Buidling this circuit Drawdio (again)

• k_squared
In summary, Building this circuit can be difficult. You might need to check the resistor value and the frequency.
k_squared
Buidling this circuit "Drawdio" (again)

I THOUGHT I had it together, but the only sound it makes is when I break/ make the connection continuously. I did notice that on the 10K resistor, there is little (>1ohm) resistance on it, which I suppose is fine, because its on a transistor in there?

Other than having someone more competent inspect the circuit, what mistakes might one readily make which would cause that?

Oh and thanks for any help.

The battery voltage on that circuit is shown incorrectly. It should be shown with the negative end grounded and the positive end going to pins 4 and 8 of the chip. You might need a new chip if the voltage has been wrong.

Pin 3 should not go directly to the bases of the transistors. Try at least 4.7 K there.

The frequency should be about 3.4 KHz which is probably too high. If you put a 0.0047 uF capacitor at C instead of the 680 pF, the frequency would be about 500 Hz.

Here is a calculator for working out the frequency:
http://freespace.virgin.net/matt.waite/resource/handy/pinouts/555/index.htm

Check the 10 K resistor again. It really should measure 10 K, out of circuit.

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To be safe I should mention this: I am using a 1.5 volt with a 551. Do I still need a resistor?

Being the cautious type, I like to build very simple circuits to test components. I have a soldered 555 tester, and a bread boarded tone generator to test my speaker. Hence, I would like to build a tester for the 551. However, when I looked up the behaviour of R/C circuits, wikipidia threw differential equations at me which I know nothing of. I was going to use that calculator to design one; does the voltage have any effect on the fill rate?

I found a data sheet for the 551:

The equations in it look like the ones for the 555. So, the 555 calculator will probably give you ballpark figures for the frequency.

Yes, you need a resistor. At least 1 K.
As a general rule, you never put semiconductor junctions directly across a power supply, even in series and even 1.5 volts.

The first step would be to get it working on some frequency and then modify the values for whatever frequency you want.

If your 555 tester has a socket for the chip, you could put this 551 in it to see if it is still working. They work with a supply from 1 to 15 volts and the pin connections are the same.

HaHa! It was working the whole time - I was just gripping the wires on the ends so lightly the output was nill!

Oh and thanks for the advice. That really helps to understand the 555, in my mind. Besides, I learned how to test transistors in the process.

1. How do I build the Drawdio circuit?

To build the Drawdio circuit, you will need a 555 timer IC, a resistor, a capacitor, a potentiometer, a speaker, a battery, and some wires. First, connect the 555 timer IC to the breadboard. Then, connect the resistor and capacitor to the appropriate pins of the IC. Next, connect the potentiometer and speaker to the circuit. Finally, connect the battery to power the circuit. For a more detailed guide, you can refer to the Drawdio circuit diagram.

2. What is the purpose of the 555 timer in the Drawdio circuit?

The 555 timer is a versatile integrated circuit that is commonly used in electronic circuits. In the Drawdio circuit, it is used as an astable oscillator, which produces a square wave signal that is then sent to the speaker to create sound.

3. Can I use different components for the Drawdio circuit?

Yes, you can use different components for the Drawdio circuit as long as they have similar characteristics and ratings. For example, you can use a different value resistor or capacitor, but make sure they have similar resistance and capacitance values. You can also experiment with different types of speakers to create different sounds.

4. How does the Drawdio circuit work?

The Drawdio circuit works by using the 555 timer to generate a square wave signal, which is then sent to the speaker. The potentiometer controls the frequency of the square wave, which in turn changes the pitch of the sound. When the circuit is connected to a pencil, the graphite acts as a variable resistor, changing the frequency of the signal and creating different sounds as the pencil moves across a piece of paper.

5. What are some troubleshooting tips for the Drawdio circuit?

If your Drawdio circuit is not working properly, here are some troubleshooting tips you can try:

• Check all connections and make sure they are secure.
• Make sure you are using the correct components and they are connected in the right places.
• Check the battery to make sure it has enough power.
• Check the potentiometer to make sure it is functioning properly.
If the circuit still does not work, you may need to double-check the circuit diagram and your connections, or try using different components.

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