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2024-05-23, 07:16:48
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Author Topic: William ENKI  (Read 6632 times)

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Posts: 409
Be the change you wish to see in the world
Glad it helps - I'm really just throwing ideas out there. Good to conceive of every possibility and account for it prior imo.
Look forward to the next update  :)
   
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Posts: 243
The PCBs arrived from JLCPCB via Fedex today.

I've completed a manual continuity check and it all looks good so far. Now onto the soldering!













Upgraded cooling compared to last revision of PCB - big bro & little bro

   
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I soldered the components in. I opted for the Microchip MSC035SMA170B4 MOSFET in this board.

The biggest time sink is finding and organising all of the components, gathering them into one place.





The back to back heatsinks were a bit of a squeeze. Ideally there would be another 1mm inbetween them. As it stands they aren't perfectly level, but I think that was because I had to bend the MOSFET & diode legs slightly so that the backs would sit flush against the heatsink.
   

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Posts: 409
Be the change you wish to see in the world
Good to see the project advancing steadily  O0
A meticulous, chronological, bullet-pointed list can help immensely with components ime.
“ Give me six hours to chop down a tree and I will spend the first four sharpening the ax.”
   
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Posts: 243
Never a truer word spoken. Organisation is the key.

Johnny 5 is ALIVE!



   
Group: Tech Wizard
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Hi Lee,

Great progress and build, thanks for showing the boards too.

Perhaps you wish to tell some more on Johnny 5 circuit? 

Gyula
   
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@Gyula - I'll post the circuit once I've finished it. It's still a work in progress right now.

I've completed all 10 boards nows. Here they are waiting for a final wash / rinse to remove the flux.



I washed them and rinsed with isopropyl alcohol this morning.

I've also tested them all with a 12V incandescent bulb and they are all working as expected, at this voltage level at least!

Next step is to build a circuit with the 74HC4017 chip, and combine that with an inverted PWM signal.
   
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Hi Lee,

Thanks, well I meant not a schematic, sorry but the purpose of the circuit because I did not always follow this thread (got lost).   :) 

Gyula
   
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Posts: 243
Hi Gyula,

Ah right, yes, you've got a point. I've changed my approach from what I said earlier in the thread.

I'm now working on a circuit to discharge 10 capacitors in sequence, whilst charging them in parallel (when not being discharged).

I put together this infographic to describe what I'm trying to achieve:



Basically, I want to turn on each MOSFET for a very short period of time, roughly equal to about 0.1t (or less) of the capacitor discharge curve. My thinking is that it will take a relatively short time to refill the capacitor from, say, 95% to 99%. The capacitor will yield max voltage and max current (hence max power) for a short period of time.

Best regards,

Lee
   
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Posts: 243
I got my 74HC4017 circuit working. The circuit takes the output of the PWM generator as the clock source, and then switches between each output in sequence. You can't see from the photo, but each LED lights up in sequence. Once you go above 100Hz then all of the LEDs appear to be lit, but they're actually being lit sequentially.

I added the LEDs as a visual indicator about what's going on. I am planning to take the signal output from each pin on the 4017 and feed each one into a different MOSFET driver logic input (non-inverted). I'll then feed the inverted PWM signal into the inverted input on the gate driver, and both non-inverted and inverted inputs will be ANDed together and this logical product will be reflected on the output. I'll also feed the non-inverted PWM signal into the clock input on the 4017.



Next up I need to adjust my Arduino code to output both a PWM signal and its inverted output. Thankfully I'm using a library (eFlexPwm) that someone wrote to work with the hardware PWM timers on the NXP IMXRT1062DVJ6 ARM Cortex-M7 CPU. The library makes it super easy to generate PWM waveforms.

I'm using the Teensy 4.1 Arduino board for my project. It's the fastest Arduino board out there right now. The CPU runs at 600MHz.
   
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I've now connected the Teensy 4.1 with the 4017 IC.



I'm generating a PWM signal on submodule 1.3. This submodule has two PWM channels - A & B. Channel A is set to output a PWM signal and channel B is set to output the inverse of channel A. I'm able to configure the PWM settings at runtime through the rudimentary web interface that I put together.



The PWM output from 1.3A is fed into the 4017 clock signal input, so each PWM pulse triggers the 4017 to select the next output in sequence. The PWM output from 1.3B is fed into the gate driver inverted input, and output 1 on the 4017 is fed into the gate driver non-inverted input.

Here's a video of it in action. The blue LEDs light up as each output is selected by the 4017. The incandescent bulb only lights while output 1 is high.

https://youtube.com/shorts/Jb_VccmVMYs

I now need to hook up the remaining 9 MOSFET driver boards and test with more light bulbs.
   

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Be the change you wish to see in the world
Tidy, looking forward to the next update.
Should be pretty epic in its final form!
Inspiring stuff  O0
   
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I've finished the 10 MOSFET driver boards and have hooked them up.



I've been ironing out some wrinkles the past few days. The gate driver signal was being distorted and I finally figured out why - I had stupidly put two small capacitors on the logic input, so the Arduino output was trying to charge them up each cycle but never quite managing it. I was left with a somewhat sawtooth waveform rather than a nice sharp square wave. I desoldered the two caps from each input and it's working as expected now.
   
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