Overengineered coilgun

A coilgun that has too many features.

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"Overengineering is the designing of a product to be more robust or complicated than is necessary for its application" -Wikipedia
A few years back I made a coilgun with no knowledge of inductance, electromagnetism whatsoever. Now after many other projects and 1.5 years of electrical engineering study, I'm going to make a mark 2.

Coilgun mark 1 has some defects:
-The PCB it too big
-Coil has too many turns
-Barrel is too wide
-Voltage cutoff is fried

The mark2 should address the previous issues and have some add features like:
-Recording of voltage level when firing
-Wireless read out
-Store multiple shots
and more

During my other projects I have accumaleted a good amount of extra components. For this project I want to add as many of those components and spend as little as possible.
Current list:
-PIC18F452 for the brains
-ESP8266 for wireless transmission
-24LC256 for storage of fire data
-HD44780 display
-Lots of buttons for control
-12V 7AH battery
-4x 2000uF 450V caps
-Thyristor 600V 30A

  • High voltage

    jorisplusplus04/19/2015 at 14:15 0 comments

    After a small break, more progress. Wifi is working and can be updated OTA. The ADC is working. Biggest progress is that the charging circuit is build and working. To find a good PWM frequency and duty cycle for the current goal of 1.5 to 2.0 A I set. I created a small test setup using a frequency generator as PWM source.

    With the test setup I was able to determine that a frequency of 5 KHz with a duty cycle of 50% would result in a current draw around 1.7A. Higher frequency would charge slower and a lower frequency would increase the current without increase the charging speed much. Since the circuit is switching a coil my guess would be that it would generate some noise on the power supply. Oh boy what was I right...

    The source is dipping below 9V. To smooth this a bit I added a 470uF cap on the power connector.

    That's better

    Next up finishing up the code, make the controller board.

  • Schematic update and progess

    jorisplusplus02/07/2015 at 22:05 0 comments

    Finally found the time to make some progress. While I was gone for a while I have acquired ESP8266 modules so instead of the NRF24l01+ I'll be using the ESP8266 for wireless communication. Change of component caused a small change in schematic.

    Progress on the software part is mostly writing the control of the system. The menu is finished and the ESP8266 is configurable with the menu.

    Next up is the PWM out for the charger and the voltage measurement.

  • Schematic and progress update

    jorisplusplus12/30/2014 at 18:28 0 comments

    Progress is going slow. Mostly because of university stuff that take most of my time. I did finish the schematic.

    Schematic consists of 2 boards one for control and one for power electronics that (dis)charges the capacitor bank.

    The plan is to have 4 buttons to navigate the menu and another 4 buttons for switching to fire mode, switching to charge mode, firing and discharging the capacitors. All switches are hardware debounced so programming should be way easier.

    Already have the display working after adapting my own display driver from a lasertag project.

  • Teardown mark 1

    jorisplusplus11/15/2014 at 14:27 0 comments

    The mark 1 had some components that needed to be reused in the mark 2.

    -4x 2000 uF 450V caps
    -300Ω 60W resistor used to drain fully charged caps
    -600V 30A Thyristor GE B1589142
    -Coil mark1 with 2x MUR860 diode and 0.56Ω 5W resistor

    Also the mark 1 PCB that I made without any knowledge what all the components did. With the beauty of 3 parallel diodes soldered on each other.

View all 4 project logs

Enjoy this project?



davedarko wrote 11/15/2014 at 03:03 point
I'd love to see a coil gun where they go the extra mile and make it look like it was stolen from a mad scientist - some cool scifi prop thing that actually works. Good luck with your project!

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controlmypad wrote 11/15/2014 at 01:40 point
I'll be following this since I built a much smaller version for high school Physics extra credit. I knew nothing at the time of the dangers of working with mains voltage. The plan was to drop a nail down an inclined aluminum pipe wrapped with a coil of wire and when the nail hit a conductive plate it would complete the circuit and launch the nail. I really didn't think the teacher would plug it in and fire it for the first time, but he did, and there was a big blue arc when the nail hit, then the circuit breaker tripped and the class went dark, but the nail launched a few feet. Success! Thanks for the memories, I'll be following.

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