White Noise Generators

Audio Frequency White Noise Generator

This handy noise generator produces white noise from well below 1 Hz to over 40 kHz by amplifying the noise from two resistors. Use good quality metal film resistors for consistent results. This design uses an older LF356 JFET op-amp and many others will work. See the noise calculations to determine if another op-amp is suitable. The best choice of op-amp will be an FET type.

The noise generator is built into a small aluminum mini-box:

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White Noise Generator for Audio through 25 MHz

This noise generator amplifies the noise from a resistor using a fast op-amp to provide a very predictable and flat noise spectrum from audio up to about 25 MHz. This older design uses an obsolete CLC425 but newer op-amps will work well. The noise calculations are included so that the experimenter may perform the calculation for newer amps.

I make oscillators so I have lots of oscillator cans but any metal enclosure will work. Not shown in the schematic are a couple of 6.8 volt zeners in series with my +-12 volt supplies to drop the voltage to near +-5 volts for the op-amp.

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Broadband White Noise Generator found in Surplus Sale

Here's an odd noise source I found in a surplus purchase. It passes current through a 1N21 diode to generate broadband white noise. The level is pretty low.

It's built into an ordinary aluminum Bud Box:

It's flat to 500 MHz and becomes too low to measure with my analyzer above 1 GHz.

Ideas from this Project