Hi everyone, first time user here.

I have a reasonably good background in electronics and electrical circuits and I decided to tackle on this project:

but on a smaller scale first for troubleshooting...

My problem lies in this op-amp setup:

http://imgur.com/rMK8J8I

I will be using the LM324N Op-amp instead of the TLC274 op-amp he uses in his video. They are very similar.
The problem arises with the infra-red reciever/photoresistor signal amplifier.

As seen in the screenshot above he connects the IR's anode to the non-inverting input on the op-amp and a 10M resistor to ground (pull-down?). He then joins the inverting input to the op-amp's output which creates negative feedback if I'm not mistaken?

The things I do not understand:
1. Where are all the resistors to set the op-amp's gain?
2. Why is there a 10M resistor going from the non-inverting input to ground?
3. Should there not be a resistor between the inverting input and op-amp output?

I have include a schematic I have created to aid anyone willing to help me

Schem:
aaaaaalll the way the left

http://imgur.com/IhItULj

 

What are the 33Ω resistors doing there (e.g. R17???)

You better look at the input bias current of a LM324 if you are trying to sub it for a TLC274

 

What are the 33Ω resistors doing there (e.g. R17???)

You better look at the input bias current of a LM324 if you are trying to sub it for a TLC274

Those are current limiting resistors for the photodiodes

 

Those are current limiting resistors for the photodiodes

For the receiving photodiodes?????

 

For the receiving photodiodes?????

SORRY they are PHOTOTRANSISTORS not PHOTODIODES

Yes they aren't ICs, they contain a cathode and anode, Foward voltage drop is 2.2V @ 100 mA, and I'm using 5V to power it with

and the op-amps have an input bias current difference of 20 nA, I don't suppose it will make that much of a difference or what do you think?

 

Yes they aren't ICs, they contain a cathode and anode, Foward voltage drop is 2.2V @ 100 mA, and I'm using 5V to power it with

They are being used as detectors; not emitters. They are supposed to be unpowered.

 

They are being used as detectors; not emitters. They are supposed to be unpowered.

Sorry I edited my previous post... they are photoTRANSISTORS not photoDIODES

 

Hello,

What is the part number of the photoTRANSISTORS?
Have a look in their datasheet to get more info.

Bertus

 

Hello,

What is the part number of the photoTRANSISTORS?
Have a look in their datasheet to get more info.

Bertus

http://www.fort777.co.za/images/Datasheets/LIR132.pdf

 

Sorry I edited my previous post... they are photoTRANSISTORS not photoDIODES

The opamp schematic on Imgur shows a two-terminal photo-diode used as a detector with a 10meg load resistor. That is why the opamp needs to have very low input bias current.

btw- I hate having to go off site to see your pictures. Post them here instead of a external site.

 

http://www.fort777.co.za/images/Datasheets/LIR132.pdf

That is a photo emitter. You are using it as a photo detector (no external bias current needed)

 

That is a photo emitter. You are using it as a photo detector (no external bias current needed)

Well on their website they specifically name is as a "Infra-red 3mm Receiver/Phototransistor" not photoemitter... In my schematic the photoemitters are to the far left and next to it is the photoreciver/phototransistor and amplification setup.

Their webpage:
http://www.fort777.co.za/index.php?main_page=product_info&cPath=269_456_532_534&products_id=2798

 

The opamp schematic on Imgur shows a two-terminal photo-diode used as a detector with a 10meg load resistor. That is why the opamp needs to have very low input bias current.

btw- I hate having to go off site to see your pictures. Post them here instead of a external site.

Sorry first time poster... Will do in the future! Thanks

 

Well on their website they specifically name is as a "Infra-red 3mm Receiver/Phototransistor" not photoemitter... In my schematic the photoemitters are to the far left and next to it is the photoreciver/phototransistor and amplification setup...

So who do you believe?
The guy that made the product and wrote it's data sheet, or some kid that works for a store that made a web page?

 

Who do you believe?
The guy that made the product and wrote it's data sheet, or some kid that works for a store that made a web page?

Maybe they linked the incorrect datasheet to the product?

 

Hello,

I had a look at the website and this seems to be the receiver:
http://www.fort777.co.za/index.php?main_page=product_info&cPath=269_456_532_534&products_id=6076

Bertus

 

Hello,

I had a look at the website and this seems to be the receiver:
http://www.fort777.co.za/index.php?main_page=product_info&cPath=269_456_532_534&products_id=6076

Bertus

That is the matching receiver for the LIR 151, I used the LIR 131 and it's matching receiver which is the LIR132

 

Now that you have figured out that the LIR132 is a reciever, do you still think you need the 33Ω resistor?
Do you still have questions about the opamp?

Here is the relevant data for the receiver:

 

The video in post #1 is one of the worst demonstrations of patience and tenacity I have ever seen. To clarify, I mean, this guy has the patience of Job (pronounced "Jobe") but his high-speed editing work make this look like an afternoon project.

He is really a perfectionist and clearly understands his project and I am sure he will not have a bad connection in the 600 or more solder joints he will make - hundreds of wires to strip and hundreds of Components to place and glue. I didn't even have the patience to watch to the end of the video but, whoever starts this project will have a major investment in components and a firm understanding of the time commitment to complete this project.

I imagine this could be like one of those hooked rug projects from the 1970s. Everyone saw how cool they looked in the craft store but there were few ever completed. I found my mother's 1/4-done rug when we packed up her house several years ago. Very tedious.

 

Now that you have figured out that the LIR132 is a reciever, do you still think you need the 33Ω resistor?
Do you still have questions about the opamp?

Here is the relevant data for the receiver:

View attachment 77500

I was just worried that it would draw too much current? Now knowing that is is a receiver, is my wiring still correct?

and in regard to the op-amp... What EXACTLY is the 10M load resistor for? I thought the input bias current wouldn't need a current limiting resistor?