33 replies to this topic

[Robot]

Old Guy, on Feb 26 2010, 05:15 PM, said:

I've used the Frequency Multiplier circuit here with some success: http://www.bluebelld...m/HobbyHelp.htm

Useful as long as the input device senses the low Hz, to begin with.

[Robot]

Old Guy, on Feb 26 2010, 05:15 PM, said:

I've used the Frequency Multiplier circuit here with some success: http://www.bluebelld...m/HobbyHelp.htm

Holy smokes! I'm lovin their stamp board. Added to my, buy next month list.

[Old Guy]

Robot, on Feb 26 2010, 05:14 PM, said:

Useful as long as the input device senses the low Hz, to begin with.

Yes, but not all that difficult. There are several solutions available to the hobbyist. From the lowly Rat Shack electret to 15-inch subwoofer drivers. All can produce different but usable results.

My most recent inspiration: http://www.jclahr.co...iezo/index.html

[Robot]

Old Guy, on Feb 27 2010, 10:42 AM, said:

Robot, on Feb 26 2010, 05:14 PM, said:

Useful as long as the input device senses the low Hz, to begin with.

Yes, but not all that difficult. There are several solutions available to the hobbyist. From the lowly Rat Shack electret to 15-inch subwoofer drivers. All can produce different but usable results.

My most recent inspiration: http://www.jclahr.co...iezo/index.html

Beauty, in relative simplicity. Very good!

[Old Guy]

Robot, on Feb 27 2010, 09:41 AM, said:

Beauty, in relative simplicity. Very good!

Ah... If you like simplicity (I certainly do!), consider a pair of speakers (the bigger the better) in an isobaric configuration for an LF microphone. I've got one on the bench connected to an old laptop running Spectrogram and just dumping ASCII files once every 24. I'm still waiting for the USGS to release their data, but I'm pretty sure it picked up the quake in Chile.

[Robot]

Old Guy, on Mar 2 2010, 11:31 AM, said:

Robot, on Feb 27 2010, 09:41 AM, said:

Beauty, in relative simplicity. Very good!

Ah... If you like simplicity (I certainly do!), consider a pair of speakers (the bigger the better) in an isobaric configuration for an LF microphone. I've got one on the bench connected to an old laptop running Spectrogram and just dumping ASCII files once every 24. I'm still waiting for the USGS to release their data, but I'm pretty sure it picked up the quake in Chile.

Very Cool! I liked your linked sites. Do you have a site of your own?

My favorite speaker, was the mechanically powered one Mythbusters created inside a Mercedes. The whole interior of the car was the "speaker", the driveshaft mechanicall moved the speaker. Pressure blew the sunroof out.

[Old Guy]

Robot, on Mar 3 2010, 04:16 AM, said:

Very Cool! I liked your linked sites. Do you have a site of your own?

My favorite speaker, was the mechanically powered one Mythbusters created inside a Mercedes. The whole interior of the car was the "speaker", the driveshaft mechanicall moved the speaker. Pressure blew the sunroof out.

I do. Or rather she does. If I could figure out where to update my profile I'd add it. It's all art and miniatures, though. Google Minimotion.

I missed that Mythbusters! I'll have to do search for it...

[Robot]

Old Guy, on Mar 3 2010, 04:51 PM, said:

Robot, on Mar 3 2010, 04:16 AM, said:

Very Cool! I liked your linked sites. Do you have a site of your own?

My favorite speaker, was the mechanically powered one Mythbusters created inside a Mercedes. The whole interior of the car was the "speaker", the driveshaft mechanicall moved the speaker. Pressure blew the sunroof out.

I do. Or rather she does. If I could figure out where to update my profile I'd add it. It's all art and miniatures, though. Google Minimotion.

I missed that Mythbusters! I'll have to do search for it...

I like the website, years ago I lived in Colorado Springs, Colorado. Michael Garman Galleries is located there. "Magic Town" is a miniature "city block", you can walk through. You can look in the windows at the miniature occupants and furnishings.

What I liked about "Magic Town" was that the Occupants and Furnishings for a given room, CHANGED. For instance, look in the diner window one minute, it's empty, look again and it has occupants.

This neat (2) views for one room is done with a one way mirror separating the room at a 45 degree angle, backligt one side and see one view, backlight the other and see a completely "different" looking room throught the same window in the same "dollhouse".

My first experience with "One Way Mirrors" was at a Carnival as a kid, I saw a beautiful woman turn into a Gorilla before my very eyes, very neat trick when done properly.

Here is a link to Michael Garmans Magic Town:

http://www.michaelga...com/magic_town/

[RodoBabbins]

That's why I love this place, all of this information to learn. I will definitly have to check out these sites. I'm interested in the building of the detection devices, of course I have a lot to learn about circuits and like. Will have to try out the Radio Shack method since it's probably cheaper and easier for a first timer.

[Robot]

RodoBabbins, on Mar 4 2010, 09:57 AM, said:

That's why I love this place, all of this information to learn. I will definitly have to check out these sites. I'm interested in the building of the detection devices, of course I have a lot to learn about circuits and like. Will have to try out the Radio Shack method since it's probably cheaper and easier for a first timer.

Most of us are here to help. Feel free to ask any questions you have, or PM if you like.

[Old Guy]

Robot, on Mar 4 2010, 04:53 AM, said:

This neat (2) views for one room is done with a one way mirror separating the room at a 45 degree angle, backligt one side and see one view, backlight the other and see a completely "different" looking room throught the same window in the same "dollhouse".

That's an old theatrical trick called Pepper's Ghost. That's how we do the "magic" armoires.
http://en.wikipedia....per's_ghost.

[Old Guy]

Robot, on Mar 4 2010, 07:58 AM, said:

Most of us are here to help. Feel free to ask any questions you have, or PM if you like.

Not me. I'm here to add chaos to the confusion.

[Robot]

Old Guy, on Mar 4 2010, 10:20 AM, said:

Robot, on Mar 4 2010, 04:53 AM, said:

This neat (2) views for one room is done with a one way mirror separating the room at a 45 degree angle, backligt one side and see one view, backlight the other and see a completely "different" looking room throught the same window in the same "dollhouse".

That's an old theatrical trick called Pepper's Ghost. That's how we do the "magic" armoires.
http://en.wikipedia....per's_ghost.

Very Good! Glad to see you are making use of the application. Neat stuff, thanks for the link.

[Old Guy]

RodoBabbins, on Mar 4 2010, 07:57 AM, said:

That's why I love this place, all of this information to learn. I will definitly have to check out these sites. I'm interested in the building of the detection devices, of course I have a lot to learn about circuits and like. Will have to try out the Radio Shack method since it's probably cheaper and easier for a first timer.

As it happens, there's a myriad of microphone elements that actually have good low-frequency characteristics. Some of them have been identified as suitable candidates for use in infrasonic work: http://www.ees.nmt.e...phone_list.html

There's also a dizzying array of FREE(!) software for analyzing captured sounds:
http://www.ultimaser...ltimaSound.html
http://www.trueaudio.com/rta_abt1.htm
http://www.softpedia...shot-94748.html
http://www.sdrham.com/spectran.html
http://pensa.fr/freqresplot/indexe.htm
http://www.weaksignals.com/

Ad nauseum. My problem is finding time to evaluate everything I want to try!

The trick(s) here are to match a sound card (if your built-in rolls off too early), with a mike that has sufficient low-end response, and an analysis package wich will scale the display down to say... 0 to 20Hz. Can be done on the cheap but it ain't the most elegant solutions.

Steve in NM

[CaveRat2]

The weak link in any infrasound app with a computer is the sound card. Most roll off dramatically below about 10 Hz. This would limit their usefulness in this portion of the spectrum. There are cards that use direct coupled (DC) amplifiers but those are rare. If you happen to have one it will work well provided your microphone or sensor also goes to those low frequencies.