Need Simple Noise Gen.

Hey I need a very simple noise generator.
Just something I can hookup to a momentary switch an generate any noise with an adjustable decay at 1.5V or something close to line lievel.

Reason:
My light trigger works on an Audio sense input. I'd like to have a manual mode and trigger the lights.

Thanks
-ChuckD

> very simple noise generator. ... any noise with an adjustable decay... My light trigger works on an Audio sense input.

"noise" or "any sound"?

What is this adjustable decay? Do the lights care?

Take a 1.5V battery and apply it to the trigger input. If you get a trigger every time you make the connection, put it in a box with a button.

If it really needs tone/noise audio, or a decay, then it gets trickier....

Hmmm

DC offset may work as you say.
Not sure I thought I actually need an audiable tone.

Let me try that tonight

-Thanks

-ChuckD

> DC offset may work

Not DC offset. When you connect the 1.5V battery it is identical to the beginning of a 1.5V square wave. If the trigger is trigger-happy, it should consider that as "something" and do its thing. It does not need to know that the "square wave" is (if you leave it connected) infinitely low frequency, it just needs to notice that a BIG "square wave" has started.

One problem: when you disconnect the battery, that is also a square wave start, of the other polarity. So you may get one trigger when you press, another when you release. That may even be good for rapid fingering! Probably the trigger has a post-trigger time period when it will not respond to another trigger (otherwise it would stay triggered constantly for organ pedal drones), so rapid tapping would give one trigger per tap. And the trigger may even be polarity sensitive, which would make it trigger one way and not the other.

Put about 2K resistance in series with the battery, just to limit current in case they did something dumb on the trigger input.

That totally worked!!
I didn't put a 2k in series with it yet but I think I should just to be safe.

Thanks a bunch!! Thats is the easiest solution possible, which means less things to go wrong. What a great solution.

I must do some research as to why the square wave is produced. I never heard that before.

-ChuckD

> why the square wave is produced.

Connect the 1.5V battery and loose wire to (someone else's) Line Input. Tap the battery. The amplifier will amplify the 0V to 1.5V transistion to a 0V to 30V and apply it to the speaker. The speaker will instantly jump from idle to extreme excursion, making a BIG "Thump" (and possibly jumping right out of its frame). (Actually: apply the 1.5V battry directly to a speaker: this is safe and produces a small but very audible thump.) Keep tapping, get a beat going, ain't a lot different from some bass drum tracks.

What you hear when pulsing a speaker is highly colored by the speaker. The actual sound is a big "tic" that starts as a high pitch but as it goes on includes all lower frequencies. If everything were DC-capable it would have all tones from over 20KHz all the way to DC. A real battery will die of old age, so you get a roll-off at about 1 cycle per year. Real amps will decay DC signals at a few Hz (some will shut-down if DC lasts longer than a 20Hz wave). So more of a tic/thud.

Obviously your trigger-box is too simple to make such fine distinctions. Zap it, it thinks it is the start of a bass-drum head motion, and it fires off the lights.