# synthesizer project

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#### AnDr3w

##### New Member
Hi. I'm pretty new to the world of analog synths and electric instrument building in general. I am trying to build a synthesizer based off of the 74HC14 IC. If I am correct this IC has 6 inputs. I am trying to figure out which combination of capacitors and resistors will create the frequency for each note. I will be using 2 IC's to create the 12 notes. I now middle C is 261.63 Hz. I don't know what formula will be able to help me solve this I'm not even sure if I am going about this the right way but I thought this would be a good place to find out

##### Well-Known Member
While it is possible to cause each one of those inverters to oscillate, we usually design a simple oscillator with two of these inverters. This means you can get three notes out of each IC.

You should also know that the output of these oscillators will be rectangular in wave shape, not sinusoidal, so they will be rich with harmonics and may sound unpleasant.

#### AnDr3w

##### New Member
thanks for the help with the IC's. I did know that the output will be rectangular. As for the frequency of the note how would I go about setting that as opposed to using a potentiometer?

#### AnDr3w

##### New Member
hey thanks for the help. I do have one question. T= the oscillation period. what exactly is that? is that just 1 second? I'm confused sorry haha I'm a noob when it comes to this but we all start there right?

#### drbenne

##### New Member
T is the time it takes for one period of a wave to complete. If you take the reciprocal of a frequency you will get its period (T) and vice versa

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#### AnDr3w

##### New Member
thanks for the help everyone. I will be trying this very soon

#### audioguru

##### Well-Known Member
If the load resistance is not low then only one inverter makes the variable frequency rectangular wave generator (buzzer).
Then you have a long way to go to change the rectangular (buzzer) sound into a triangle, sawtooth or sine wave. Then you need a circuit to change the attack and decay so it is not simply full blast on then nothing off like a car horn.

#### kpatz

##### New Member
You're going to need trimpots, as you aren't likely to hit the correct RC values with fixed components to get each note correct.

Those oscillators are going to drift out of tune though. How many are you planning on using? Some synths and electronic organs use "divide-down" architecture, where there's oscillators for each note in the top octave, and then dividers (flip flops) are used to generate the lower octaves.

#### AnDr3w

##### New Member
I would like to have something like 12 or 24 key depending on the cost. I figured I wouldn't be able to achieve exact frequency's with fixed components and was thinking along that line. the IC I am using has 6 inputs so either 2 or 4 of those. I will have to look into the "divide-down" architecture. thanks for all the help. I need to get a breadboard and all the parts and really just start experimenting with it all

#### audioguru

##### Well-Known Member
In "the good old days" there were top octave generators that accurately produced an entire octave of frequencies. They are not made anymore but some sharks hoarded some and will sell you one for a small fortune. Then digital divider ICs made the other octaves.

There were "transconductance" amplifier ICs that were voltage-controlled amplifiers. One might still be made today.

#### Mr RB

##### Well-Known Member
I've done a few designs with PICs, generating the note frequencies with the PIC timers (which are xtal locked of course).

It's not that hard to read the keyboard with the PIC, then generate polyphony (a few notes) at the same time.

If you google for "DIY synth" there is a bit of a resurgence in home synth making, and a lot of people now are using PICs to act as VCO, VCF, VCA modules etc to replace old synth chips that are no longer available.

#### audioguru

##### Well-Known Member
Some people say that a synth is too perfect in its pitches. Real musical instruments all have slightly different frequencies that make additions and subtractions in the levels at random periods.

#### Raju C

##### New Member
sir can you help me to do the synthesizer programming of CMX7031 pls

#### audioguru

##### Well-Known Member
sir can you help me to do the synthesizer programming of CMX7031 pls
Please do not call western people a SIR. Only children from INDIA call people a SIR. A SIR is sombody who was knighted by the queen Of England. I have never met the queen of England.

I don't know what is a CMX7031.

#### Raju C

##### New Member
ok.. CMX7031 is a radio processor it is having inbuilt synthesizer .. so through GUI i enter frequency and send the value of 16bit .. but CMX calculates its own N value for synthesizer like
EX:if i send 3E85h value it calculates two values as one for TX and one for RX
4285 and 440F
actually it does the padding of bits operation ..

#### Mr RB

##### Well-Known Member
Someone's got the grumpy's today... Did your knighthood get passed over again?

Actually I think "Sir" is nice. It's a standard of good manners for children to call a male adult, and for students and young adults to call a person in any position of authority; teacher, judge, police officer etc.

From what i've seen of the Indian edicational system it's very "British" with children being taught to respect their superiors. A great system. Or you can have the Amercian system where high school students don't even know that they HAVE superiors... Then you have 1/4 of high-school graduates can't even pass the national literacy test.

#### audioguru

##### Well-Known Member
My American neighbours do not have any education. Literacy?????

There are not many Indian and Australian people here, SIR.

#### Raju C

##### New Member
I actually mentioned sir to radioron and audioguru replied and doesn't want me to call him sir its his wish but it doesn't mean that we leave calling sir to others .. I might have answered him but it is not that big issue to discuss so i dint bother about that much ..so i want my question of CMX7031 to be answered

#### audioguru

##### Well-Known Member
I actually mentioned sir to radioron and audioguru replied and doesn't want me to call him sir its his wish but it doesn't mean that we leave calling sir to others .. I might have answered him but it is not that big issue to discuss so i dint bother about that much ..so i want my question of CMX7031 to be answered
Oh. Radioron is a knight? He was knighted by the queen of England?

Does it hurt a lot to be a knight???

Some guys in this world call other guys their MATE. But my wife is my MATE.
Birds, bees and all animals have the opposite sex as their MATE.
Those other odd guys have another guy as their MATE.
WEIRD! Maybe they should be called a SIR. Not me.

This world has people who are completely different.

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