Schmitz White Noise Generator

I just checked, and the schematic had been taken from Rene’s library :+1:

It’s a great resource :+1: :sunglasses:

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I added the header so I could just use a standard (Doepfer standard) ribbon cable :grinning:

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Your post got me thinking, I have a board out of a radar signal simulator… I think that it has a white noise generator on it, it’s got a boost circuit to output 12 volts and a couple of 555s, plus a big chip that seems to be connected to a modulator in pin on the radar unit its self.

Could rig it up to a speaker and see what comes out when activated… may be a nice source of white noise?

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The MM54C221 is a one-shot pulse generator so odds are it generates nice pulse trains, not any form of noise, but it seems like a fun subject for a bit of circuit bending :+1:

(the MAX642 is a 5V 12V (see below) step up switching regulator, so I assume BATT is one or maybe two 1.5 cells?)

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The batt is a 6 volt dry cell pack… Yes, was thinking of bending the circuit, possibly got another unit coming next week with an identical board. This thing is wired up with teflon coated braided silver wire.

I made a torch out of one unit, left another as a radar source, maybe the third unit can have a speaker instead of a LED cluster?

Apologies for veering off the topic somewhat…

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also in this thread :wink:

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Ah, right – the MAX642 is 12 V, not 5 (looked at the wrong row). Datasheet says the regulator won’t regulate if you get within a diode drop of the target output, but 6V is plenty of margin :slight_smile: (but you may be able to power it with 12 V if you add a couple of 1N400x diodes in series on the way in)

I have no idea what frequencies this would output as is, but the circuit is simple enough that you could calculate that from the component values. Powering it up and looking at the output sounds easier, though :grinning: You may have to replace the 555 timing capacitors to bring things into the audible range, and the next step is then to replace the timing resistors with pots. You can also mess around with the 54C221 timing components. A bit like a mil-speced dual Atari Punk Console :cool:

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This would be a Nato Punk console, as it has a proper Nato number… as it was used for testing Lynx helicopter radars apparently! The 555s are easy enough to get pinouts and circuit diagrams for. Could just draw a diagram… Got a nice little self contained mono amp for just such a project! Was going to chuck the board out, but spotted the 555s…

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that is some pretty cool surplus stuff , it will be fun to see what you do with it .

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I made a torch with the empty shell, recycled LED lamp turned to fit on my lathe, recycled lithium cells from a broken bike battery re-welded together in a funny shape to fit the case and some standard DC DC converters plus a latching solenoid switch unit and an extra LED indicator lamp. Still got the original circuit board laying around in the parts box.

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This is mine. It was the first diy build I made that wasn’t a kit. I made a Youtube clip here at the time: https://youtu.be/ypZVMgOxab0

It’s getting surgery at the moment - I’m adding a non-inverting opamp at the end to increase the output level.

I hope it still works afterwards :joy:

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Cool! Welcome to the forum, @Mcshafty!
Is it using a floating-pin transistor with a hex inverter as an amplifier?

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Cheers for the welcome.

I don’t think it’s either.

I tried adding a standard non-inverting opamp circuit (TL072 4.7k/47k) after the output of the noise circuit.

I found that the 12v version of the layout at the top of the the post to be very quiet. I did build a separate amplifier module using a non-inverting opamp schematic and that worked so I thought it would be good to combine them.

Anyway, It didn’t work :angry:. But I’ve only been doing stripboard layouts for a few months and I’m learning as I go. It could be poor soldering, a misplaced component or a fundamental design flaw. I’ll revisit it in a few days with fresh eyes.

In the meantime, I built this “Roland System 100m” LFO (that does work) to play with.

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Hello guys, I’m having issue whith this schematic. No white noise on the output, double checked everything. Maybe it’s because I’m using ceramic capacitors ? Anyone have an idea ?

Check the supply rails. If they’re as expected, check that you’ve mounted the transistor the right way around, and try a few different transistors – not all of them provide the same noise levels.

Well, all electronic circuits generate some noise, so (assuming you’ve powered up the circuit) I’m pretty sure the problem here is the noise level, not the noise itself :grinning:

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I’d definitely recommend building any noise source on a solderless breadboard first so you can try several transistors. Some will work much better than others. Once you’ve got one that works well you can transfer the circuit to a stripboard.

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If one has 3-pin female headers, you could solder that in, and pop the transistors in and out.

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Thank you guys ! I soldered a 3pin header and was able to try different transistor.
I had more luck with a 2n3904.
I will definitely remember your advice and build noise on a breadboard before soldering.
I’m amazed by the difference between two transistor by the way.
Next step Sample and Hold !

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Surely all you need is two pins. But for the permanent build I’d rather have the transistor soldered in. In addition, you might want to try varying the resistor on the emitter.

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I was just meaning in general use some female headers if you are going to plug in many things. I assumed 3 since transistors usually have 3 pins. I know a lot of schems clip the middle leg, but youknowwhatimean.

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