Author Topic: using 555 timer  (Read 4419 times)

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Offline lavishgarg28Topic starter

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using 555 timer
« on: December 25, 2008, 10:55:41 PM »
hello every one...
can any one tell me what are the adequate values of resisters and capacitor connected to 555 timer to generate 38KHz frequency?
i need it to generate 38Khz ir for tsop....

more over i used 1k for first resister and a pot for second one with 10 nf capicter..
i can detect the signal aprroximately at 1.8k value of r2.. but its range is getting variable..
at starting at particular calibration it detect obstacle only at 5 cm and after 2min it starts detecting obstacle at 45cm..  after some time it starts decreasing but at a low pace...

can any one help me what can be the problem?
i am working on it from past few days.  PLEASE HELP

Offline airman00

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Re: using 555 timer
« Reply #1 on: December 26, 2008, 08:51:57 AM »
Check out the Roboduino, Arduino-compatible board!


Link: http://curiousinventor.com/kits/roboduino

www.Narobo.com

Offline Soeren

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Re: using 555 timer
« Reply #2 on: December 27, 2008, 11:28:35 PM »
Hi,

i need it to generate 38Khz ir for tsop....

[...] its range is getting variable..
at starting at particular calibration it detect obstacle only at 5 cm and after 2min it starts detecting obstacle at 45cm..  after some time it starts decreasing but at a low pace...

can any one help me what can be the problem?
First, you need to understand that TSOP (in capital letters) is just the prefix for a range of infrared receiver modules, which has different specs, so you need to be a bit more specific and give us the entire name of the module you are using. The rest of the name will reveal the working frequency and other important data.

Some of the members of the TSOPxxxx family has got ways of dealing with noise (which is just about any signal not being a regular modulated signal):
A quote from a manufacturer:
Quote
"in the presence of a disturbance signal, the sensitivity of the receiver is reduced to insure that no spurious pulses are present at the output.
Some examples of disturbance signals which are suppressed are:
• DC light (e.g. from tungsten bulb or sunlight)
Continuous signals at any frequency
• Strongly or weakly modulated noise from fluorescent lamps with electronic ballasts"
This could be what causes your problems, so an exact module number is needed to see if this is likely.

If your module is one of those, you either have to get another type, or to modulate your signal in a noncontinuous way to counter the error correction, but another module will be the best option.
Some modules work down to 2.7V, other will cease working under 4.5V, so if you are running from a battery, this should be taken into consideration as well.
(I assume you made sure that ambient light could not be the cause of the problem).

Apart from the module number, please attach the schematic of the circuit you are working on (both receiver and transmitter end) as well.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

 


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