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 Post subject: General radio 1390 random noise generator
PostPosted: Jan Sun 12, 2020 5:15 am 
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Joined: May Wed 11, 2016 2:18 am
Posts: 367
Location: springvalley ohio
Does anyone use one of these?
Curious usefulness of it?
Thanks


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 Post subject: Re: General radio 1390 random noise generator
PostPosted: Jan Sun 12, 2020 5:11 pm 
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Location: Roanoke, VA
I don't own one, but do own a couple of other Gaussian noise generators. They have many purposes, such as room acoustic measurements, microphone and loudspeaker measurements, filter measurements, and bandwidth comparisons. Nowadays Gaussian generators are generally used in conjunction with real time analyzers of 1/3 octave or better resolution.

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 Post subject: Re: General radio 1390 random noise generator
PostPosted: Jan Sun 12, 2020 9:56 pm 
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Joined: Jun Sun 23, 2013 9:03 pm
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Location: Canandaigua, NY
I have and use one for audio work, but quite often I grab a much smaller battery operated solid state one I built when the National noise generator chip was available. I put a pink noise filter on that. You can add same for the GR unit as their schematic is available somewhere, if you can't find a factory one. Wow, I'm dating myself- that was quite a while ago.


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 Post subject: Re: General radio 1390 random noise generator
PostPosted: Jan Mon 13, 2020 2:14 am 
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Joined: May Wed 11, 2016 2:18 am
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Location: springvalley ohio
I appreciate both responces.
I did download the manual.
Curious what that part number of the national ic was.
Thanks


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 Post subject: Re: General radio 1390 random noise generator
PostPosted: Jan Mon 13, 2020 2:25 am 
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Location: springvalley ohio
I found it
http://www.discovercircuits.com/N/noisegen.htm


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 Post subject: Re: General radio 1390 random noise generator
PostPosted: Jan Mon 13, 2020 3:05 am 
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I have a little small solid state Heath white / pink noise audio generator that runs on a battery. It was paired with an audio analyzer that was unrepairable, as I recall. Frankly I do not recall ever using it for anything at all. But when I ever need it.........

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 Post subject: Re: General radio 1390 random noise generator
PostPosted: Jan Mon 13, 2020 6:50 pm 
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Joined: Jun Sun 23, 2013 9:03 pm
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Location: Canandaigua, NY
Wandering OT, you can do a rather nice noise generator by breaking down the B-E junction of common transistors and amplifying the result. With careful selection they can be good far into the RF region. A common application is an antenna noise bridge. I also have the GR higher frequency noise generator, 1383, that goes to 20 MHz.


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 Post subject: Re: General radio 1390 random noise generator
PostPosted: Sep Fri 03, 2021 6:51 pm 
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Location: Littleton, MA
The manual for the General Radio 1390-B Random Noise Generator is readily available. I've just acquired the earlier version, the 1390-A. The -A is missing the -B's output attenuator, and has other minor differences. Does anyone know where I can find a scan of the manual for the 1390-A?

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 Post subject: Re: General radio 1390 random noise generator
PostPosted: Sep Fri 03, 2021 8:56 pm 
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Joined: Jun Sun 15, 2014 5:37 pm
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Location: Montreal, Quebec
Those white noise ICs are just long shift registers with feedback. You can do it with logic ICs. Don Lancaster wrote a number of times about pseudo random sequencers like this.


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 Post subject: Re: General radio 1390 random noise generator
PostPosted: Sep Sat 04, 2021 3:46 am 
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Location: Liberty, Missouri
I've also owned a couple of them over the years. There are numerous circuits out there for rolling your own using a very few ICs.

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 Post subject: Re: General radio 1390 random noise generator
PostPosted: Sep Sun 05, 2021 11:39 am 
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Joined: Jan Fri 27, 2017 8:41 pm
Posts: 367
Location: Springwater, NY
I use the GR devices as a source of random numbers for a variety of experiments. I've built and tested several versions similar to this:

Attachment:
Noise Generator Tube Schematic.jpg
Noise Generator Tube Schematic.jpg [ 135.2 KiB | Viewed 243 times ]


I've also built and tested simple devices based on atmospheric noise....just turn on the radio and capture the audio, followed by some signal processing. Here is a link to an interesting site based on QRN:

https://www.random.org/

Another interesting site, which uses radioactive decay:

https://www.fourmilab.ch/hotbits/

73 Dean


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 Post subject: Re: General radio 1390 random noise generator
PostPosted: Sep Sun 05, 2021 3:13 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Westminster, CO, USA
Mikeinkcmo wrote:
I've also owned a couple of them over the years. There are numerous circuits out there for rolling your own using a very few ICs.

Mike,

Yes, you've owned one because you sent it to me for which I am still grateful! I found it very useful when used in conjunction with my old Tek 492 spectrum analyzer to look at filter response curves. I have since upgraded to a Micronetics NOD5200. The GR stops at 20Mhz and I wanted to go wider. Also, the NOD is "calibrated" so it is more useful when looking at noise floor and such. I still have the 1390 but I need to work on it to find an intermittent that makes the output jump up and down.

Tony

Oops, sorry. You sent me a 1383. Oh well, it's been a while since I looked at it. Still made good use of it!

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 Post subject: Re: General radio 1390 random noise generator
PostPosted: Sep Mon 06, 2021 4:15 am 
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Joined: Oct Sun 15, 2006 12:57 pm
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Location: Liberty, Missouri
Hi Tony, Glad to see you got some use out of it.

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