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What electronics or electrical did you do today?

Discussion in 'Electronics & Electrics' started by /invariance\, Jun 9, 2019.

  1. Matthew kane

    Matthew kane Member

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    Jan 27, 2014
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    Melbourne
    They are 3 separate things. The big chassis with transformers and chokes and the two pre’s I purchased a long time ago from an AWA collector. They used them (along with other modules) in Sydneys AWA broadcast room. I’ve started stripping them down today to clean the chassis and respray, followed by a electrical restoration. They are more show pieces part of Australian broadcast history and missing parts for it to be working again. I plan to auction them off later next year.

    The Stromberg Carlson unit came out of a 40’s radiogram console I found next to my train station. I disassembled the speakers, Garrard turntable and the radio/amplifier unit for restoration (completed now sans the 74rpm Garrard table) and my mate took/completed the restoration on the wooden console.

    They’ll be listed online for sale after the new years.
     
  2. mjunek

    mjunek Member

    Joined:
    Apr 1, 2003
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    Western Sydney
    Looks great there! Now that I've moved house I really need to get my workshop finished being set up so that I can get back into restoring some radios. Got 3 sitting around waiting for attention!
     
  3. dakiller

    dakiller (Oscillating & Impeding)

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    So I've had some old Audioengine A5 speakers laying around that developed a fault making them unusable (massive distortion and crackling sound) and I've kept them around with the intention of stripping out the electronics and rebuilding them. With a spare long weekend, I decided to get going on it.

    What the guts of one looks like -

    91243368_665126427568606_5213037798428246016_n.jpg

    91232831_674646789976504_4065104357169823744_n.jpg

    91333477_1041921939534454_3681845643455758336_n.jpg

    91390765_522391848424154_2542398361789530112_n.png

    91865070_220110709200666_233370290728468480_n.png

    91517170_803486850161950_7540736182519332864_n.png

    This is the amplifier board design so far. Designed around the TPA3245A Class D amplifier, it is pretty much the datasheet reference design.

    The A5 transformer has 19-0-19 V windings, so centre tap rectified to straight 25v dc out, should be plenty to drive the speakers in bridged drive mode.

    The right side of the board is just the original crossover circuit copied and re-implemented.

    The IC needs heatsinking, and has its thermal pad on top, so those holes either side of the IC will bolt some L channel aluminium in and mount to the original A5 heatsink just fine.

    TODO - design the input circuitry side. Plan on putting in a high quality DAC, bluetooth receiver and a raspberry pi running volumio and Apple's Airplay.
     
    mAJORD likes this.
  4. cvidler

    cvidler Member

    Joined:
    Jun 29, 2001
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    13,535
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    kicad do that 3d modelling as well?

    I haven't done any pcb design since I moved away from windows (and Eagle), I have kicad installed, but done nothing more than poke around.


    As fro today/recently, got a bunch of arduino's onthe desk, prototyping a transmission controller. an update from a prototype I did ~10 years ago from discrete 74 series logic.
     
  5. dakiller

    dakiller (Oscillating & Impeding)

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    Yep, that's a Kicad 3d render. I've found the 3d render very good at checking the silkscreen layout, as it is a much better representation of what the output will be compared to the main 2d layout.

    I moved off Eagle to Kicad around version 5 or 6 of it. The latest Kicad is really good once you learn all the keyboard commands you have to know to use it.
     
  6. merlin13

    merlin13 Member

    Joined:
    Apr 12, 2003
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    Location:
    back in BrizVegas
    Not today, but last Tuesday...

    Acquired a dead late-generation 42" TV 'n remote at Almost, Not Quite The Right Price, being sold because "...it suddenly stopped working last week, the quote to fix it was almost as much as buying a new one...".

    30 minutes later after a splash of liquid flux and some serious abuse with the hot air tool, upgraded the Missus from her 32- to a 42" Smart TV.

    Perfect timing too. Couple of weeks ago she was mumbling about sinking $500 or so into a bigger TV...
     
  7. dakiller

    dakiller (Oscillating & Impeding)

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    Continuing the A5 speaker revamp

    Schematic for the input circuity 95% done.

    Idea is to have inputs coming from the original two analogue inputs on the A5, as well as a raspberry pi that can do any sort of streaming input - bluetooth, airplay, internet streaming, etc.

    The best way to get high quality sound out of a raspberry pi is using an external dac using I2S digial audio data. Taking it up a notch is to provide the master reference clock to the raspberry pi and not rely on some crappy pll to generate a jittery clock.

    Audio has many different sample rates, but fundamentally, there is only 2 clocks that you need, and the rest is just integer multiples from them. So providing 2 clocks, needs a custom driver some logic in the raspberry pi to switch on the appropriate clock. Lucky most of this hard work has been done and is pretty cheaply available in the HiFiBerry DAC PRO - https://www.hifiberry.com/shop/boards/hifiberry-dac-pro/

    The PCM5242 DAC is controlled by the raspberry pi over I2C to do all the clock control, and it effectively makes the PCM5242 the I2S master controller and the raspberry pi slave clocks off that.

    A means to then be able to input analogue sources into this DAC is needed as well, that is what the PCM1864 does, and can be configured to be a slave on the I2S bus, as well as a digital MUX, where the audio data from the raspberry pi is also fed though the PCM1864 before going to the DAC.

    The PCM1864 also can do digital volume control, and spare analogue inputs can be read by a dedicated ADC in it to measure the voltage on a pot that can be read and used to do volume control.

    Add an ARM Cortex M0 micro as some basic control for everything and a bunch of power supply stuff and you got a pretty high end streaming ADC/DAC

    a5input.png
    a5inputbrd.png
     
    mtma likes this.
  8. dakiller

    dakiller (Oscillating & Impeding)

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    Input DAC board just about done.

    a5top.png
    a5bottom.png
    a5middle.png
    a5rendertop.png
    a5renderbottom.png
     
    ericks likes this.
  9. OP
    OP
    /invariance\

    /invariance\ Member

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    Really taking those A5’s up a notch or 3.
     
  10. Dice

    Dice Member

    Joined:
    Feb 18, 2002
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    Altona
    Work in progress for uni - haven't had a great deal of experience with surface mount stuff, 0.5mm pitch in particular.
    This is the second revision of a piece for my final year project.
    Altium 3d view.PNG
    It's coming along ok ... aside from the solder bridge I just spotted.
    2020-04-11 11.25.05.jpg

    Efm32 as main microcontroller, retrieves data from a piece of industrial equipment over an annoyingly proprietary layer above CAN, checks if data is worth logging, adds a timestamp (stored on an RTC, accessed via I2C), logs to an SDcard over SDIO. Log can be accessed over wifi by connecting to an esp32 which retrieves data from SDcard via efm32 over SPI. Designed in Altium.

    Wow that's a lot of acronyms.

    If it all works I'll be stoked - I made the novice mistake of thinking the manufacturer app note code would be be good enough for proof of concept code :p
     
  11. dakiller

    dakiller (Oscillating & Impeding)

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    Nice board.

    You should move to 0805 or 0603 on your passives next time. They aren't that much harder to solder and you can make much better layouts compared to 1206 which are huge in comparison.
     
  12. Dice

    Dice Member

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    Thanks! And fair call - I wasn't sure how I would go with the hot air soldering, now that I've got it down with the larger size I've a bit more confidence to try the smaller ones.

    Your board is a couple of levels out of my current comfort zone - I found QFP hard enough to solder, leave alone QFN, and anything to do with audio is black magic to me. Nice component density too
     
  13. dakiller

    dakiller (Oscillating & Impeding)

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    I did mobile phone repairs many years ago, so anything short of high density BGA's is just fine. If you've got a hot air, then with a bit more practice, you should be just fine with the QFN's. Watch some Louis Rossmann repairs on Youtube, he does some pretty tricky soldering work.

    Audio is what I learnt nearly all my electronics knowledge on many years ago. I haven't done any for years and years now, so it is nice to jump back into it.
     
  14. OP
    OP
    /invariance\

    /invariance\ Member

    Joined:
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    Here’s something I have been working on in the last few days, re-homing this old girl
    1DA3B7A2-4AF4-46D4-B310-983B92E93002.jpeg
    Must have been sitting under flouros its whole life
    3D3C9258-9479-4783-90B9-2E05B860DFFB.jpeg
    5B11DB80-CDA6-4DDF-9277-F40F4A38CC48.jpeg
    I think every time I touched it something would break. Fortunately have a few boxes here so I didn’t have to spend anything, win win.
    C9AEF052-EA95-4BAE-8240-112F0FB4CA68.jpeg
    D7F672DD-DFAD-460F-B664-E3B899CC5585.jpeg
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    came up a treat with room to put the solder and flux on top.
     
    technoir, _zak, merlin13 and 3 others like this.
  15. _zak

    _zak Member

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    Oct 12, 2009
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    Technically yesterday, but spent some lockdown time creating a breakout board. It was small enough to get put on one of OSH Park's Super Swift panels too!

    samdbreakout.png
     
    ericks and dakiller like this.
  16. oculi

    oculi Member

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    Twisted some wires together until some self xe-energizing motors did what they were supposed to.
     
  17. dakiller

    dakiller (Oscillating & Impeding)

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    Got a new toy
    CF960665-D55B-4053-A2E1-284F450C81F7.jpeg

    3405E38C-C6F0-4242-B9E7-9B0BC8CAE4AC.jpeg
     
  18. Matthew kane

    Matthew kane Member

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    Restored an AVO tester yesterday.
     
  19. ArmoureD

    ArmoureD Member

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    Show us.
     
  20. Matthew kane

    Matthew kane Member

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    [​IMG]
    mk2 waiting for 6 shunt and load resistors from E14. Arriving soon.

    [​IMG]
    Complete overhaul on this mk4 including new meter. Very expensive and rare. Panels still need to be blasted and painted.


    [​IMG]
    T
    wo panel tester I did other day. I have 3 of these including one Admiral Pat version.
     
    kombiman and ArmoureD like this.

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