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LM567 vs LM567CN

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chemelec said:
Ti is Different.

Ti Formula Multiplies the C1 R1 result by the 1.1
Mine Divides it by the 1.1.


This (chemelec):
upload_2015-10-25_15-6-35.png


And this (TI):
upload_2015-10-25_15-8-41.png


are identical.
1
___ = b/a

(a/b)


John

Edit: Maybe we are looking at different datasheets. This is from the one posted by Kubeek:
Capture.PNG
 
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I Used a .1 uf Cap but with Various Resistance Values and got Correct Frequencies on my Frequency Counter.

If you use a .01 Cap and a 5.8K resistor, you will come Close to your 19Khz.
Remember that Just because a Cap is Marked .01, Does Not mean it is that Exact Value.
Possibly use a 5K6 resistor in series with a 500 Ohm trimpot to Get the Exact Frequency of 19Khz.

Note the Supply Voltage MUST be Regulated at 5 Volts.
Or the Frequency will Change with Supply voltage changes.

Thanks for that. I use L7805 to stabilise the voltage at 5V. A 9V battery is used to power that.
The input signal is coming from a USB soundcard.

Here are the other components I used:
C3 (PIN1) = 0.02μF
C2 (PIN2) = 0.007μF
C4 (PIN3 - input signal) = 0.01μF
PIN4 - Supply Voltage (from L7805) = 5.07V
R1 (PIN5) = 5K8 (to be precise, multimeter shows 5831Ω)
C1 (PIN6) = 0.01μF (multimeter: 97.6 nF here)
PIN7 is GND
PIN8 - LED for testing. There is a 47Ω resistor between the cathode of the LED and the cathode of the 9V battery.

The circuit responds mainly to frequencies between about 16kHz and 19.5kHz, but also to those around 6-8kHz. Also, it's not very stable - a small change in the input signal volume (coming from the soundcard) affects the bandwidth greatly, but the F0 seems to fluctuate as well. I feel there may be a flaw in the circuit somewhere.

Here's what it actually looks like:
2.png 3.png 4.png 5.png 6.png
 
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The Input Signal Must be kept Below 0.2 Volts.
47 Ohms is LOW.
470 or 680 ohms would be more suitable with a 9 Volt Supply

Here is the formula, Re-Written:
It Make More sense to Calculate for R1, if you know C1 and the Frequency you want.
LM567-Formula.png
 
This 567 Posting are in good Timing for me.
Been Many Years since I last used this IC, (Probably 1980's) but I presently need to do a Design for my Towns Reservoir Supply.

I have already have a monitor that detects the depth of water in Inches, in the reservoir.
From this, I need to make a Comparator circuit to tell if the water level goes Too High or Too Low.
Too High Overflows the 100,000 Gallon Reservoir.
Too Low and we could run out of Water.

The output of this comparator needs to turn on a transmitter and transmit a Specific Tone.
(This Specific Frequency Should Eliminate False Triggering)
(Motorola Walki-Talki)

In our Towns Office will be a Receiver with a Tone Decoder for that Frequency.

If Activated, the receiver will Trigger a Telephone Dialer on a land based phone and send out a Record Message to certain people in town, telling them their is a Problem with the Water Supply. (It can Sequentially Dial up to 9 Numbers.)

Unfortunately we are Not in an Area that we can use a Cell Phone Dialer.
They have Limited Use in NORTH AMERICA.
 
The detection bandwith can be reduced by choosing bigger C2. With C2=1uF bandwith is about 600Hz.
Recommended C3 > 2×C2
Decoupling capacitor ~ 1uF between 5V-gnd near IC is needed.
 
Uljabaan, This Circuit will Limit your Input voltage to less than the 0.2 Volts.

Ok, this sounds promising. Can you point me to some sort of online documentation, so I could understand why/how this circuit works?
I would like to understand if it normalises the signal (so it will lower the levels below 200mV as well) or crops anything above 200mV or does something else entirely?
 
Ok, this sounds promising. Can you point me to some sort of online documentation, so I could understand why/how this circuit works?
I would like to understand if it normalises the signal (so it will lower the levels below 200mV as well) or crops anything above 200mV or does something else entirely?

Your High Input signal goes in through the 1K Resistor.
Than the two diodes, Clip this voltage down to about 0.7 volts.
Lastly the 1K and 220 ohm resistors Divides this .7 volts down to about 0.15 Volts. (150 mV)

Added Note:
The LM567 is recommended to have a Square Wave input Signal.
Even if your signal is a Sine wave, this will also make it a Square wave.
 
Actually Vin can be > 0.2V rms, see TI datasheet.
It only has a minor effect to bandwidth calculation.
 
On My Bench Tests, When going Too High on the input Signal Voltage, The Output does not go fully Low when outside of the set frequency.
According to my Data Sheet, the Lowest Detectable input is about 20 mV, But usually recommended to be between 100 & 200 mV.
 
Before I implement the circuit suggested by chemelec https://www.electro-tech-online.com/threads/lm567-vs-lm567cn.146094/page-2#post-1236496 I would like to check what the input signal voltage actually is. As I have mentioned, the signal is coming from a USB soundcard. How do I do that?
I have set my multimeter to the AC mode and the reading fluctuates around 0.022 V - the volume doesn't really affect the reading much, and it never exceeds 0.023, which is way below 200mV. I am playing a sine wave of 440Hz for this test. Am I measuring the voltage correctly? If so - it doesn't really make sense to apply the limiting circuit, does it?

EDIT:
If I measure that correctly and the Vrms is indeed 0.02V AND the lowest detectable input is indeed 0.02V as well, would that explain the stability issues I am having? Is it worth adding an amplifier to the signal?

Thanks for all the advice, much appreciated.
 
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Yes your signal is a Bit Low.
You Might be best to add an amplifier and the Diode Circuit.

On My Test Circuit, Putting in a Sine Wave, It Triggers at Two different Frequencies.
It is set for 1100 Hz, But also triggers at 350 Hz.
I Tested this with Both the Square and Sine wave Signals between 0 and 20 KHz.

It Only Triggers at 1100 With the Square wave.

Your Choice to do what you want.
 
The volume control of the sound card should affect the signal level. Is the signal taken from the headphone output?
The level 20mV is very low.
Something is wrong. Try to measure the signal level without LM567
 
I am playing a sine wave of 440Hz for this test.

What Values of Capacitors are you using for C2 and C3 on the 567 chip?

At 440 Hz, C2 should be a 1uF and C3 Should be a 2.2uF Cap.
 
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For what its worth:

Given the variation(s) in value for most common R and C components,, the stability of your Vcc, etc., attempting to mathematically pre-determine the actual 567 internal oscillator frequency generated is, essentially, impossible.

Look into this software: https://www.nch.com.au/tonegen/index.html.You can download a free trial copy.

Having played with the 567 a good deal, the Linear Tone Sweep function of the above software allowed me to find the exact (as close as possible) "trip frequency" for my particular 567 circuit and it's RC network. Using the formula from the datasheet really only gave me a gross ball park value for what any two components might yield.

Once I had found that trip point and to assure a consistently reliable output (since I couldn't control temperature variations), I feed the final 567 circuit a swept frequency (50 to 75Hz either side of the ≈19kHz I was using). I used a sine wave as well; a square wave had far too many harmonics and forced an occasional false trip.

I never needed any front end filters.
 
I don't need that Software, I have a Frequency Generator, an Oscilloscope and a Frequency Counter.
But it is probably useful for persons that don't have these items.

Capacitors are Rarely an Exact Value, Neither are Resistors.
So it is better to use a Resistor, Slightly lower than required in series with a Suitable Lower Value Trim-pot, Than adjust to the Exact Frequency.

I was just playing with the Idea of Changing the 567's Bandwidth as a function of input Voltage.
This circuit works good, if you have a Signal voltage Greater than about 0.8 Volts.
LM567-Bandwidth.png
 
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