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Illuminated LED Rhythm Sequencer
A LED sequencer, mirroring the beat of audio
9V Battery-powered portable unit
Circuit diagram
Components:
- R1 10K 1/4W Resistor
- R2,R3 47K 1/4W Resistors
- R4 1K 1/4W Resistor
- R5,R6,R7 100K 1/4W Resistors
- R8 820R 1/4W Resistor
- C1,C3 100nF 63V Ceramic or Polyester Capacitors
- C2 10µF 50V Electrolytic Capacitor
- C4 330nF 63V Polyester Capacitor (See Notes)
- C5 100µF 25V Electrolytic Capacitor
- D1 1N4148 75V 150mA Diode
- D2-D11 5 or 3mm. LEDs (any type and color)
- IC1 LM358 Low Power Dual Op-amp
- IC2 4017 Decade counter with 10 decoded outputs IC
- M1 Miniature electret microphone
- SW1 SPST miniature Slider Switch
- B1 9V PP3 Battery
- Clip for PP3 Battery
- Additional circuit parts (see Notes):
- R9,R10 10K 1/4W Resistors
- R11 56R 1/4W Resistor
- D12,D13 etc 5 or 3mm. LEDs (any type and color)
- Q1,Q2 BC327 45V 800mA PNP Transistors
- Q3 BC337 45V 800mA NPN Transistor
Device purpose:
The basic circuit illuminates up to ten LEDs in sequence, synchronized with the rhythm of audio picked-up by a small microphone. The expanded version can control up to ten strips, comprised of up to five LEDs each, supplied by a 9V power source.
Circuit operation:
IC1 amplifies approximately 100 times the audio signal captured by the microphone and drives IC1B functioning as a peak-voltage detector. Its output pulses are aligned with the peaks of the input signal, and in turn, they clock IC2, a ring decade counter capable of controlling up to ten LEDs in sequence. An auxiliary circuit enables the management of up to ten strips, constructed from five LEDs each (maximum), using a 9V supply. This circuit utilizes a 10mA constant current source (Q1 & Q2) common to all LED strips and a switching transistor (Q3), which manages a strip made up of two to five series-connected LEDs. Consequently, one transistor and its base resistor are needed for each strip utilized.
Notes:
- The sensitivity of the circuit can be adjusted by modifying the value of R4.
- C4’s value can be varied between 220 and 470nF to alter the circuit's responsiveness to audio peaks.
- Incorporating the additional circuit, only one item for R10, R11, Q1 and Q2 is required to manage up to ten LED strips. Conversely, one item of R9 and Q3 is necessary for each strip chosen.
- Each R9 input must be connected to IC2 output pins, replacing the LEDs D2-D11 shown. R8 must be omitted.
- If a lower number of LEDs or LED strips is desired, pin #15 of IC2 must be disconnected from ground and connected to the first unused output pin. For example:
- If five LEDs are being used, pin #15 of IC2 must be connected to pin #1. If eight LEDs are used, pin #15 of IC2 must be connected to pin #9, and so forth.
- The circuit’s current draw is approximately 10mA.
- To utilize a wall-plug transformer-based power supply instead of a 9V battery, a supply of 12V can be applied, allowing for the operation of up to six LEDs per strip, or a 15V supply allows up to seven LEDs per strip.
circuit from http://www.redcircuits.com/