Instructables
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.


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.
 
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jmrt1 month ago

i checked the voltage on the vref it is still in the negative range. can you help me what is the problem?

Carlosrhrh (author)  jmrt1 month ago
i think that you must check first that the chip work correctly, because i bought 11 chips, and only worked one. (10 from china and the good one in england).
You can test with an easy circuit, like it is showing in the chip pdf.
you dont have to use this pin, you can use a voltage divisor instead. (see the circuit explanations for farther infor
Carlosrhrh (author) 1 month ago

hello jmrt.

The pin1 (REF) of the chip MAX038 it is a positive voltage, and it is an output.

All the designe of this project is based on the MAX038 PDF.

http://datasheets.maximintegrated.com/en/ds/MAX038...

jmrt1 month ago

hello. we did this project and our supply V- = -5v and
V+ = +5v. but why does the input voltage in pin1 is in negative??:( Vref= -3.5v)

pls help us. this is for our project study.. thank you!! :)

robotmaker10 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)  robotmaker10 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... :)

FabLabLeon11 months ago
Congrats!!
eltercerlugar11 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 !
Carlosrhrh (author)  MethewsEmbeddedSystems11 months ago
If you have some problem when you build it, only let me know and I will help you.
guds77711 months ago
is it useful as a 220v 0-60 hz motor controller..
Carlosrhrh (author)  guds77711 months ago
It is not.
swander11 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)  swander11 months ago
If you need Know the frequency, I will try to upload a frequency counter as soon as possible.
Edgar11 months ago
Nice!
Voted, and Blogged about it:
http://faz-voce-mesmo.blogspot.pt/2013/11/muahahaha-bolas-de-fogo-e.html
Edgar11 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
pfred211 months ago
That is one expensive integrated circuit. I would hate to let the magic smoke out of that one!
Carlosrhrh (author)  pfred211 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)  hexidismal11 months ago
Hello. I already put a budget attached in the second step.

bben46 hexidismal11 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. :)
ajoyraman11 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.
aldente4611 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
desmondtheredx11 months ago
I love it
Infinitevortex11 months ago
Awesome job! Looks very professional!
Carlosrhrh (author)  Infinitevortex11 months ago
Thanks!