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DDS generator, my version of the Chinese module housing.

dudik56 10074 34

TL;DR

  • A Chinese DDS generator module gets a custom metal enclosure with a CD-ROM drive front, replacing the original makeshift battery-and-converter setup.
  • The front panel uses dibond glued to the modified drive face, while the ring, keys, and knobs were turned from aluminum after recycled parts proved too flimsy.
  • A universal-laminate supply generates +12V, -12V, and +5V with LM78XX, LM7912 stabilizers, and a 2x12V transformer.
  • The smoky display window carries foil labels that stay readable with backlight, and the finished unit now sits neatly on the shelf.
  • No schematic is included, and the power switch had to move to the back beside the transformer because the front panel was too cramped.
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  • #31 19261356
    dudik56
    Level 17  
    Posts: 351
    Help: 5
    Rate: 609
    The OHS course was done and good, but when you think about how many devices with PE wire are connected to sockets with two holes without PE and this is a mass phenomenon, it smells a bit fearful hypersensitivity. Tin PCs commonly used in homes are usually incorrectly plugged into ordinary sockets and somehow no one makes a problem out of it. Thanks for your comments, I will take them into account when installing the device permanently ;)


    I have already ordered the thinnest 3x0.5mm2 cable I found for these 2.5W of power ;) and when he gets there I will change him. OKAY?
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  • #32 19261597
    .Wiśnia
    Level 28  
    Posts: 1604
    Help: 77
    Rate: 76
    Nobody is oversensitive here, if you invited a specialist for periodic electrical measurements to your home, he would point out the shortcomings because that's what he is for. The other side of the coin is the insurer who, if he does not see the paper, then ... but not about it.

    The cable is selected for the protection, not the power of the device. You have a glass fuse with some value, say 1 A, you count the power of 230W - in a short circuit even more according to the characteristics of the fuse. We are talking mainly about fire protection for long-term load on the cable.

    That's the theory and you practically do not meet cables smaller than 0.5mm2, so your choice will be good.

    I am happy with your purchase
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  • #33 19261660
    dudik56
    Level 17  
    Posts: 351
    Help: 5
    Rate: 609
    The cable is too thick anyway, because I have a 63mA fuse, but as you mentioned it would be difficult for me to buy a lighter one, although I would like to be smaller.
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  • #34 19263396
    dudik56
    Level 17  
    Posts: 351
    Help: 5
    Rate: 609
    You can now sleep well, the recommendations are made ;)
    DDS generator, my version of the Chinese module housing.
  • #35 19263410
    .Wiśnia
    Level 28  
    Posts: 1604
    Help: 77
    Rate: 76
    and that's beautiful, remember for the future: you must not use a foreign earthing if you connect the voltage to the electricity network separately.
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Topic summary

✨ The discussion revolves around a DIY project involving a Chinese DDS (Direct Digital Synthesis) generator module. The creator expresses dissatisfaction with the original module's makeshift design and lack of housing, prompting them to construct a custom metal enclosure using scrap materials, including a front panel from a CD-ROM drive. The power supply is designed with LM 78XX and LM7912 voltage regulators, and the user addresses concerns about safety, grounding, and insulation. Feedback from other users includes suggestions for improvements, inquiries about the generator's performance, and discussions on electrical safety standards. The generator reportedly provides stable frequency output, with modifications made to enhance its functionality.
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FAQ

TL;DR: Re-casing a €12 Chinese DDS generator in a CD-ROM box delivers ±1 Hz frequency agreement and “very respectable” stability [Elektroda, dudik56, #19258591; Elektroda, kapi11711, #19259677] while upgraded wiring adds 3-core 0.5 mm² cable and ≥6 mm 230 V spacing.
Why it matters: Smart safety and layout tweaks turn a bare board into a reliable lab signal source for pennies.

Quick Facts

• Frequency span: 0.01 Hz – 10 MHz typical for AD9850/AD9833 Chinese DDS boards ("DDS Function Generator"). • Accuracy: ≤ 1 Hz deviation at 1 kHz vs. counter [Elektroda, dudik56, post #19258591] • Output swing: 0 – 20 Vpp selectable with onboard op-amp [“H11887 install manual”]. • Mains section: 2 × 12 V, 2.5 VA transformer, 63 mA fuse [Elektroda, dudik56, post #19259195] • Safety clearance: 6 mm PCB-to-case gap after fix [Elektroda, dudik56, post #19259195]

1. Which DDS board is used and what range does it cover?

The build uses the common H11887/AD9850 DDS module. Its sine, square and triangle outputs span approx. 0.01 Hz to 10 MHz, with 0.01 Hz resolution according to the kit datasheet [“H11887 install manual”].

2. How precise is the frequency output?

At 1 kHz the module’s display and an external counter differed by no more than 1 Hz, giving a 0.1 % error budget [Elektroda, dudik56, post #19258591]

4. What power-supply topology was chosen?

A 2 × 12 V, 2.5 VA PCB transformer feeds LM7812, LM7912 and LM7805 linear regulators, yielding +12 V, –12 V and +5 V rails [Elektroda, dudik56, post #19257919]

5. How do I route 230 V safely inside a metal case?

Keep live traces ≥ 6 mm from metal, insulate the standoffs, and use a rear power switch to shorten mains wiring [Elektroda, dudik56, #19259195; Elektroda, ^ToM^, #19259830].

7. Which power switch fits a shallow front panel?

A miniature PCB switch actuated by a long plastic rod lets you mount mains components at the rear while retaining a front button, a practice used by Philips and Hameg instruments [Elektroda, ^ToM^, post #19259830]

8. How can I turn an old optical-drive shell into a lab case?

How-To:
  1. Strip the DVD-ROM, keep the steel frame and aluminium front.
  2. Mill openings for BNCs, display and keypad; bond a Dibond overlay for labels.
  3. Mount boards on plastic standoffs and close with retained screws. Total time: ≈ 2 h [Elektroda, dudik56, post #19257919]

9. What mains cable and fuse ratings should I choose?

Match fuse to worst-case short-circuit. The build uses a 63 mA glass fuse and a 3-core 0.5 mm² cable, providing > 4× thermal headroom [Elektroda, dudik56, post #19261660]

10. Can I obtain continuous frequency tuning instead of decade steps?

Standard firmware steps digitally; for audio sweeps you can add an encoder-driven “fine” menu or upgrade to an AD9834 board offering 0.004 Hz resolution [“DDS Function Generator”].

11. What are common failure or hazard edge cases?

Edge cases include standoff creep reducing clearance below the IEC 61010 5.5 mm minimum, and a loose live wire touching the case, causing shock risk. A 3-core cord and strain-relief clamp mitigate both issues [Elektroda, pawlik118, post #19259133]

12. Where can I get full schematics and code?

Download the original PDF manual from Dropbox [Elektroda, dudik56, post #19258791] or check the open-source design on Electronics-Lab (“DDS Function Generator”).
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