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farzan
11-16-2004, 11:57 AM
hi everybody,
last month for an exhibition in our college i did my first bot which can sense any obstacles and can turn its path. for detecting obstacles i constructed a proximity sensor with ir txr and rxr(tsop1738)

i designed the txr with 555 astable for 38khz.but practically i got only around 25khz then i modified it putting a pot instead of 'Ra' and measured the frequency as 38khz but the theoretical value was aroun 50khz what would be probably wrong.plz help

bye

vikas
11-16-2004, 02:16 PM
Hi

As most of the components are not standard .. thae cap / resitor ... there is a diffrence in the actual and theoretical value . I had also did something similar for my first bot :) ... But then after poor results and low range i dumped the 555 approach altogether and started using 38 Khz square wave from a uC ( Much easier and a whole lot better ) . i recommend u do the same

Vikas

farzan
11-17-2004, 05:43 AM
hi
how can i increase the sensitivity of ir link current boosters of trnsistors or uln2003 which is better. for a good ir link how much current must be given to led

vikas
11-17-2004, 09:37 AM
As such an IR based link is for small range . But like i said the REciver module u are using is for 38 Khz . So an Transmitter emitteing data modulated at 38Kz can be recived at about 5 - 7 meters . Which is good enogh ( I had done this in m robot to transmit back information ) . For a good IR link i still recommend a good modulation than pumping in more current :) .

Also you can 3 or more IR Leds this also works very efficiently ... Cause u have the risk of buring ur IR Led is the current and voltage are increased beyond a limit .

subot_robot
11-17-2004, 11:03 PM
( I had done this in m robot to transmit back information ) .

Hi vikas,
can u please post the circuit for ir data transfer between robot and computer. if possible plz post a tutorial on how to build it and basics.

ice
11-18-2004, 12:03 PM
hey,
U can use a simple transistor say 2N222
wire the transistor in the foll way

the BASE to ur signal....
the EMITTER to +5 V
and the COLLECTOR to ur ir emitter anode..

done...
that's helluva current Boost :idea: :idea: :idea: :idea: :idea:

ice
//Gerry

Pulkit_gaur
11-18-2004, 10:37 PM
Hi ,

If u need more range for ur link , try laser diodes .. just rip the laser torches which are available for 20 rs./- nowadayz ... make a suitable driver from a BJT like BC547/48 / SL100 for it .

-
:)
Pulkit

ice
11-18-2004, 11:07 PM
Pulkit,


, try laser diodes .. just rip the laser torches which are available for 20 rs./-

They still cost 100+ Rs here...where do u get them for 20 bucks.. 8O

ice

Pulkit_gaur
11-18-2004, 11:19 PM
Hi ,

Well , just try out some roadside shops and a little bargaining ... :)

sumandeep1984
11-24-2004, 07:35 PM
The overall structutre of IR communication involves the following stages:

Transmitter:
MAX232 (Level convertor from serial port level to ttl)
IC 555 38KHz Osc
2n2222A for IR LED driving
Pair of IR LEDS

Reciever:
TSOP1738 IR Reciever / demodulator
uC with UART (Serial Communication Facility)

The individual stages can be easily configured by refering to the respective datasheet test circuits. This scheme can easily handle upto 2.4Kbps data rate.

thamarai kannan
12-17-2004, 10:28 PM
The overall structutre of IR communication involves the following stages:

Transmitter:
MAX232 (Level convertor from serial port level to ttl)
IC 555 38KHz Osc
2n2222A for IR LED driving
Pair of IR LEDS

Reciever:
TSOP1738 IR Reciever / demodulator
uC with UART (Serial Communication Facility)

The individual stages can be easily configured by refering to the respective datasheet test circuits. This scheme can easily handle upto 2.4Kbps data rate.

sumandeep1984
12-19-2004, 09:15 PM
DS232A (By Dallas Semicon) is a functional replacement of MAX232A incase someone finds it difficult to procure.