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Function generator built and mounted inside electronics bench

A function generator is a handy piece of test equipment to have on-site. [Kammenos] designed and built his own function generator, using the bench itself as the enclosure. You can see above that the control panel presents a clean finished look. To achieve it, [Kammenos] designed and printed the panel labels on a sheet of paper, and used a piece of acrylic to protect it. The circuit inside uses a MAX038 high-frequency generator chip. This is a full-featured part that allows for great control based on a few external components. One of those is a selectable frequency range based on the capacitance value on one pin. This is selectable using a twelve-step rotary switch with a dozen different cap values. There’s also adjustment knobs for fine tuning, duty cycle, and DC offset.

Check out the video after the break for a full demonstration. If you want to build this yourself you’ll need to do some chip hunting. The MAX038 is obsolete. You may still be able to find one, but at around $20 you should be able to source a replacement with the same features and save yourself cash all in one step.

[Thanks Rich]

Comments

  1. dustandechoes91 says:

    We have these at school for labs, there is a panel in the wall and the TA puts whatever signals are needed into them.

    Would kill to have that-or even a function gen at home. Damn good idea on this guys part.

  2. Nice work indeed. For as often as a function generator is used for building and troubleshooting I can see the value of having it “right there.” Nice build and I hope he can get the waveforms stable at the higher frequencies with some tweaking. If I get around to building something like this perhaps I’ll throw in a freq-counter display definitely but kudos to the builder!

  3. anonymus says:

    Nice, but does he have long leads for tricky to move projects?

  4. bogdan says:

    Good design, but don’t know where you can still find MAX038, they are obsolete for quite a long time.
    In fact, if i remember correctly, maxim had these for a special order but produced more in order to get the price down…

  5. gyro_john says:

    Thanks, Kammenos. I like it a lot! If I build myself one, I will add a couple of automatic amplitude settings which will be helpful for me: 5Vp-p output and 3.3Vp-p output. Then I won’t have to manually adjust for them.

    Cheers!

  6. Tomasito says:

    Search for XR2206/7
    They’re pretty inferior but readily available.

    If you don’t need sine-wave, go for the XR2207.

  7. TheFileClerk says:

    I would suggest the XR2206, but it is being fazed out completely in April without any comparable replacement.

  8. TheFileClerk says:

    Doing a quick google search for monolithic function generator ic brings up a few other decent chips including an ICL8038 which with a cursory glance seems like it may do the trick.

  9. zool says:

    i saw this a while back when i was searching for vco chips
    i picked up an XR2206
    but for musical reasons

    you may be able to find the others for cheap on ebay, i know i’ve seen ICL8038s there

  10. There’s lot’s of MAX038 on Ebay though with the price they are going for if I had one I might chose sell it and design my function generator to use something else anyway.

  11. Smoking says:

    Good job! But they are less expensive as you think.
    http://www.atten.eu/function-generators.html

  12. Drone says:

    Yeah, the MAX038 is dead part. Even the designer recommends not building this. Why did HaD post this?

  13. veneficus says:

    The Max038 is about $20 and up on ebay. I’d buy myself a simple function generator from eBay instead. You can find one about $40 if you look for it. If the device is powering up, it is very likely to be functioning (calibration might be off).

  14. Mick M says:

    Futurlec has them:
    http://www.futurlec.com/index.shtml
    for $22.90

  15. bogdan says:

    for $40 you can get a digital DDS chip, a micro to control it and maybe even the lcd. It’s a more complex design but might be worth it.

    Agreed about the xr2206, realy available and cheap, but only 1MHz

  16. fred says:

    @bogdan

    That’s great. Where is your web page that has all of the information to build it?

  17. Tomasito says:

    Just an advice, with the XR2206 it’s REALLY difficult to reach 1MHz, it’ll go up to 100KHz in most cases.
    That’s why I said “pretty inferior”.

    If you came up with a desing that uses a 2206/7 and reaches 1MHz please post it, it would be very usefull for many people (me included).

    All that is, without distortion, off course.

  18. I made this with the MAX038 because i simply found it somewhere in my parts bin, forgotten from a past era… Anyone asking me about this, i discourage him to do it with this chip. XR-2206 could be one solution, but it goes up to 1 MHz.

    The PCB design is very hard and the rest of the parts also was not chosen wisely. Above 10MHz i have some problems with the integrity. I may solve those issues, but not in the near future :)

  19. Middlerun says:

    I’m making a function generator using the XR2206. Mine works up to about 830 kHz. Any higher and the signal cuts out. The waveforms start to distort after about 100 kHz.

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