Forum Menu




 


Log in Problems?
New User? Sign Up!
AVR Freaks Forum Index

Post new topic   Reply to topic
View previous topic Printable version Log in to check your private messages View next topic
Author Message
yyw794
PostPosted: Oct 25, 2007 - 07:22 AM
Wannabe


Joined: Jan 20, 2007
Posts: 69
Location: Mars

in the research , i find the transducer's equation insists a negative resistance. it sounds strange to me, did you heard of that before?

_________________
Our Martians are beginning to learn AVR
 
 View user's profile Send private message Visit poster's website 
Reply with quote Back to top
ka7ehk
PostPosted: Oct 25, 2007 - 07:33 AM
10k+ Postman


Joined: Nov 22, 2002
Posts: 13982
Location: Tangent, OR, USA

Yes, Negative Resistance exists. This is the resistance seen looking into most oscillators when the resonator is removed. You can make negative resistance with an op-amp. Tunnel Diodes also have negative resistance.

I do not understand your phrase
Quote:
the transducer's equation insists a negative resistance
What do you mean by this.

Jim

_________________
Jim Wagner
Oregon Research Electronics, Consulting Div.
Tangent, OR, USA

Fournier RF4d - My dream plane!
 
 View user's profile Send private message  
Reply with quote Back to top
yyw794
PostPosted: Oct 25, 2007 - 08:24 AM
Wannabe


Joined: Jan 20, 2007
Posts: 69
Location: Mars

for the research, someone have calculated that the transducer's (mechanical)characterist can be changed into electrical characterist ,like resistance, capacitance and inductance to be expressed. here, one of the parallel loop is a resistance which shows the negative characterist.
by the way, we will paid the one who can teach us English,the salary is high in Mars, and we can settle with your registered permanent residence problem, and Hamburger freely everyday

_________________
Our Martians are beginning to learn AVR
 
 View user's profile Send private message Visit poster's website 
Reply with quote Back to top
JohanEkdahl
PostPosted: Oct 25, 2007 - 09:10 AM
10k+ Postman


Joined: Mar 27, 2002
Posts: 22027
Location: Lund, Sweden

Quote:

we can settle with your registered permanent residence problem, and Hamburger freely everyday

No offence but ... Intentional or not, this got me LOL!
 
 View user's profile Send private message Visit poster's website 
Reply with quote Back to top
peret
PostPosted: Oct 25, 2007 - 10:42 AM
Raving lunatic


Joined: May 26, 2004
Posts: 2542
Location: Las Vegas, Nevada

There's a very good article on Wikipedia. That's a link to the English version but no doubt the Martian language site also has an article.

"The chances of anything coming from Mars are a million to one", he said.
 
 View user's profile Send private message  
Reply with quote Back to top
yyw794
PostPosted: Oct 25, 2007 - 11:22 AM
Wannabe


Joined: Jan 20, 2007
Posts: 69
Location: Mars

I am the one of a million

_________________
Our Martians are beginning to learn AVR
 
 View user's profile Send private message Visit poster's website 
Reply with quote Back to top
JohanEkdahl
PostPosted: Oct 25, 2007 - 12:43 PM
10k+ Postman


Joined: Mar 27, 2002
Posts: 22027
Location: Lund, Sweden

Quote:

I am the one of a million

Nice to get that verified. We hoped and suspected that it was so, but where not certain... Wink
 
 View user's profile Send private message Visit poster's website 
Reply with quote Back to top
bobgardner
PostPosted: Oct 25, 2007 - 04:23 PM
10k+ Postman


Joined: Sep 04, 2002
Posts: 23978
Location: Orlando Florida

Don't the Martians have a large colony in eastern asia with 2 billion colonists?

_________________
Imagecraft compiler user
 
 View user's profile Send private message Send e-mail Visit poster's website 
Reply with quote Back to top
ka7ehk
PostPosted: Oct 25, 2007 - 05:38 PM
10k+ Postman


Joined: Nov 22, 2002
Posts: 13982
Location: Tangent, OR, USA

Back to the original question:

Strange things do appear when one tries to find electrical analogs to mechanical properties. First, a transducer has very proper electrical characteristics. They can be measured. For a transducer, resistance represents (mostly) the electrical energy that is either converted to heat within the transducer OR is lost through the tranducer conversion mechanism (to outgoing mechanical energy).

It is very possible that the person making this model (that is what it IS) is not interpreting energy flow correctly. If one expects power to flow in one direction and it really flows in the opposite direction, the resistance will appear negative. For example, if you think that the transducer should absorb electrical power, but really creates electrical power (perhaps from mechanical input), it will appear to be a negative resistance device.

Jim

_________________
Jim Wagner
Oregon Research Electronics, Consulting Div.
Tangent, OR, USA

Fournier RF4d - My dream plane!
 
 View user's profile Send private message  
Reply with quote Back to top
ka7ehk
PostPosted: Oct 25, 2007 - 05:54 PM
10k+ Postman


Joined: Nov 22, 2002
Posts: 13982
Location: Tangent, OR, USA

By the way, this is the poster from China who has asked about AC coupling capacitors for oscilloscopes that don't seem to work, about ultrasonic transducers, and has said that he used cracked software because he is a student who cannot offord the real stuff.

I am willing to try to help with genuine technical problems.

Jim

_________________
Jim Wagner
Oregon Research Electronics, Consulting Div.
Tangent, OR, USA

Fournier RF4d - My dream plane!
 
 View user's profile Send private message  
Reply with quote Back to top
barnacle
PostPosted: Oct 25, 2007 - 06:36 PM
Raving lunatic


Joined: Jan 03, 2006
Posts: 4815
Location: Hemel Hemsptead, UK

All a martian needs to know about negative resistance in vacuum field effect devices... http://vintageradio.me.uk/novice/rfpentode.htm

_________________
Neil Barnes
www.nailed-barnacle.co.uk
 
 View user's profile Send private message Send e-mail Visit poster's website 
Reply with quote Back to top
Display posts from previous:     
Jump to:  
All times are GMT + 1 Hour
Post new topic   Reply to topic
View previous topic Printable version Log in to check your private messages View next topic
Powered by PNphpBB2 © 2003-2006 The PNphpBB Group
Credits