Generate Stable 50Hz From a Crystal

Hello everyone and welcome to this instructable! This tutorial is about generating some stable square wave signals by using the very popular and reliable quartz crystal. These crystals are the same crystals deployed in most analog clocks to keep track of time, which proves its stability as compared to other timing methods.

This short article is going to mention the way in which I was able to generate a stable 50 Hertz square wave signal along with a 1Khz signal by using a crystal of a certain resonance frequency and some popular counter and Logic ICs.

So without any further delay, let's get started!

For this project the parts are really simple and can be easily available in your local hardware store. The main part of this project is of course the crystal because that is the frequency determining factor for this whole circuit.

These are the parts that I have used for this build:

1. 4.096 Mhz crystal
2. IC 4060 Binary counter/ divider
3. IC 7490 binary and decade counter
4. 22 pf ceramic capacitor
5. Breadboard
6. Connecting wires

For measuring the frequency you will need an oscilloscope.

This project deploys 2 ICs to first, use the natural frequency of the crystal to convert it into square wave and then using the binary counter/divider to reduce the frequency to the desired one and then second, further divide it by the decade counter to get out target 50Hz square wave frequency.

The first IC is the 4060 which is a binary divider which can work with external timing components ( R C timing components) which determines the operating frequency of the circuit. Alternatively as this IC has a build in Schmitt trigger so it can also handle the input coming directly from a crystal. The two 22pf capacitors are used to maintain the crystal oscillation. As you can see from the image that each pin of the 4060 has a certain dividing factor by which it will divide the original crystal frequency. At pin 1 of the IC we have a dividing factor of 4096 and using a 4.096Mhz crystal can give us an exact frequency of 1Khz at this particular pin. Similarly we have a dividing factor of 8192 at pin 2 which means we can get a 500Hz signal from pin 2 as well which will be utilized to get out 50Hz eventually.

The second IC is the 7490 binary and decade counter. This is a unique IC which deploys divide by 5 and divide by 2 feature and we can even combine both this sections to get a divide by 10 configuration. This is exactly what we have done here. The 500 Hz from pin 2 of 4060 is first fed to the divide by 5 circuit and then to the divide by 3 to eventually get our stable 50Hz signal.

One point to note here is that we must first divide by 5 and then by 2, though the reverse is also possible and will give you 50Hz signal but the duty cycle will not be 50 percent. If you are not concerned about duty cycle, then any configuration of the 7490 IC would be fine for you.

There may be different methods to get a divide by 10 also but I found this to be the easiest one.

I have attached the links to each of the IC's data sheet if you want to read more:

Link to IC4060 datasheet: https://www.ti.com/lit/ds/symlink/cd4060b.pdf
Link to IC7490 datasheet: https://www.jameco.com/Jameco/Products/ProdDS/50690.pdf

This is the complete schematic of the project. Be sure to check the maximum permissible operating voltage of each IC from the datasheet. In my case both are 5V tolerant so I used a 7805 voltage regulator to power the system from a 9V battery

With the concepts out of the way, now all that was remaining was to make the circuit and test it out. The images show my breadboard setup. Make sure to keep your connections neat and tidy to avoid wrong connections which can end up frying your IC.

To check the output I have used a cheap but useful mini oscilloscope.

As you can see I am able to get both my desired frequencies from this circuit. It works just as expected!

You can experiment with different crystals to get your desired frequency using this concept.

I hope this small instructable was useful for you. Please share your feedback in the comments below and do not forget to watch the video in the beginning to get the complete understanding and while you are there consider subscribing to my channel :)

I will see you in the one one!