IR receiver

[shiva garg1]

hello every body i am working on ir transmitter based on 555 timer and ir reciver based on vishay TSOP1738 receiver modeule..transmitter is working fine giving 65%duty cycle pulses of ir radiation at 38 khz ..my problem is reciver whose output and associated problem is shown in attachement... plz help me

scanned.pdf

 

[audioguru2]

Does your TSOP1738 have the recommended 4.7uF supply bypass capacitor?

 

[waferstar]

Dear,
I think that is because that you may miss a  bypass capacitor 10uF between the output and the GND.
And if you have any other problems,you can paste your circuit here,and that is easy for us to solve this problems for you.


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Frank
Shanghai Wafer Microelectronics Co.,Ltd
www.waferstar.com
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[shiva garg1]

although author has recommend bypass capacitor but i did not use it because i am using supply from company made power supply and author has directly taken output without the use of capacitor between output and ground...will these capacitors solve my problem....and i will try to paste my circuit...

 

[shiva garg1]

yes...my circuit is working . i can transfer 2500bps by ir and thanks to audio guru and waferstar because the pinpointed the right problem when i used the bypass capacitor circuit start working.......now let me explain my circuit then i will ask anpther question .
i genrated 38khz ouput from 555 timer and gave this output to one i/p oin of 'AND ' gate and to second input pin i gave serial data then the output was given to base of transistor which drives the IR led connected in its collector leg. and on receiver side there is simple IR receiver module....the +5v supply to transistor ,reciver and "AND" gate is coming from the same point.NOw this circuit works when there is by pass capacitor in reciver why this is so????is my transistor genrating hamonics in supply line or something else???plz tell me ...i am looking forward to audioguru and waferstar for the answer because without this my project will not be complete

 

[audioguru2]

All electronic circuits work better with a supply bypass capacitor. It is a current resevoir and a very low impedance at high frequencies and keeps amplifying circuits from oscillating and from bouncing around.

 

[shiva garg1]

sorry,audioguru i did nor get u..can u tell me in detail what u mean

 

[audioguru2]

A supply bypass capacitor:
1) It is a current resevoir. It supplies very high momentary current to the circuit when needed. Very useful with a battery that has its internal resistance rising as it runs down.
2) It is a low impedance at high frequencies to stop amplifiers from oscillating and to keep oscillators from stopping due to feedback through the supply.
3) It holds the supply voltage steady, so it doesn't bounce around by load current changes.