analyze circuit consist of transistors and OpAmps

Status
Not open for further replies.
B

babaiem1378

Newbie level 4
Joined
Oct 13, 2023
Messages
7
Helped
0
Reputation
0
Reaction score
0
Trophy points
1
Visit site
Activity points
57
Hi everyone.
I have a complicated circuit consist of a 4051G multiplexer which my circuit is connected to third pin, the circuit have three transistors and 2 OpAmps and some resistors and capacitor and its schematic attached to this post; if someone help me to analyze this circuit please tell me what does this circuit exactly do.
thanks for reading and helping.

 
Last edited by a moderator:

Solution
The range issue is basically path loss but could be optical or electrical interference. If the Tx currents can be increased safely, then it is possible to increase the range, but that might cause thermal issues.

Does it happen on more than 1 unit?

It appears this design might use burst carriers in the typical IR carrier band around 30 kHz or like IRDA1 pulses looking at the RC time constant ratios. It does not use AGC and tries to detect the carrier amplitude using a fixed-gain using 2 diodes as a voltage-doubler after a chain of fixed-gain RC signal conditioners. The filter looks somewhat like an RIAA pre-emphasis to boost HF more than LF.

I would expect black filters on the detectors to block daylight and FL flicker interference...
Sort by date Sort by votes
Hi,

the first bjt at the input makes no sense.
The Diode-capacitor -to GND at the OPAMP outputs make no sense.

So either drawn incorrectly .. or the circuit makes not much sense.

Klaus
 

Upvote 0 Downvote
The first part is a transistor blower-upper circuit. No resistors on base, emitter or collector. The rest of the transistors, i don’t know. then there’s a leaky integrator connected to another leaky integrator. Need a better drawing.
 

Upvote 0 Downvote
FvM said:
Some details are probably copied incorrectly, but wen can guess the overall function.
What's the application?
Click to expand...
In the safe light curtain application, I have two boards facing each other, one of which has 32 IR receivers and the other has 32 IR transmitters, and each board has 4 mux4051s, one transmitter from the board at a given time. The first and the opposite receiver on the second board are selected by two attiny 24 microcontrollers that are located on each board and are synchronous with each other. When the distance between the receiver and the transmitter is more than half a meter, the input signal to the microcontroller from the mux 4051 in the receiver board is weakened and the microcontroller is not able to detect the signal. What is your solution to this problem?
 

Upvote 0 Downvote
KlausST said:
Hi,

the first bjt at the input makes no sense.
The Diode-capacitor -to GND at the OPAMP outputs make no sense.

So either drawn incorrectly .. or the circuit makes not much sense.

Klaus
Click to expand...
In the safe light curtain application, I have two boards facing each other, one of which has 32 IR receivers and the other has 32 IR transmitters, and each board has 4 mux4051s, one transmitter from the board at a given time. The first and the opposite receiver on the second board are selected by two attiny 24 microcontrollers that are located on each board and are synchronous with each other. When the distance between the receiver and the transmitter is more than half a meter, the input signal to the microcontroller from the mux 4051 in the receiver board is weakened and the microcontroller is not able to detect the signal. What is your solution to this problem?
 

Upvote 0 Downvote
Audioguru said:
The scribbles and faint crooked wires are very hard to read.
Click to expand...
In the safe light curtain application, I have two boards facing each other, one of which has 32 IR receivers and the other has 32 IR transmitters, and each board has 4 mux4051s, one transmitter from the board at a given time. The first and the opposite receiver on the second board are selected by two attiny 24 microcontrollers that are located on each board and are synchronous with each other. When the distance between the receiver and the transmitter is more than half a meter, the input signal to the microcontroller from the mux 4051 in the receiver board is weakened and the microcontroller is not able to detect the signal. What is your solution to this problem?
 

Upvote 0 Downvote
In the safe light curtain application, I have two boards facing each other, one of which has 32 IR receivers and the other has 32 IR transmitters, and each board has 4 mux4051s, one transmitter from the board at a given time. The first and the opposite receiver on the second board are selected by two attiny 24 microcontrollers that are located on each board and are synchronous with each other. When the distance between the receiver and the transmitter is more than half a meter, the input signal to the microcontroller from the mux 4051 in the receiver board is weakened and the microcontroller is not able to detect the signal. What is your solution to this problem?
barry said:
The first part is a transistor blower-upper circuit. No resistors on base, emitter or collector. The rest of the transistors, i don’t know. then there’s a leaky integrator connected to another leaky integrator. Need a better drawing.
Click to expand...
In the safe light curtain application, I have two boards facing each other, one of which has 32 IR receivers and the other has 32 IR transmitters, and each board has 4 mux4051s, one transmitter from the board at a given time. The first and the opposite receiver on the second board are selected by two attiny 24 microcontrollers that are located on each board and are synchronous with each other. When the distance between the receiver and the transmitter is more than half a meter, the input signal to the microcontroller from the mux 4051 in the receiver board is weakened and the microcontroller is not able to detect the signal. What is your solution to this problem?
 

Upvote 0 Downvote
Um, amplify the signal? Move the receiver closer to the transmitter? Use higher power transmitter?

But this has absolutely nothing to do with your original question.
 

Upvote 0 Downvote
The range issue is basically path loss but could be optical or electrical interference. If the Tx currents can be increased safely, then it is possible to increase the range, but that might cause thermal issues.

Does it happen on more than 1 unit?

It appears this design might use burst carriers in the typical IR carrier band around 30 kHz or like IRDA1 pulses looking at the RC time constant ratios. It does not use AGC and tries to detect the carrier amplitude using a fixed-gain using 2 diodes as a voltage-doubler after a chain of fixed-gain RC signal conditioners. The filter looks somewhat like an RIAA pre-emphasis to boost HF more than LF.

I would expect black filters on the detectors to block daylight and FL flicker interference.

In order to disregard interference, one needs to perform an isolated test from stray light or EMI.


I had once designed an 8-channel IR light curtain to perform flawlessly across a 1m lane on the profile of a shopping cart to identify if goods were in the bottom basket. I was also able to detect a resistor wire crossing any of the optical paths in isolation using 5 mm standard 10 deg LEDs @ 100 mA.

You might think I needed a laser, but not here with a narrow 2 mm aperture and recessed Tx & Rx optical components.

In order to make it work without co-channel crosstalk and reach 1m reliably using low-power LED emitters, I needed to do the following;

1. Each emitter pulse was driven sequentially and each Irda1 Rx was received synchronously. The missing pulses indicated a blocked "air-pipe" across the lane. Then the lower rail of a shopping cart with the depressed nose matched "key" positions of the IR Tx-Rx pairs, then the cart was detected.
2. Rather than discrete filters and amplifier detectors, IRDA1 detects from Sharp/Vishay were used. This was key to my design as the IRDA1 detectors are reliable high gain and high SNR detectors.
3. The TDM method of pulse train detection made it easier to MUX the signals digitally on a PICs 8 IO ports. 4. The firmware could then detect 2 other IR ports just above the shopping cart bottom rail for any shopping item (like a case of beer) or canned goods someone might have forgotten at the cashier.

Suggestions.
1. Get the supplier to fix the problem
2. Get an expert to fix the problem.
 

Upvote 0 Downvote
Solution
In the safe light curtain application, I have two boards facing each other, one of which has 32 IR receivers and the other has 32 IR transmitters, and each board has 4 mux4051s, one transmitter from the board at a given time. The first and the opposite receiver on the second board are selected by two attiny 24 microcontrollers that are located on each board and are synchronous with each other. When the distance between the receiver and the transmitter is more than half a meter, the input signal to the microcontroller from the mux 4051 in the receiver board is weakened and the microcontroller is not able to detect the signal. What is your solution to this problem?
in the circuit of safety light curtain, there are 2 npn bjt transistors and 1 pnp bjt transistor and 2 op amp that configured as inverted input, and I want you to solve and analyze this circuit,
thanks for reading and helping me so much.

 

Upvote 0 Downvote
D.A.(Tony)Stewart said:
What other details , specs, test results can you offer to describe the problem and expectations?
Got a link to the product specs?

There are 3 requirements not given;
TX power,
Path Loss,
Rx threshold.

Which ones do you think are failing?
Click to expand...
Hi sir, thanks for reading my problem
I only want to know how this circuit work and what is the reason of placing each element in circuit schematic.
can you interpret this circuit?
 

Upvote 0 Downvote
babaiem1378 said:
Hi sir, thanks for reading my problem
I only want to know how this circuit work and what is the reason of placing each element in circuit schematic.
can you interpret this circuit?
Click to expand...
Yes, but that won't help you solve the path length problem. nor will it explain why someone decided to do it this way if you do not understand my comments so far.
 

Upvote 0 Downvote
Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…