ashrau

I'm trying to build this project, that will play the first line of the tune "Happy birthday to you". I want to use only 6 tones (frequencies) to play the tune.

The basic idea that I tried implementing is that, the 4093 IC produces pulses of a specific frequency (determined by C5 and R1). The frequency is supposed to be adjustable, so I'm using a potentiometer as R1.

The output from the 4093 pulse goes to the 4017 decade counter (5-stage johnson), the outputs of which are connected to a 555 timer. As each output of the decade counter goes high, the 555 timer (operating in astable mode), is to produce an output, the frequency of which will vary with the resistances (potentiometers) connected to the decade counter outputs. Therefore, by varying the potentiometers at the 4017 outputs, the frequency of the output (tones) at the 555 timer should change. And setting the resistances in sequence to produce specific frequencies should produce the tune. The hex inverter is used to reset the 555 timer, after giving gaps after the last tone played, and then the 9th output resets the 4017 to start the tune over again.

PROBLEMS:

So far, here's the trouble im having. The 4093 schmidt trigger nand gate isn't giving a pulse of consistent frequency. It seems to be varying between two frequencies. This appears to get fixed when i remove the ground connection from the Vss pin. Should I just remove the ground? Is that good for practical purposes when i make this circuit on the breadboard?

I dont seem to be getting any output at the 4017 counter and the 555 timer. I do get an output when i remove the ground from the Vss pin of the 4017 timer. However, its not the right output. THe frequencies don't change at the 555 timer as they should. Right now I have an 8 ohm resistor simulating the presence of an 8 ohm speaker. I have the potentiometers at the decade counter set to produce the following tones at the 555 timer output, giving the tune for the 1st line of "Happy birthday to you" (potentiometers should be set at 100%, as opposed to 50% as shown in diagram). I need potentiometers because i want to be able to change the tunes produced by
changing the output frequencies of the 555 timer.

Also, i'm not getting a square wave at the speaker. Its a very distored wave. Could be some speaker loading issue ?

Can anyone please guide me on what i'm doing wrong, and how I need to modify this circuit to get the results i want?

Here are the frequencies i'm using for the tune:

392 392 440 392 523 494 (Hz)
G G A G C1 B
"ha ppy birth day to you"

Any help will be greatly appreciated. Thanks !!

Oz

Attached Images

tune_player.jpg (156.5 KB, 12 views)

Attached Files

tune_player.pdf (51.5 KB, 4 views)

k7elp60

On problem I see, you need decoupling capacitors for you entire circuit. More specifically one from pin 8 of the 555 to ground as close to the IC as possible. The circuit shown will not produce a 50% duty cycle squarewave.
The load on pin 3 may be two low in resistance.

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kchriste

What simulator are you using? You'll definitely need to connect Vss to ground on all chips in the real world. Also, unused inputs on CMOS ICs need to be tied to either Vss or Vdd. You cannot let them float. You don't need D7. You can't tie O6 & O7 on the 4017 together like that because they are both outputs. You need to run all the CMOS ICs from the same voltage. You can't run one on 5V, another on 9V like that. They'll all work on the 9V just fine. Try something like this:

Attached Images

tune_player.jpg (122.8 KB, 11 views)

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ashrau

Hi kchriste,

Thanks for the input. I'm using MultiSim ver. 10. I tried making the modifications, but it doesnt seem to help. I still don't get any output at the 4017 decade counter, or the 555 timer. The pulse frequency from the 4093 schmidt trigger is still variable, however i noticed that it seems to get very close to constant when I configure the pot to 100% of its resistance value, i.e 100k ohms. I'm not sure why that is though. The signal from the 4093 just doesn't seem to be triggering any response from the 4017. Is it possible that the incoming frequency is too high for the 4017 ? Any thoughts would be appreciated. Thanks

kchriste

Unlikely. Not if you are using the values listed in the diagram.

Repost a schematic of the circuit as you have it set up now. I don't have MultiSim, but maybe someone else here does, so you could post the MultiSim file as well.

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