D. Edward Mitchell 16:00, 14 April 2020 (UTC) Hello World!    groupKOS Developer Share UNDER CONSTRUCTION

MOT DC Power Supply Project

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Project Status: Imaginary | Documenting | Documented | Implementing | Complete

12:00:00 AM GMT Jan 1, 1900 Developer Msg:    Standby for startup. MOT Priority, medium high. MOT Testing and Handling is top on MOT list.


A one-kiloWatt high-voltage microwave oven transformer. Danger! Electrocution hazard! Lethal voltages at 2100 Volts AC.


Don notes while morphing this page from pipe dream toward production worthiness

This project is a DIY DC power supply made with a microwave oven transformer (MOT), plus some heavy full-wave diode bridges [1] . Nuts, bolts, custom connectors (big ones), with tools and TLC make a family heirloom.

  1. Full-wave diode bridges: 10pcs Single Phase Diode Bridge Rectifiers, KBPC5010 Diode Bridge Rectifiers 50A AC to DC 1000V, $12.79 free-shipping (Prime).

  2. But then, some over-kill engineering and a feature set a closet alchemist can appreciate —and what's to keep the best power supply project at 7.8 kilo-foot(s) from being an overwhelming lure to click...

    The Button

    Design vectors

    1. Stringent ergonomics
    2. Prudent over-kill safety
      Magnetic-latching power-on switch (power-off interrupted)
    3. artistic style may be applied
    • cleaved selenite for light-pipes to transfer panel indicator lights from an LED to the panel display surface
    • grocery-bags re-melted into cabinet foot pads
    • Precision laser-pointer-Galvanometer rear-projection-on-translucent-scale (in the box, projecting to a transparent wood inlay)
    • Vernier-dials with Moiré patterns Vernier-morphing (like numbers appearing in the pattern per the rotation of a dial)
    • Delay-on / delay-off
    • Threshold relays and range monitors (from a DIY automation library developing standard home automation components
    —A DIY manual for intelligent people –with pictures
    • Water cooling fittings (in/out)
    • Stackable case joiner frame, and a joiner-frame on castors for under the stack.


    The Alchemist's Options for Power Supplies

    1. Locking castors
    2. One handle for lugging around
    3. Alexa enabled
    4. Two handles for lifting with a friend
    5. Works upright or downright
    6. Air-ducting to re-purpose waste heat as a heated Ottoman
    7. WiFi MQTT internal telemetry (temperature, volts, amps; average/highest/lowest/present/yadee)
    8. Smart option w/Android app and software power-control-profiles for charging batteries, electrocuting fishing worms, etc.
    9. Embedded MQTT server hosting telemetry for any wireless automation in the home (likely on a Raspberry Pi)

    Really expensive option

    Vintage industrial high-dollar parallelogram lift system, for when the cabinet-top working surface needs precision vertical alignment.

    Really simple DC power-supply circuit schematic

    The power supply outputs connected backward

    'Backwards' means, put the lines voltage (120 vac) onto the fine-windings of the MOT, normally the secondary high-voltage output windings. When wired backwards, the voltage output is at popular levels for people like us.

    MOT backwards output Unrectified: 14 VAC (unloaded) MOT backwards output Rectified: (14 * 1.414) = ~20 VDC (unloaded)

    If an MOT is used backward for modest loads (under 20 amps at 12 vdc) the thermal loading of the MOT is negligible (get a second opinion!). But! Ventilation is required to avoid heat build-up. Enclose only in a wafty box, breezy.

    MOT Spec-s

    per Jochen's High Voltage Page

    Microwave ovens contain a very powerful high voltage transformer (MOT = microwave oven transformer), see photo. A typical output voltage is 2kVeff, at around 1000W power. This is equivalent to about 0.5Aeff output current @ 2kVeff output voltage. The short-circuit current is even higher.Dec 30, 2004


    MOT load limits

    These backwards ball-park figures need verification with tests. Stay tuned.

    A 20-amp circuit breaker, loaded at 80% pulls 16 Amperes AC In wattage that's 120 X 16 = 1920 watts. That's a good target to stay below for a respectable power supply that may pass down for generations.

    An MOT DC supply would, roughly estimating, produce 50 Amperes DC against a 1000 Watt load.

    Load-limit by the user beneath smoking-threshold is advisable.

    My grandmother always said, "Don't draw more wattage from your MOT power supply than the original microwave oven was designed to handle." Plus, air-cooling is required for periods of high-current use that would smoke the coils without cooling. Grandmother hated that.

    MQTT (MQ Telemetry Transport) is an open OASIS and ISO standard (ISO/IEC PRF 20922) lightweight, publish-subscribe network protocol that transports messages between devices. The protocol usually runs over TCP/IP; however, any network protocol that provides ordered, lossless, bi-directional connections can support MQTT.

    The video series: The Evolution of a microwave oven transformer to an IoT telemeterized and remotely controlled precision (ish) DC 30 ampere power supply with configurable settable ranges and thresholds and a cup holder

    You feel an urgency to find The Button

    Safely removing a(an) MOT from a microwave oven's insides

    Testing the MOT for what it is

    Shameless use of the MOT for what it is

    An MOT demands caution !

    power supply evolution in DIY video series

    Every techno-geek needs a custom power-supply on the web
    Do you know anyone with a power supply that has its own Tweeter account?
    Inspire the design evolution with your comments!
    Enter your comments on the YouTube video.
    Comment directly to Don aght groupKOS doght cφm.

    How to talk to a(n) MOT

    1) MOT are you there?

    MOT.status.on = true
    Response: True, or nothing if not there.

    2) MOT.respond

    Alias of #1

    3) MOT.report

    Response: A JSON or HTML or CSV file is returned containing named values of telemetric data.

    4) MOT.set(name, MOTley)

    5) MOT.set(datetime, yyyy.mm.dd.hh.mm.ss)

    6) MOT.set(output, 4.99v)

    Response: A named-value of the current voltage reading, e.g., "Output: 4.99v".

    7) MOT.set(current-limit, 40 amperes)

    8) MOT.set(supply-line-breaker-threshold, 16 amperes) (A soft-breaker)

    9) MOT.login(username, security-key)

    Response: Status report. See #3.

    References

    MCITransformer.com

    Power Supply Design Notes
    https://mcitransformer.com/about-mci/power-supply-design-notes/