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Resistors and?

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A CD4047 IC has an RC oscillator and a divide-by-two digital divider giving a perfect 50:50 duty-cycle. A second divided output is inverted from the other output.
Then the CD4047 IC will replace your CD4069 oscillator and the CD4013 divider.
The timing resistor for the CD4047 oscillator should be at least 10k ohms.
 
A CD4047 IC has an RC oscillator and a divide-by-two digital divider giving a perfect 50:50 duty-cycle. A second divided output is inverted from the other output.
Then the CD4047 IC will replace your CD4069 oscillator and the CD4013 divider.
The timing resistor for the CD4047 oscillator should be at least 10k ohms.

Thanks,

4047 is a monostable chip I think? Can it provide a good oscillation at 80khz?

I am not sure of its circuitry as a stable oscillator and divider, Hope google can help!

In the real circuit I have several pins for 4066 and 4069 (and probably for 4047 for the next configuration) which are not used? I think I have to ground all of them, right? Or I must just ground inputs? What about TL072?

Ron,
In your modification the input has a wire that goes to ground. I used a single power supply for the circuit finally and grounded the non inverting pin of TL072 via two 1k resistors. I did so for the input too (but with two 470 ohm resistors). but I guess I can get more stable result when I connect that input pin into real ground of my single ended power supply. What is your idea please?
 
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I found The circuitry of 4047 as a stable oscillator. It is a stable/monostable chip.
It seems to be a nice chip for many tasks. Thanks for recommending it.


I will purchase it and modify my circuit by it today .

P.s. This thread is the best one I have started recently, essentially I designed this circuit to learn the principles of digital designing (specially CMOS ones) and modulation simultaneously, now I think I am reaching that aim by your helps. Thanks a lot for all your advices.
 
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I found The circuitry of 4047 as a stable oscillator. It is a stable/monostable chip.
It seems to be a nice chip for many tasks. Thanks for recommending it.
Here is a CD4047 IC used as the 50Hz, 60Hz clock in a power inverter.
 

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Hi guys

Thank you very much for all your helps and advices on my design and taking time to modify it (especially to you Ron)
It does work just fine without any problem right now. I was able to overcome the quark problem by modifying the circuit by 4047 (thanks to you audioguru).

Now I want to modify the current circuit to a 'SSB' with carrier or 'VSB' with carrier. Can someone direct me to a good solution to do so?
Because this circuit uses logical chips can I use a simple way to reach to 'ssb' or 'vsb'?

Thanks for any other help.
 
I used an MC1496 balanced modulator/demodulator IC to make a SSB suppressed carrier audio scrambler for a wireless boardroom tele-conferencing system.
The transmitted sound was completely un-intellegible but the de-scrambled sound was perfect.
 
audioguru,

I am not sure if I understood you by 'de-scrambled'?!

Which way did you use to create the ssb signal? The phasing way or the filtering way?

Anyway I am decided to do so and because I have used the logical components till now so hope someone here is able to give me a point simpler than the common ways of doing a such system.
 
I filtered out the unwanted sideband with a switched-capacitor lowpass filter IC.
The transmitted signal had high frequencies sounding like low frequencies and low feequencies sounding like high frequencies. Voices sounded like they were talking in a strange foreign language.

I used another MC1496 IC to reinsert the carrier to "de-scramble" the SSB suppressed carrier signal.
 
What about using a MF10?

Maybe the reason you had a bad sound was having a SSB without the carrier for the transmitter?

I guess working with a chip like 4066 is much simpler than a working with MC1496 and the output result of 4066 would be much more better than an old MC1496 too.
 
An MF10 is an older dual second-order filter. I used an improved LMF40 4th-order Butterworth lowpass filter IC that is no longer made.

Since my audio scrambling circuit used single-sideband with a suppressed carrier then it was completely scrambled. Adding the correct carrier frequency at the correct amplitude to the scrambled audio resulted in perfect audio.

I don't know why the circuit in this thread is making amplitude modulation and why it is using CD4066 transmission gates.
 
I hope you guys help me to get the response of the gate floating question..?
Do I need to ground all unused inputs of 4066 and 4047?
What about their outputs? If so why we have to do so?

Ron,
I faced a problem and hope you guys are able to help me to solve it.
When I put my MP3 Player at 3 kHz (Since I have no signal generator, so I have saved a 3 kHz sine wave audio in my MP3 player and use it as my modulating signal) and connect it to the modulator and tune the volume to have some carrier I have to tune it again when I use an electrets mic instead of the mp3 player. How can I solve the problem to have a fixed carrier for when put one of two?
Hope you guys understand my mean!
 
In general any cmos IC pins that are unused need to be terminated somehow, is this covered in the PDF anywhere?
 
You must never leave a CMOS input floating. It must be connected to the proper voltage for the circuit to function. Ground the unused inputs of the CD4066. Connect the CD4047 like I posted it.
 
Thanks,
Are you talking about EVERY input pin or just ones that part of them is used? I mean consider a cmos chip with for gates, if I want to use just 1 gate do I need to ground other gates that I did not use their inputs and outputs? Do we need to ground the realted ouput pins too?

Can someone help me with my question about connecteing an electret mic...

Thanks a lot
 
EVERY input pin on a Cmos logic circuit must be connected to the correct logic voltage.
Some gates need an unused input connected to the supply voltage and other gates need an unused input connected to ground to function.
NEVER connect an output to the supply voltage nor to ground or the Cmos IC might burn out.

You have a very simple and strange modulator circuit. You did not post the preamp circuit for your electret mic so we don't know what is its output level.
 
EVERY input pin on a Cmos logic circuit must be connected to the correct logic voltage.
Some gates need an unused input connected to the supply voltage and other gates need an unused input connected to ground to function.
NEVER connect an output to the supply voltage nor to ground or the Cmos IC might burn out.

You have a very simple and strange modulator circuit. You did not post the preamp circuit for your electret mic so we don't know what is its output level.

Ok thanks audioguru,
What about 4066 with every pin acts as input/output?

Why the modulator circuit is strange?

Well I have not used any other preamp for the circuit, just connected the electret mic through a capaciotor to the original opamp which I am currently using (the modifiction of Ron), I did not forgot to put abiasing resistor to the electret mic.

Can I use anothere opamp as the electret mic amplifier and feed both the mic and the mp3 player via a switch?

I can use a dynamic mic for the current circuit but do not know how to connect it to Ron's modifiction so that nothing changes.
I am gathering some info about mics and their circuitry.

Ron what is your opinion please?
 
Since a CD4066 analog gate has an output that could be its input then to safely unuse it then turn it on by connecting its control pin to the positive supply and ground one of its input/output pins.

The carrier frequency of your AM modulator has a square wave. Most carriers are a sinewave.

A microphone has a very low signal level so it needs to be amplified by a preamp.
 
Since a CD4066 analog gate has an output that could be its input then to safely unuse it then turn it on by connecting its control pin to the positive supply and ground one of its input/output pins.

The carrier frequency of your AM modulator has a square wave. Most carriers are a sinewave.

A microphone has a very low signal level so it needs to be amplified by a preamp.


Good idea about 4066, Thanks for it,

I think it is no matter using each sine or square waves as carrier.

As I told before I have a op-amp in the circuit right now (please take a look at Ron modifiction) But I am not able to handle it by both the electret or dynamic mic and the mp3 player without changing the volume for each ( I want the volume to be fixed for that signals).

Can I use another op-amp and put the mp3 player and mic to it (they do not be connected to it simultaneity but I do not like to change the volume every time).

As a dynamic mic has a low impedance can I connect it to the current circuit (connecting it to the input of the op-amp).

Can someone direct me if evey device which have an input for a mic and for another device like mp3 player uses just one jack for these both devices or just one jack?

Sorry If I am not able to be more clear, my english lang is very bad
 
Your AM modulator has a 80kHz square-wave for its carrier. Then it produces interference at all the odd-harmonics:
240kHz, 400kHz and higher. The odd harmonics at 560kHz, 720kHz, 880kHz, 1040kHz, etc will cause interference on the AM Broadcast band.

I told you that the microphone needs to have a preamp circuit to increase its output level from 5mV it is now up to 150mV which is the level from the MP3 player. Then the gain of the preamp must be about 150/5= 30.
 
I am getting confuced about handelling the current circuit with an electeret or dynamic (600 ohms)!

I do not matter if it interfaces to AM Broadcast band because it is just for learning, besides the output is very small in power.

Do you ever have seen any device which is able to work with just one input jack as the mic jack and the input jack for another thing like an mp3 player or so? Can I make a such circuit or I need a switch to do so?

Thanks
 
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