PMBO 2020 Entry Video, Discussion, 1/2 way Through Video, General Thread

~Russ

PMBO 2020 Entry Video, Discussion, 1/2 way Through Video, General Thread
« on November 1st, 2020, 10:50 AM »Last edited on November 1st, 2020, 06:54 PM

https://www.youtube.com/watch?v=5jMb0sK_vEE

Welcome to this years PMBO !! the year 2020 was a bit crazy, but we won't let that stop us from having some fun!

Here are the "official" rules....

FIRST MAKE SURE YOU FILL OUT THE FORM TO ENTER THE CONTEST!!!!!   

Entry Form Here...


PMBO 2020:

Rules for PMBO 2020:
Build a motor that runs on pulses of any energy source or combination of energy sources. (chemical, electrical, radiant, mechanical, thermal or “nuclear”)

If you're entering the contest you're encouraged to Document your process of building the motor and post on the forum as you build.  (Sign up HERE and upload to youtube / media platform and post link)

Please post a total of 3 videos as you progress:

Video #1:“Entering the contest” video can be any length. Video to be posted when entering the contest so we can see where you are starting.
Post Here On This thread...

Video #2  "½ way through" video can be any length. Show your progress and what you have learned so far.
Post Here On This thread...

Video #3  Final video entry, must be no more than 3 minutes long. (not including PMBO2020 intro. If included.)
Post That video HERE ( will be open near the end of the contest)

When is the competition?
The competition will last from November 1st to December 31st at midnight your local time.

Prizes:
There are two competition classes each with different prizes:

Rules for Open class:
Open class is for anyone who want to to join in and build

Prizes:

1st : 50$ credit to Conscious Energies Shop.

2st : 20$ credit to Conscious Energies Shop.

3rd : honorable mention

Rules for Advanced Class:
To enter the advanced class , a donation of $10USD must be made to the prize pool. sent via paypal. (see form below)

Feel free to donate more than 10$...

Prizes:  pot starts at 200$ (donated  by competition host’s) and will be updated as people enter. (100% of the prize pool will be given away)

1st  60% of prize pool

2st  25 % of prize pool

3rd 15% of prize pool

*The winners will be determined by a public poll that everyone can vote on.

Add your own  control element for self achievement EX. speed or angle .

You must post your progress at least at the beginning of your build and ½ way through in the time frame allotted.

Please fill Out This Form Here To Enter The Competition:
FORM HERE

Good Luck And Have Fun!!

If you would like to share this contest, please share this link: https://rwgresearch.com/events/pulse-motor-build-off-2020/

more Q and A can be found here: https://rwgresearch.com/events/pulse-motor-build-off-2020/

Disclaimer: Anything said, read, heard, published, or otherwise associated with doing an experiment for this competition is 100%  responsible for the party participating, Russ Gries or anyone else associated with this contest will not be liable for any actions, harm, or death, that occurs due to irresponsible actions of the party participating. Electricity is DANGEROUS and only users who understand the risks should try to enter this contest.

Don Leibold

Re: PMBO 2020 Entry Video, Discussion, 1/2 way Through Video, General Thread
« Reply #15, on November 13th, 2020, 05:02 AM »Last edited on November 13th, 2020, 01:25 PM
GoGravity ... this is a competition thread about motors we are working on for a competition. I love your video's but if you want attention for your past work leave a link under your current motor. if people like what you are doing they will automatically go to your youtube channel to see what else you are doing. other wize your going to drown out every one else in the competition. Do you remember past years watching competitors video's then automatically going to their youtube page to see their other vid's. Competitive spirit is one thing but giving every one else a fare chance is important.  Can you please remove any video's from this thread that are older then 6 months. It would be so appreciated. Thank you for your patience.

GoGravity17

Re: PMBO 2020 Entry Video, Discussion, 1/2 way Through Video, General Thread
« Reply #16, on November 13th, 2020, 08:03 AM »
Hi, relax, the title says discussion, general thread. All my videos are related to pulse motor build off 2020. If you have any solutions to problems my videos are showing please post them here. If you have any personal comments, feel free to send me a private message. All in good fun :)

~Russ

Re: PMBO 2020 Entry Video, Discussion, 1/2 way Through Video, General Thread
« Reply #19, on November 23rd, 2020, 08:09 PM »
@ Davy,

that is interesting for sure. looking forward to your build. I like the idea that the PMBO brings motivation and gives a deadline. Its all ways nice to be held accountable and to have a working deadline.

:)

@ Luque, as all ways! looking very interesting and complex :) cant wait to see the result!!

~Russ

--Oz--

Re: PMBO 2020 Entry Video, Discussion, 1/2 way Through Video, General Thread
« Reply #20, on December 2nd, 2020, 12:24 PM »Last edited on December 2nd, 2020, 04:26 PM
I have been a lurker for a while in the PMBO threads. I have not entered any PMBO before. I built one, tweaked it a dozen times. When I herd there was another build off, I ordered some more parts (new and better sensors, fets, hardware, etc). My idea was to build a new and different circuit that has been floating around my brain that finally made it to paper, I built it and had some design issues (so far mostly noise issues) and some small wiring errors, after troubleshooting it on/off for a couple weeks it working somewhat. Clarification, it can be run in 3 or so modes, I am currently only in the most simple mode and its drive coil current is in continuous mode, I expected discontinuous mode (I have a couple ideas and needs more test/troubleshooting). My plan is to better my last setup with newer parts/design, but with only a month left, minus the holidays, time is not on my side, I will keep plugging at it, I guess worse come to worse I will enter my previous build. I will soon fill out the entry form. Here is a couple pictures, good luck everybody and stay safe from the pandemic.

--Oz--

Re: PMBO 2020 Entry Video, Discussion, 1/2 way Through Video, General Thread
« Reply #21, on December 15th, 2020, 11:00 PM »Last edited on January 26th, 2021, 03:17 PM
1/2 way though update:

I mentioned in my last post, I redesigned my PMBO circuit, It has new hall sensors (trigger and current sense), fet drive, fets. It has several modes it can be run in and is configurable with switches, jumpers, etc. My new design has 4 fets and lets me drive the fets semi independently. This makes it much more flexible than a single yank the coil to ground topology. One or two coil operation, H-bridge bidirectional drive, complementary coil demag (fet clamping of the flyback voltage).

The $6 hall current sensor is working, but not optimum, it has a offset which can be be adjusted on the scope, but there is sometimes it reports differences compared to the current probe. EDIT: It turns out, the clamp on current probe was showing the inaccuracy's, why, because the exploding magnet fragments would sometimes get stuck in the probe and then show an offset.

One battle I have fought is blowing up fets. After many tests and scope observations, it seems the main failure is repeated avalanche leading to higher temp than the fet can handle, even though it is heatsinked. This is when the fet see's higher voltage than its rating (60V in this part), then it conducts current (even though the gate is off), it sorta acts like a zener, its open till it reaches the breakdown voltage. fets can handle avalanche events of certain energy and freq. These events heat up the fet quickly even with a heatsink. The energy stored in the coil can be quite high and repeatedly dumped through the fet.  If the temp of the fet goes past its rating, then she blows and mostly becomes a short of a ohm or two.

I am driving the coil from 5V to 20v and a current limit power supply setting from 3 to 10A (but the bulk caps can provide 100+ amps), so where does the high voltage come from, flyback from the coil when the fet turn off. This voltage depends on a few factors, fet turn off speed, coil current change (like 30A to 0A) and inductance. I have seen 160A peak coil currents and turn off times of 300ns when driven with 20V (to be fair, that 20V does not stay at 20v under these currents). The flyback voltage is stupid high in these conditions, even in 10A, 10uH in 200ns.
The scope picture has ch2=blue=FET drain voltage, ch3=red=fet gate voltage, ch4=green=coil current.
As can be seen, the fet is avalanching (blue trace has a flat high voltage between the vertical green cursors) at 80V for 640ns at 72A when the fet turns off this is with 10V coil voltage.

There is many ways to handle these voltages, a simple diode of the right size and power rating right across the coil does a great job handling it and many other combinations with resistor/capacitor/diodes and even using a fet. I have smoked a few diodes and resistors trying this. But, and a big but, it reduces/limits my goal. Why, I have a couple theories floating around my gray matter. Remember, these things run off magic smoke, and if you let it out, they stop working. :D

I have run into a number of issues and have solved or improved most of them. In this picture, I finally got the bidirectional working correctly with a simple light resistive load and a function generator input (at a rather high freq to check non-overlap function), another baby step, now I can try some different drive/coil configs I have not tried yet.

Good luck PMBO guys!