How to make a noise generating circuit?

[dumborambo]

I AM IN PROCESS OF DESIGNING A NOISE GENERATOR. However I am not able to find a circuit that is made of discrete components for creating a noise. The noise is to be used in mobile jammer device, a part of my research project. Can any one help me with schematic or some link.

 

[steadymind]

To use as a mobile jammer, you want to create a circuit with a strong signal power and feed input data from long pseudo-random number generator. the random number creates the "noise" and the signal power and frequency the jamming.

 

[dumborambo]

How can I do that? please guide me

 

[steadymind]

https://www.edaboard.com/threads/32079/

see the above threads. i haven't. built one so don't know the gotchas in the design. i wanted to point you that it is not exactly a noise generator. cheers.

 

[thylacine1975]

Heya dumborambo,

Aye, the scheme described by steadymind works a treat... I built a transmitter that could be used as a jammer based around this concept a handful of years ago. Apologies for the atrocious quality pic, but here's a photo of the prototype and a copy of the relevant page from my notebook:



Unfortunately I can't seem to locate the schematic I would have sketched in more detail... but the manufacturer's application notes associated with each of the devices I've indicated would be all you need to duplicate it, since there was nothing particularly special about the design. This circuit was designed to broadcast > 25 MHz noise centred on 947.5 MHz. A 947.5 MHz oscillator is BPSK phase modulated by a (bandlimited, i.e. filtered) PN sequence generated by a linear feedback shift register (LFSR) sequence generator. I can't recall the exact details of the PN generator, but the following link will provide you with more than enough background: PN (Pseudo Noise) Codes from Spread Spectrum Scene Online

Following modulation, I subjected the tiny mixer output signal (< -10dBm) to a chain of amplifiers, beginning with a minicircuits MAR-3, followed by a power amplifier section hacksawed out of a commercial 900 MHz FM transmitter (LIN900T) consisting of an OM370 CATV distribution amplifier and MRF581 power transistor. In order to achieve a potentially useful power spectral density, I fed the (filtered) output from these drivers into a (heatsinked) Motorola MHW820-3 PA module to yield ~18 Watts of wideband 'noise' (and consume lots of power... ~ 3.5 A at 12V)

Good luck

 

[drkirkby]

I AM IN PROCESS OF DESIGNING A NOISE GENERATOR. However I am not able to find a circuit that is made of discrete components for creating a noise. The noise is to be used in mobile jammer device, a part of my research project. Can any one help me with schematic or some link.

You can get special noise diodes which have a well defined noise response, but I assume that's not critical to you. Any high speed diode will generate noise if you supply a sufficiently high voltage to cause avalanche breakdown. A normal zener diode will too, though power devices will be limited in frequency response. Just follow that with an amplifier.

Dave