• Humming noise

    lion mclionhead • 07/27/2026 at 22:51 • 0 comments

    So the humming noise got louder as power decreased.  It was quite a miserable humming sound at 5, bearable above 7, reminiscent of the back rooms.

    The most efficient way to generate a quieter sine wave is an old fashioned autotransformer.  

    https://www.amazon.com/YaeCCC-Transformer-Variable-Voltage-Regulator/dp/B076Y2XHRS/

    The standard variac everyone has used for 100 years.  The homeless despot has a better deal. They're actually household items, not as cheap as a dimmer switch but far less than what lions expected.  It's actually the same price lions spent on the dimmer switch, relays, meanwell.  It would have just been the total price up front instead of incrementally.  It would have to go on the floor, with the user interface broken out to a separate panel.  This split arrangement would actually allow the front end to have a proper LCD.  It's quite an investment in space for just controlling a blower.  A common dimmer with all its humming was good enough for a much younger lion.

    Commenters noted the variac hums at full load but no-one has ever captured the humming sound.  The blower wouldn't run them at full load.  Note if the input & output on a variac are swapped, it becomes a voltage booster.

    Given the investment in speed controllers already equaling the cost of the blower, adding a variac would bring it to 2x the cost of the blower.  Thoughts turned back to developing a custom blower around a low voltage motor.

  • Display ugrade

    lion mclionhead • 07/25/2026 at 08:46 • 0 comments

    Went with a 10 segment LED bar graph.  5.1V across 1k was bright enough for all of them, even with 50% duty cycle.  A wider space between 5 & 6 would aid reading, but in practice, this proved not wide enough.  Some blue indicators would show the on & bypass state.  

    It had 1 less power level than the digital readout so this saved 2 pins.  The only thing of this size in the apartment, which can withstand soldering was wood.  Naturally, there wasn't enough space for the farsteners.

    The LEDs were 15 year old scraps which were sanded down to make them satin.  3mm was believed to make it easier to differentiate the segments than 10mm.

    The minimum power level was 1 led.  It absolutely needs 1 LED always lit to show it's powered on.

    Power on was left blue.

    Then LEDs advance with higher power.

    Servo hard over is 10 LEDs.

    Maximum power with bypass is shown by right blue.

    It reminds lions of old appliances made for handicapped animals.  Along with the giant digital readouts, the apartment definitely exudes accessibility for a visually impaired lion.  A younger lion could see a clock radio across the room or a TV from a sofa across the room.  There's no turning back the clock.  Surgically fix near sightedness & lose close focus.

    There was a vision of a new front panel with holes just for the LEDs & IR, but this would reduce the visibility compared to a large opening.  It's important for the opening to look happy, in the dark.

  • Enclosure

    lion mclionhead • 07/23/2026 at 23:41 • 0 comments

    A new enclosure to better fit in the apartment began, with an improved raspberry pi adapter.  This would now power the nozzle & the dimmer.  Helas, the new adapter broke the micro.  It would now lock up when the servo was fully deflected.  The bench power supply actually showed more ripple when the servo was hard over than the raspberry pi adapter.  

    It seemed the micro was detecting IR pulses continuously when the servo was hard over.  Some really high frequency signal in the raspberry pi adapter was triggering the IR sensor when the servo motor was running.  A 1k + 220uF RC filter got the IR sensor to work.

    So, it cost a lot more in terms of time & spare parts than a commercial option, but it worked exactly the way it had to, with exactly the right range, exactly the right buttons, exactly the right display.  It wasn't anything to be proud of, so made a low production quality video of the mechanisms.  

    A more practical RC dimmer would just directly drive a triac from a microcontroller.  It would sense a certain voltage or time at which to toggle the triac & lions already have a spare triac with all the optoisolation.  It wouldn't need relays for a bypass or shutdown.  The enclosure wouldn't shrink by much.  It just wasn't seen as worth the development compared to a mechanical pot turner.   It wouldn't have any back EMF protection, since the triac's spudger capacitor never worked.

    Progress continued on PLA-coroplast enclosures.  The mane problems are bonding the side panels while allowing the top panel to be removed, having enough material to bond the end caps, spreading the load on the PC board farsteners.  PLA load spreaders have been promising.

    This one has the 5V for the nozzle broken out, the output panel from the inverter still being used to save money.  The output power switch & LEDs aren't connected.

    Getting all 4 panels on requires edging the end panels on diagonally & slightly flexing the side panels.  The corners are bonded with packing tape.  There might be a way to install some right angle farsteners on the inside that don't extend the full length.  It's already a bit farstener heavy with 8 6-32's on the end pieces.

    The blower installation made it clear that lions couldn't read the display.  The only indication of the setting was the sound of the servo & relay.  The IR reception was also terrible.  That needed to go outside the panel.

    The only larger display in the apartment was a 30 year old clock, but it was a bunch of board mounted LEDs with a diffuser.  It was also really dim by modern standards.  At this point, a charliplexed LED bar graph was looking more likely but it would entail a completely new front panel.  

    Initerestingly, that 30 year old clock used manes frequency as an oscillator. The internet says it's far more accurate than any equally priced crystal, to this day.  The number of manes cycles is synchronized to an atomic clock on a daily basis.

  • Bringup

    lion mclionhead • 07/22/2026 at 04:45 • 0 comments

    To remotely control a blower, the lion kingdom would be hooking an el cheapo dimmer.

    to an el cheapo servo.  The same dimmer 20 years ago, for 1/2 the price, was hooked up to a fan & proven to do a good job at speed control.  They just chop the sine wave so they don't get hot.  The useful range with an inductive load is a tiny fraction, but this tiny range can be resolved with software.

    Chinese alternatives were nosebleed expensive & lacked any display.

    It was immediately found to have a nearly 360 rotation to go from off to full power.  The useful range for the blower was the top 50%.  Instead of a complicated mechanism to make the servo go 360, a relay for turning it off was a simpler option.  It was also found to cut off slightly below 100%, so a 2nd relay would be required for a bypass mode.  It would need 2 relays to have off, dimmer & bypass states.

    This was the 2nd project to use a PLA servo attachment.  Just heat the PLA & press it on.

    The enclosure was reused from the failed inverter project.  This servo mechanism was very precise.  It had to be installed with the dimmer & servo at maximum.  The servo had a 3 second timeout to avoid running the motor constantly.

    Maximum PWM was .5ms.  Minimum was 2.5ms.

    Stock wattage on low was 67.  Decided to make 60W on medium or 1.5ms the new minimum for cold winter nights while not stalling the motor.  The servo's full 180 deg was .5ms to 2.5ms so it would only be going 90 deg.  

    The trick with this, like a lot of coroplast enclosures, was weighing it down.  The smartest design would probably have it narrower, with all the plugs in back & display in front.