[SOLVED] trouble with sensor?????

[Elimathew]

hey guyz im using TSOP 1838 as my sensor for my line follower ive connectecd the sensor as given in the datasheet but it is not working at all.even if the light is incident on it or not the output remains constant(4.86V)

 

[FvM]

Did you notice, that the sensor only works with 38 kHz modulated light?

 

[kak111]

TSOP 1838 --frequency 38kHz

The TSOP18.. – series are miniaturized receivers for
infrared remote control systems. PIN diode and
preamplifier are assembled on lead frame, the epoxy
package is designed as IR filter.
The demodulated output signal can directly be
decoded by a microprocessor. The main benefit is the
reliable function even in disturbed ambient and the
protection against uncontrolled output pulses.

This sensor needs IR-light input 38kHz +/- 5%

Continous light and other frequencies are filtered out.

You need for ex. 555 ic oscillator for driving IR-led.

http://www.datasheetcatalog.org/datasheets/134/301155_DS.pdf

KAK

 

[Elimathew]

no i didnt know that, which phototransistor then i should use according to you with LED as transmitter

 

[FvM]

You need for ex. 555 ic oscillator for driving IR-led.

According to the TSOP1838 specification, this won't work reliably. Continuous modulation is suppressed by the automatic gain control. You'll need a second modulation.

 

[kak111]

Here is IR-Led transmitter with 555-ic for TSOP 1838 --frequency 38kHz

Look----TV REMOTE CONTROL JAMMER
50 - 555 Circuits

Opto transistor receivers...
- these are sensitive to continous light too.
_ any phototransistor is useful ( needed switching frequency is small )

**broken link removed**

IR detector circuit

google finds more........

 

[Elimathew]

thank you for the reply,i also wanted to ask that as im doing line following robot , when the light falls on the black line the output of the sensor should be low but its always giving me 4.86V

---------- Post added at 15:47 ---------- Previous post was at 15:39 ----------

 

[kak111]

Line Follower Robot Scanner Schematic

The LED emit invisible infrared light on the track and the phototransistor works as a receiver.
Usually, black colored surface reflects less light than white surface and more current will flow
through the phototransistor when it is above a white surface.


Line Following Robot Sensor

Phototransistor must be biased so that it has resolution high enough to sense black & white.

 

[FvM]

Here is IR-Led transmitter with 555-ic for TSOP 1838 --frequency 38kHz

I guess, there's a difference between a RC jammer and reliable operation of the sensor. If you want to operate a similar device, I really suggest to notice the datasheet.

 

[kak111]

im doing line following robot , when the light falls on the black line

Line follower sensor must be able to give analog output. ( ie. react to different gray levels )
IR-controller receiver TSOP 183x is not designed for this.
Reflective opto-sensor CNY70 is right choice or use discrete components (Led & optotansistor)

KAK

 

[Elimathew]

thanks kak i will try CNY70