Loud speaker output problem based on analog circuit

[v.s.n.kumar]

Hi,
If we give 11001101 continously to a speaker then it generates sound. My question is if I give 00111001 to it then it generates a different sound or not.

 

[FvM]

11001101 or 00111001 are obviously binary numbers rather than analog quantities. The question is useless without telling which kind of decoder or converter is involved between the digital data and the analog circuit.

 

[v.s.n.kumar]

When I press a button in IR remote, the transmiter transmit modulated signal at 38khz. TSOP1337 recieves it.when receiver receives, a sound will generate in a speaker. If I press for long time,the intensity of sound must change. can u give any idea about this circuit by using Op-amps or 555, transistors,etc with out using micro-controllers(only analog electronics).

 

[crutschow]

If you explain what you are tying to do then perhaps we could better understand your question.

 

[Audioguru]

If the remote control generates 11001101 continuously then it makes 11001101110011011100110111001101 etc.
If it generates the different code 00111001 continuously then it makes 00111001001110010011100100111001 etc. which will sound a little different.
Both will produce buzzing sounds. Some people will not hear any difference.
I do not know if your remote control changes the code if it transmits for a long time. The intensity is the loudness of the sound. It does not change.

 

[D.A.(Tony)Stewart]

Most IR remotes support many protocols, each different in some way. But for redundancy the codes are repeated but in a burst. WHen held down , they are cycled on and off.

As far as symmetrical codes. 11001100 repeating, would sound similar to 00110011 because they are only inverted phase but same frequency.

 

[v.s.n.kumar]

I'm trying to design an analog circuit which is based on 555 timer or op-amps only. the main aim of my circuit is when I press a button from IR remote, the IR receiver TSOP1738 receives it. Every button on IR remote has different binary information. if i press 1 then i have to produce sound. if i press 2 then the TSOP1738 receives binary information which is different from previous button binary information. so i have to generate sound at another frequency. then by that sounds we can know that user is pressing different buttons. with using voltage controlled oscillator, based on the different binary information's, i have to generate different sounds with out using micro-controllers, digital electronics, voltage controlled oscillator. so can anybody tell how to generate different frequencies of sounds based on the different binary information's.

 

[D.A.(Tony)Stewart]

Search this site for Class D Audio Amps

 

[Audioguru]

Now you say you want the different binary codes to produce different frequencies.
Then you must use the code to control a variable frequency oscillator. The oscillator can feed an audio amplifier that drives a speaker.
The intensity (loudness) will not change.

You must use a digital circuit to decode the digital code.

 

[chuckey]

If you can afford a serial D to A converter then each set of binary code would produce a different voltage which could sweep the oscillator, as per Audiogurus suggestion. You could try to amplify the the digital stream then pass it through a low pass filter, it would produce a different voltage depending on how many 1s there are.
Frank

 

[Audioguru]

For the first time in my life, I looked at the IR from my cable TV remote control with my digital camera. When a button is held down it sends a code at about 4 times per second. If a digital decoder controlled the frequency of an audio oscillator then you might hear a different pitch beeping for each button on the remote control.

If you simply use the "ones" in the code to produce a voltage that controls the frequency of a VCO then the examples above will vary the frequency such a small amount they will both sound the same.

 

[Borber]

TSOP1738 demodulates IR remote commands from 38kHz AM modulated carrier. It's output is train of square pulses that correspond to code received. Pulse duration can be as short as 2ms and whole block or period interval can be long few tens of ms. Pulses amplitude can be 5V peak and you can use it as audio signal for audio system. Listen to this mess directly by pressing different buttons on remote. All additional analog circuit you need is simple attenuator to adjust 5Vp signal to audio amplifier input.
That's all you can play around with analog.

 

[v.s.n.kumar]

When i connected the output(pin-3) of TSOP1738 to CRO , I saw there is a spike with out pressing remote. how can i reduce that spike in the output voltage of tsop1738. I have connected electrolytic capacitor 4.7 micro Farreds with negative to pin-2(v-in) & positive to pi-1(ground) of tsop1738 according to its datasheet.can anybody tell how to reduce it.

 

[Audioguru]

You have backwards polarity for the 4.7uF capacitor. Pin 2 is positive and pin 1 is negative (ground).
The output at pin 3 is simply the collector of an NPN transistor. It is high (+5V) when there is no 38kHz burst of IR and it is low (0V) when there is no IR or between bursts.
I do not see anything that would cause a voltage spike at the output unless your 5V power supply has voltage spikes.

Is the voltage spike positive or negative?
What voltage does the voltage spike reach to?
When does the voltage spike occur? When the 5V power supply is turned on or is turned off?
Is the voltage spike repeating?

 

[v.s.n.kumar]

It is negative voltage spike. when I turn off or turn on there is no spike. but when i turned on after some time it's come. it is not repeated at regular interval. time gaps between the spikes changes. The output of TSop1738 is 5v, the maximum value of spike is 0v.

 

[Audioguru]

Something is flashing some IR to the TSOP for it to produce an output spike. Or the TSOP is defective.

The 2.1 speaker system that I bought had an intermittent woofer. It came and went when the pcb was wiggled. I saw nothing wrong on the pcb so I assumed the connector to the woofer was bad and I cut it off and soldered the wires directly to the pcb. It fixed it (but for only one week). When the problem came back I looked very closely at the pcb but saw nothing wrong. So I re-soldered every solder joint on the pcb and that really fixed it.

A few minutes ago I fixed an LED chaser circuit. One LED had a high reverse current that caused another LED to light when it should not light. I did not have a spare LED the same for a replacement so I simply connected a Schottky diode in series with the leaky LED.

 

[D.A.(Tony)Stewart]

The IR Rx chip has AGC with high gain so it can pick up noise from supply grounds (if noisy) or stray IR emitters. See if your hand or finger can make it worse or better to locate the source. Although internally shielded , the spike can be radiated, or conducted electrical noise or Very bright fluorescent light.