Need to design an IR Receive amplification circuit for digital processing

[truclacicr]

Re: Need to design an IR Receive amplification circuit for digital processing

Use a single supply, rail to rail comparator, eg MAX941.

https://cdn.badcaps-static.com/pdfs/...acaf490fe5.pdf

Use a resistive potential divider for the 4V set point (see figure 6 on page 9).

[budm]

Re: Need to design an IR Receive amplification circuit for digital processing

We don't know how OP is measuring the pulse voltages. With a multimeter it's averaged and doesn't tell you much.
OP is also thinking a weak signal means less signal swing which is not the case with modules because they have built-in amplifiers, AGC, clamps and a comparator to give the same output signal weak or strong IR signal.

A photo-transistor will give a weak or strong signal though, so this seems part of the confusion or maybe even what OP is using for a receiver. We will never know.

Yep, we will never know. OP asks questions but refuse to provide the info + lack of basic understanding of the electronics and devices.

[redwire]

Re: Need to design an IR Receive amplification circuit for digital processing

We don't know how OP is measuring the pulse voltages. With a multimeter it's averaged and doesn't tell you much.
OP is also thinking a weak signal means less signal swing which is not the case with modules because they have built-in amplifiers, AGC, clamps and a comparator to give the same output signal weak or strong IR signal.

A photo-transistor will give a weak or strong signal though, so this seems part of the confusion or maybe even what OP is using for a receiver. We will never know.

[budm]

Re: Need to design an IR Receive amplification circuit for digital processing

You still refuse to give us the spec of the IR receiver you are using and also the waveform, simple request.

[EasyGoing1]

Re: Need to design an IR Receive amplification circuit for digital processing

you need a schmitt-trigger like a 74hc14, not a transistor.

but that's not going to help because your receiver output is already digital - you need a better and more sensitive one.

I'm not convinced that it won't help, because when a weak signal reaches the receiver, it sends a higher voltage to the Arduino ... and as I stated when I started this post ... if that pin gets between 2.2 and 2.5 volts, it will waffle the interrupt trigger, so if I can set 4 volts as an absolute that will guarantee sinking that pin to ground, then I will have completely overridden the effects that a weak signal has on this ir sensor and I will have given the Arduino a solid 0 even if the IR receiver gets a weak signal ... (because a strong signal causes the IR receiver to go to about 1 volt while a weak signal can make it only drop to 2-ish volts) ... so then with this idea, all that signal needs to do is drop that voltage by only 1 volt and I'm in business ... make sense?

[stj]

Re: Need to design an IR Receive amplification circuit for digital processing

I'm not sure how any of this information is relevant to my original question, which was... how do I design a circuit such that when a voltage hitting the base of a transistor is at 5V, the transistor is off, but when that voltage goes to 4 volts or lower, I need the transistor to be on as hard as it can be?

you need a schmitt-trigger like a 74hc14, not a transistor.

but that's not going to help because your reciever output is already digital - you need a better and more sensitive one.

[budm]

Re: Need to design an IR Receive amplification circuit for digital processing

Starting a new thread is not going help or learning anything from it.
https://www.badcaps.net/forum/showth...235#post935235

https://www.badcaps.net/forum/attach...3&d=1578415503
So how low does the output of the IR receiver go down to?
Does the IR receiver has built-in pull-up on the IR output pin?

[eccerr0r]

Re: Need to design an IR Receive amplification circuit for digital processing

I'm not sure how any of this information is relevant to my original question, which was... how do I design a circuit such that when a voltage hitting the base of a transistor is at 5V, the transistor is off, but when that voltage goes to 4 volts or lower, I need the transistor to be on as hard as it can be?

I'm not asking anyone to help me solve my core issue, because I believe if I can create a circuit that would sink that Arduino pin to ground as soon as that source voltage goes to 4 volts or lower, my problem would be solved, and I really want to test my theory.

If my actual question is not clear enough, please let me know what needs clarification.

The problem is that we don't have characterization of the IR receiver output we can use. Its output impedance could be so high that even using a common emitter transistor doesn't have enough gain to drive the transistor.

Hence I have to assume the worst that you need to use those op amp comparators with really high input impedance that will amplify anything, and you get to choose whatever threshold you want. These amplifiers are slow, but should be fast enough for IR use.

And even if this amplifies the digital output, that weak signal has already been filtered out and no amount of amplification can be used to recover the signal. The amplification you seek would need to occur within the module, and as an IC I'm not sure what you can do with it.

[budm]

Re: Need to design an IR Receive amplification circuit for digital processing

You are not provide the info we requested.

[EasyGoing1]

Re: Need to design an IR Receive amplification circuit for digital processing

I think I'm just going to start a new post on this topic and leave out the discussion which seems to be throwing everyone off for some reason.

[budm]

Re: Need to design an IR Receive amplification circuit for digital processing

Yes, I do and I have.

Show us the scope (set to DC) wave form of that IR output.
So where is the U1 SPEC?

[EasyGoing1]

Re: Need to design an IR Receive amplification circuit for digital processing

"I am still wondering if the original setup is actually working before at all. Lots of details are still missing.

As I stated in my original post, the project works FINE until the batteries in the remote go from 1.5 volts per battery to 1.4 volts per battery, which can take about 7 to 8 months... but I want to attempt to extend that time by implementing the idea that I have which was also included in my original post.

[EasyGoing1]

Re: Need to design an IR Receive amplification circuit for digital processing

Again, none of this makes sense until we know what that U1 IR receiver's "OUT" characteristics are like - what is its manufacturer and model?

Usually if it requires power, it already has amplification and the output is a digital signal. Amplifying it further doesn't make sense. You may need to simply choose another U1 or build your own with your own phototransistor or photodiode. But there's not enough information to tell.

As a blind answer without knowing what U1's output is like, you might as well use a LM339 op amp and set the other input to the exact threshold you want, and it will drop the output down fast when the output level goes below what you set... however this solution doesn't answer the real problem.

I'm not sure how any of this information is relevant to my original question, which was... how do I design a circuit such that when a voltage hitting the base of a transistor is at 5V, the transistor is off, but when that voltage goes to 4 volts or lower, I need the transistor to be on as hard as it can be?

I'm not asking anyone to help me solve my core issue, because I believe if I can create a circuit that would sink that Arduino pin to ground as soon as that source voltage goes to 4 volts or lower, my problem would be solved, and I really want to test my theory.

If my actual question is not clear enough, please let me know what needs clarification.

[EasyGoing1]

Re: Need to design an IR Receive amplification circuit for digital processing

I wonder if OP even looks at the signals with scope.

Yes, I do and I have.

[budm]

Re: Need to design an IR Receive amplification circuit for digital processing

I wonder if OP even looks at the signals with scope.

[redwire]

Re: Need to design an IR Receive amplification circuit for digital processing

I don't think your problem is with the logic levels.
For best performance from those IR modules, add an RC filter to its VCC feed something like 100 ohms and 10-47uF. The Arduino's noise on 5V can really make a module do poorly for range (or a weak signal from IR remote with low batteries). Even 25mV of noise on Vcc causes problems.

If the module is next to noisy signals it will also do poorly. In commercial products, a grounded shield made from mesh window screen goes around the module.
Otherwise, CFL or LED lights can cause interference as well.

[stj]

Re: Need to design an IR Receive amplification circuit for digital processing

maybe this will help make things clearer.

[budm]

Re: Need to design an IR Receive amplification circuit for digital processing

"but it's just a standard remote controller that puts out infra red light signals in a square wave pulse that the Arduino can analyze and use according to the code created and uploaded into the arduino." It sound s like op is using the Arduino to do the decoding function.
I am still wondering if the original setup is actually working before at all.
Lots of details are still missing.

[eccerr0r]

Re: Need to design an IR Receive amplification circuit for digital processing

Again, none of this makes sense until we know what that U1 IR receiver's "OUT" characteristics are like - what is its manufacturer and model?

Usually if it requires power, it already has amplification and the output is a digital signal. Amplifying it further doesn't make sense. You may need to simply choose another U1 or build your own with your own phototransistor or photodiode. But there's not enough information to tell.

As a blind answer without knowing what U1's output is like, you might as well use a LM339 op amp and set the other input to the exact threshold you want, and it will drop the output down fast when the output level goes below what you set... however this solution doesn't answer the real problem.

[EasyGoing1]

Re: Need to design an IR Receive amplification circuit for digital processing

What is the spec of the U1 IR receiver?
So you want IC A1 input to be active low then, so PNP transistor will be used so when IR receiver U1 output goes low it will turn on the PNP transistor (Collector is ground, Emitter to A1 input)

So it would look something like this then?