly critical and you may substitute or adjust values to suit.

This will change some circuit parameters but nothing`s going to "hang up" and cause frustration. As shown in the attached schematic, a electret microphone signal is increased by a factor of about 2000 with two AC coupled transistor amplifiers (Q1-2). The small coupling capacitors provide a high pass filter function which strips off any low frequency "rumble" sound and vibration which could cause problems for example on a moving robot.

The microphone amplifier is a sound receiver, sensitive enough to pick up a low level sound, ie chirper/beeper, 5 or 6 ft away. Clapping your hands or minimum delay between sound pulses. The Nu filters clicks and noise pulses shorter than 10ms from the incoming sound. The Nu stage produces a single positive output pulse which is at least 10ms and as long as the duration of the incoming sound pulse.

Resistor RA, in series with diode D1 and in parallel with resistor RD, sets the Nu "attack" time ie the minimum required input pulse duration. The parallel resistor RD setsh D4 and the 1M resistor