Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Mistake in IR tranceiver circuit

Status
Not open for further replies.

MPYC

Junior Member level 3
Joined
Apr 29, 2011
Messages
28
Helped
2
Reputation
4
Reaction score
2
Trophy points
1,283
Activity points
1,501
Hi dears.
I designed a circuit for sending and receiving infrared signal. its range is about 1 meter but it have to pass 2 7 millimeter wholes. I used common 5mm IR emitter and receiver diodes. VCC2 and VCC1 are 12V for ground1.
IC's part number is NE555 and its frequency set on 7kHz. 555 just produce a simple continuous pulse. pick voltage on LED is about 1.35V and the voltage that drop out over R18 is about 9.75V. LED is 5mm IR once.
if other parameter is necessary please tell me.
may you please check my my circuit and see if I have weakness in circuit?
distance of sensors(emitter and receiver) and boards are about 2 meters. I attached image of sensors.
I don't have any problem with 555 and emitter diode because when I check it with phone`s camera I see that it work.. but in emitter part after some days or months system can not sense any signal.at this time, I touch terminals(I attached its image too) or I open wires and close them again, problem solved.
or coupler capacitor C16 brake and pass DC signal.
any idea?
thanks all.
 

Audioguru

Advanced Member level 5
Joined
Jan 19, 2008
Messages
9,211
Helped
2,128
Reputation
4,250
Reaction score
1,955
Trophy points
1,393
Location
Toronto area of Canada
Activity points
57,863
The part number and polarity of the "collector" diode are not shown. Is it forward biased or reverse biased?
The values for the 555 timing parts C16, R19 and R20 are also not shown.

Opamp U2A is inverting with a low input resistance of 10k that loads down the output level from the collector photo diode. The opamp should be non-inverting so its input resistance can be higher than 10 times the value of R21.
 
  • Like
Reactions: MPYC

    MPYC

    Points: 2
    Helpful Answer Positive Rating

MPYC

Junior Member level 3
Joined
Apr 29, 2011
Messages
28
Helped
2
Reputation
4
Reaction score
2
Trophy points
1,283
Activity points
1,501
unfortunately I can't find any part number for photo diode because it don't have part number in its body but I bias it in reverse mode. do you know about maximum invert voltage of this kind of diode?
I think you need value of C16, R19 and R20 for frequency, it's about 7Khz.
your idea about using op-amp in non-invert mode is good but do you see any problem in this design?(my signal power is good enough)
 

Vbase

Full Member level 6
Joined
Apr 7, 2015
Messages
367
Helped
74
Reputation
148
Reaction score
72
Trophy points
28
Activity points
1,997
In the part of the receiver circuit that you show us nothing can cause the problem of latching that you have. The problem is likely with the other part of the receiver (not in the picture), an opamp or a cmos gate laches up and when you remove the power it resets.
 

MPYC

Junior Member level 3
Joined
Apr 29, 2011
Messages
28
Helped
2
Reputation
4
Reaction score
2
Trophy points
1,283
Activity points
1,501
In the part of the receiver circuit that you show us nothing can cause the problem of latching that you have. The problem is likely with the other part of the receiver (not in the picture), an opamp or a cmos gate laches up and when you remove the power it resets.

signal pass the last op-amp and after a little process it go to uC.
even after a restart the problem still remain. just after replugging the sensors wire problem solved.
I use very thin wire for signal. maybe it result the problem.
does weak current of sensors led the problem?

dear why op-amp latch up?
what about broke coupler capacitor?
 

Vbase

Full Member level 6
Joined
Apr 7, 2015
Messages
367
Helped
74
Reputation
148
Reaction score
72
Trophy points
28
Activity points
1,997
In some opamp when the input goes outside the supply voltage the opamp stops working, it's called latch up.
If you suspect a cap breaking the best way is to change it for another type.
 

Audioguru

Advanced Member level 5
Joined
Jan 19, 2008
Messages
9,211
Helped
2,128
Reputation
4,250
Reaction score
1,955
Trophy points
1,393
Location
Toronto area of Canada
Activity points
57,863
I asked for part values for the 555 timing parts because there are many values that produce 7kHz but some values should not be used with an ordinary 555 but are fine with a Cmos 555. Maybe the resistor values are too high for your 555.
Your circuit is missing important supply bypass capacitors that keep the ICs from oscillating at a very high frequency. Maybe your circuit breaks into oscillation after a while.
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top