Product description
Electrokit EK041 is a digital noise generator based on a 97-stage shift register, LFSR (Linear-Feedback Shift Register). It generates a pseudorandom digital pulse train with an adjustable clock frequency. Suitable for applications such as sound synthesis, electronic sound effects, digital circuit testing, signal processing, and education in digital electronics.
The noise generator is built around two shift registers in which two steps in the registers are combined by an XOR gate and fed back to the first step. This produces a pulse train that repeats extremely rarely and is perceived as pure noise.
An LFSR is not a source of “true” noise that can be used for cryptography, but it works well for generating test signals or as a general-purpose noise source within larger circuits.
The clock frequency is adjustable from approx. 5kHz up to 50kHz using the supplied trimmer potentiometer. If greater precision is required, a multi-turn trimmer can be fitted instead. The generator’s frequency range can be changed by replacing capacitor C5 with a higher capacitance (lower frequency) or a lower capacitance (higher frequency).
Note that it takes a moment for all 97 stages of the shift registers to fill with an even mix of ones and zeros. Until they do, the output is more or less regular, which is heard as a more or less noisy tone following the clock frequency. At worst this takes a few seconds, so let the generator run briefly before use.
With the generator’s 97 stages, a total of 2⁹⁷−1 different states can be produced. At a clock frequency of 20kHz this means the sequence at the output will not repeat for 2.5 × 10¹⁷ years, or roughly 18 million times the age of the universe.
Specifications:
- Supply voltage: 3 – 15 V
- Current consumption: ~1.5 mA (at 12 V)
- Dimensions: 40 x 36 mm
- Mounting holes: 35 x 31 mm