Circuit Projects

Bicycle Stereo and Horns (Older Project)

posted Mar 10, 2015, 12:36 AM by Neil Caulfield   [ updated Mar 13, 2015, 11:34 PM ]

Note: anything made prior to college is likely going to have a rather crude style of assembly, though I was quite resourceful with my limited allowance and access to transportation at the time.

Project time frame: Spring and Summer of 2009 and 2010
requirements: basic circuitry, soldering, knowledge of audio equipment

This project put a compact and permanently attached sound system and horn onto the back of a mountain bike. The purpose of this project was to create a bicycle perfect for group cruises at the beach,  and a safer alternative to wearing headphones. It was also a good project to experiment with resistors and LEDs attached to an audio channel.

The design stage involved moving around some components from a partially damaged Altec Lansing 5.1 channel speaker system. I ultimately came up with this 5 speaker cabinet made from the original subwoofer enclosure. The final designs excluded the center channel that would be mounted to the handlebars, but the resources available to me at the time did not provide an easy mounting solution. 

The entire system ran off of a single lead acid battery that was seated in the repurposed water bottle rack. The battery could be removed and charged with a standard automotive trickle charger. 

Early design:
Car horns were added the following year with a relay and switch. This was mainly used for show, and was not ideal for bike trail use as you could imagine. A standard bell was still equipped for such outings. 

Car horn demonstration:

The project has since been abandoned, though possible future plans for an adult-size high wattage stereo trike are a possibility. 

Car Horn Alarm Clock (Older Project)

posted Mar 10, 2015, 12:27 AM by Neil Caulfield   [ updated Mar 13, 2015, 11:35 PM ]

Note: anything made prior to college is likely going to have a rather crude style of assembly, though I was quite resourceful with my limited allowance and access to transportation at the time.

Project Date: Fall 2009
Time to complete: less than 2 hours
Requirements: knowledge of basic circuitry

This simple project can be made for less than $50 and uses common electrical parts. 

  • Alarm clock
  • Horn
  • 12 volt relay
  • 12 volt power source

This project was inspired by KipKay's how-to, so be sure to check his video out for assembly instructions. 

A similar project was done using a bicycle, which can be found here.

PWM Driven Estes Rocket Ignition Circuit

posted Mar 10, 2015, 12:10 AM by Neil Caulfield   [ updated Mar 10, 2015, 12:31 AM ]

Timeframe: 2012 - 2014
Requirements: Analog circuits, soldering, PCB design software, Arduino programing

This circuit was developed in collaboration with Mike Dipalo (his work here) over about 2 years. I did the circuit design work, while he created the code needed for the circuit to function properly. 

The circuit works as follows: The Atmega chip "listens" on the PWM input from an RC radio for the signal to pass a certain threshold. When this threshold is passed, start individually closing four ignition circuits at 1 second intervals. When the counter has cycled, start from circuit one again. If the input signal goes below the threshold(LOW), the entire process will stop, and resume when the input is HIGH again. 

The idea behind this circuit was to make realistic scale aircraft that were capable of launching scale missile payloads. While this idea is frowned upon by some in the radio control community, there are no laws against it. It is, however, against AMA (Academy of Model Aeronautics) rules to launch a rocket motor from a larger moving model. This only applies to AMA sanctioned flying fields.

Early board prototypes began in March 2012, with the final model being produced in late 2013. The board had a total of 4 different revisions. All four were capable of launching from 4 channels in sequence. 

Rev 1 (labeled prototype): Perfboard with relays connected to arduino
Rev 2 (labeled version 1): very large circuitboard with lots of unused space
Rev 3 (labeled rev 2): much smaller, new etching service for less cost, traces were too thin and burned up
Rev 4 (labeled rev 2.1): same as previous version, but traces were edited to be thicker, and the board's color was changed to make it easily distinguishable. 

The videos below are tests of the second, third, and fourth revision respectively. If you had to watch just one, the second video is probably the best. 

Second Revision 
Third Revision
Fourth Revision

PWM LED Driver on Quadcopter - Summary

posted Mar 9, 2015, 11:44 PM by Neil Caulfield   [ updated Mar 10, 2015, 12:18 AM ]

Project Date: July 2014
Total Time: approx. 30 hours
Requirements: Arduino programming language, soldering, understanding of analog circuitry

This project involves implementing some generic 12 volt LED strips onto the arms of a quadcopter frame. This can be done with any RGB LED, but these high intensity strips are ideal for their wide viewing angle and their ease of application. The demonstration below uses simple on-off code, generating 8 colors (red, green, blue, yellow, magenta, cyan, white) by switching on the 3 colors to make different combinations. PWM based control can easily replace this to generate 6 million colors and fade patterns. PWM (pulse width modulation) is a type of waveform that can be used to carry (usually analog) information. The LED's brightness is determined by the duty cycle of the pulse while active. 

A duty cycle of 100% will power the LED at full brightness, 50% will make it half the brightness. This concept combined with the red, green, and blue LEDs allows for a virtually infinite number of colors to be generated. 

The code was set up so the pattern could be selected with a PWM input from an RC radio normally used to drive servos or speed controllers. In the cases below, the AUX channel on my Spektrum radios. 

It can be seen in flight with other modifications here:

A Tutorial for a PWM light controller will be coming soon. 

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