Simple electronic piano

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Found a simple circuit for obtaining beep sound with different frequencies, that's the say different notes.

Here is the circuit;
View attachment 61365

However the problem is that, I couldn't obtain the necessary resistor value to get specific frequencies.

By changing R2, I would be able to do that. However with Multisim application I couldn't obtain the frequency with given resistor value.

Frequencies I want to get are those;

View attachment 61366

Can anyone manage to do that. Shouldn't be hard but I'm not good at using that application probably.

 

[jpanhalt]

If you are absolutely sure of the resistances you need (I wouldn't trust the simulation that much), then you can buy 1% resistors and parallel a pair for each note. Here is a calculator from TI for calculating individual resistors in a parallel pair, but the site is temporarily down: **broken link removed**

However, I would buy a bunch of trimmer resistors (one for each note) and use them either individually or in series with some near-correct fixed resistors, such as 100 Ω, 220 Ω, 333 Ω, etc. plus a 100 Ω trimmer. That way, you can tune the piano too.

John

 

[zoom]

If you are absolutely sure of the resistances you need (I wouldn't trust the simulation that much), then you can buy 1% resistors and parallel a pair for each note. Here is a calculator from TI for calculating individual resistors in a parallel pair, but the site is temporarily down: **broken link removed**

However, I would buy a bunch of trimmer resistors (one for each note) and use them either individually or in series with some near-correct fixed resistors, such as 100 Ω, 220 Ω, 333 Ω, etc. plus a 100 Ω trimmer. That way, you can tune the piano too.

John

Thank you John for your advice. However, the problem itself is the ambiguous values of resistors, that's why I want to use a simulator to get the approximately value of the resistor which gives me the frequency I want.
Tuning the piano with a trimmer resistor is also a solution but it's a huge chore.

There must be a way of doing that through simulators.

 

[jpanhalt]

Try LT Spice (free, Linear Technology). I think you can use any value and any tolerance you want for your components. I have no experience with Multisim. Remember, your capacitors will not be very accurate. I don't think you can rely on the simulation.

You could do a 2 or 3 point calibration curve (i.e., actual vs. simulated), then calculate the values more closely, but I still think you will need to tune it.

John