need some guidance (guitar signal to voltage)

[FUZZZZzzzz]

I want my guitar signal to trigger a voltage output for which I can set a sensitivity. I know there are a lot different pickups and output levels so for a wider use this is probably recommmended. The harder I strum the more voltage output I generate. (say something between 0 volt when I do nothing and a max of 9 volt strumming hard) How can I achieve this? Can someone put me in a right direction?

I hope the question is clear, because finding the right search keywords is really hard for me at the moment.

thanks!

[Brisance]

a rectified voltage amplifier with a smoothing cap?

[deadastronaut]

wouldn't  a lm3914/5/6 vu display ic do this?...

or do i need more coffee..

[samhay]

>I hope the question is clear, because finding the right search keywords is really hard for me at the moment.

Clear enough. Look for 'envelope detector'. They can get fairly complicated depending on exactly what you need the envelop / signal to do.

[PRR]

> lm3914/5/6 vu display

That gives a 0-10 digital (LED) output.

You "could" design a resistor network to compute a voltage from the digital bits. But the '3914 isn't intended to work that way, so it may be a lot of resistors. And the '3914 is intended to *take* an "envelope detected" signal (although being hi-gain uni-polar, it does dance with raw audio).

There are better ways than '3914, unless the LEDs or the thresholds are needed in other parts of the project.
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> trigger a voltage output for which I can set a sensitivity.
> The harder I strum the more voltage output I generate. (say something between 0 volt when I do nothing and a max of 9 volt strumming hard)

You are asking for two different things. Do you want ON when signal hits 200mV (adjustable)? Or do you want a proportional voltage?

If you want ON when signal exceeds 200mV, you only need a Comparator. Set one input at zero V DC plus audio. Set the other input at 200mV. The output will change state when the live input crosses 200mV. The 200mV can be a pot across 0V-1V so you can dial-in the setting. Problem is that inaudible spikes may false-trigger, and steady loud tone will on/off/on/off at 440Hz (whatever).

A more musical way is the envelope detector followed by a comparator. This filters-off fast changes and follows the swell/decay of speech/music.

If you only want a zero-9V linear output, envelope detector and DC amplifier.

[FUZZZZzzzz]

thank you  for sharing your knowledge.. mind you, I'm not anywhere near your level of skills.

What I would like, ideally is to trigger a small dc motor. When I play.. the dc motor plays along and the hard I strum the faster the motor runs. It's part of a mechanic pedal I have in mind.

[DavidRavenMoon]

Craig Anderton had some circuits like this published in Device.

[FUZZZZzzzz]

Cool! I had to google, but by device you probably mean this newsletter
http://hammer.ampage.org/?cmd=lt&xid=&fid=&ex=&pg=11

Any idea what it was called

Craig Anderton had some circuits like this published in Device.

[PRR]

> When I play.. the dc motor plays along and the hard I strum the faster the motor runs.

OK. Put a full-wave bridge rectifier across your Speaker Output, AC legs to speaker, + and - legs to your motor.

Believe it or else, I have seen this done and work fine. Home hi-fi amps must pass a heavy heat-test but should also sit silently in normal operation. I was testing a Sansui or something. There was a fan, it didn't run, the amp wasn't hot, so I didn't care. In testing, the fan DID run on musical peaks. Louder made faster. I traced the fan circuit and it was as I say above. In extreme home use the fan would barely blip. In full-power testing it made a good breeze, less as the test power was backed down. In guitar work you usually run very near (or past) full power most of the time. The motor will probably run most of the time.

Motor voltage has to be considered. A 25 Watt into 8 Ohms amplifier gives about 14 Volts. A "12 Volt" motor is a good first try. Use a low-price motor..... heavy headbanger sets might burn it up. You want the motor nominal power much less than the amplifier power. In this case, say 2 or 3 Watts, or 12V @ 0.2A (200mA). The larger PC case-fans are in this range. A car heater-blower is far too hungry.