Instructables

Low cost waveform generator (0 - 20MHz)

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Picture of Low cost  waveform generator (0 - 20MHz)
ABSTRATH
This Project comes from the necessity of getting a wave generator with a bandwidth over 10 Mhz and an harmonic distortion under 1%, all of this with a low cost price.
This document describes a design of a wave generator with a bandwidth over 10MHz , which produce:  sine, triangle, sawtooth, or square (pulse) waveforms with an harmonic distortion under 1%, duty-cycle adjustment, frequency modulation, TTL output and offset voltage. It is also presented the design of a frequency counter.


 
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Step 1: Parts list

Picture of Parts list
LISTA COMPONENTES 2.png
This is the main parts list.
The main part, MAX 038 is a discontinued part, but it still can be bought .

It is attached  an approximate budget.

Step 2: PCB made

Picture of PCB made
TOP JPG (207,5- 52).jpg
Make Ready the PCB for the serigraph.

It is double faced PCB. The chosen process is a chemical one, so the first thing we have to do is the serigraph of the layout with a laser machine, and after the chemical process.



Firstly, we begin  with the layouts in JPG format, due to it is a double faced PCB, we will have to turn over the PCB to do the serigraph by both sides, because we are going to use a laser machine. for this reason the PCB must have exactly  the  same size than the layout or at least one of the sizes,( depending on the direction in which we turn over the PCB).
After cutting  the PCB with the exactly measurements ( it is also possible to adjust the layout at the PCB ) the PCB is painted with black acrylic spray paint. ( it must be painted at least one day before)
The PCB must be placed at the left top corner, ( the 0,0 point of the machine must be exactly at this point) because when we turn over the PCB, it has to be exactly in the same place in order to make the holes coincide.

The layout dimensions are: 207,5mm  X 52 mm.
robotmaker7 months ago
can asy make one much cheaper with a waveform generator ICL8038
IT GIVE SAWTOOTH,square,sine and other circuits can be added to easy,op amp circuits and more
Carlosrhrh (author)  robotmaker7 months ago
I know, but the MAX038 have a bandwidth of 20MHz or more, and the ICL8038 have only a bandwidth of 300KHz, so this is a low cost "high" waveform generator... :)

FabLabLeon8 months ago
Congrats!!
eltercerlugar8 months ago
Amazing job!!!!
THANK YOU FOR THIS!
I just ordered the parts, this is an awesome design around an awesome chip !
I was looking around for a cheap and decent function generator for some time now and I don't have the time now to to deepen myself in making/designing a desent circuit for a diy function generator, but you did al the work for us !
You really helped me, thank you, its highly appreciated !
If you have some problem when you build it, only let me know and I will help you.
guds7778 months ago
is it useful as a 220v 0-60 hz motor controller..
Carlosrhrh (author)  guds7778 months ago
It is not.
swander8 months ago
Very cool. Is there a way to output this to a PC so as to use its display? CRT's are getting a little scarce in small sizes. Maybe mic jack? That obsolete IC can still be had for about $21 US.
Carlosrhrh (author)  swander8 months ago
If you need Know the frequency, I will try to upload a frequency counter as soon as possible.
Edgar8 months ago
Nice!
Voted, and Blogged about it:
http://faz-voce-mesmo.blogspot.pt/2013/11/muahahaha-bolas-de-fogo-e.html
Edgar8 months ago
Nice! Like the Fabbing side of it, too. :)
Voted, and also Blogged about it, too useful to pass un-noticed:
http://faz-voce-mesmo.blogspot.pt/2013/11/muahahaha-bolas-de-fogo-e.html
I really like the box.

Good show.

Joe
pfred28 months ago
That is one expensive integrated circuit. I would hate to let the magic smoke out of that one!
Carlosrhrh (author)  pfred28 months ago
It is more expensive to buy a new one with this characteristics.
It cost to build about 100 euros.
Good to know. The whole project is very interesting and an impressive end result. My only complaint about the article is that if you're going to hype something as 'low cost' right in the title, then saying how much it cost should be right in the project description. I went though every page of it trying to figure out exactly how 'low cost' is low cost'.. heh
Carlosrhrh (author)  hexidismal8 months ago
Hello. I already put a budget attached in the second step.

bben46 hexidismal8 months ago
Unfortunately, 'low cost' is a relative term. In this kind of thing, it's low compared to what a commercial product with similar specs would cost.. Look around the surplus market for that chip, you may get lucky and find one for a lot less.
Yeah the Max038 is obsolete now anyway like the XR2206, best not to make new designs using it.
That's not entirely true, it depends on which sort of performance you want. You could build a high-end 12 bit DDS version that would work quite well up to 10 MHz pretty cheaply using a low-end FPGA, DAC and a good output filter! Total cost would probably be somewhere around 30-40 Euro.

On the other hand, if you wish to go analog:
If you need a low distortion sine-wave oscillator nothing quite beats a Wien-bridge oscillator with a light-bulb is a good choice. For higher frequencies a Collpits-oscillator isn't a bad choice, but keeping it running over a wide frequency range of several octaves is problematic. But I should probably stop before I scare people away. :)
ajoyraman8 months ago
This is good work ! I am a fan of another obsolete part the Intersil 8038 which works well up-to 50 kHz. Unfortunately these analog IC's have disappeared.
aldente468 months ago
Thanks Carlosrhrh
I've had a MAX038 in my parts bin for many years waiting for me to get around to making it a project. Now that I've seen your efforts and your PCB artwork I have been inspired to finally go ahead with it. Aldente46
I love it
Awesome job! Looks very professional!
Carlosrhrh (author)  Infinitevortex8 months ago
Thanks!