David Scholten-
Playing some MIDI tunes on piezo buzzers!
07/08/2020 at 22:42 • 0 commentsOne of those things that is simple to implement with libraries, but very delightful to experience!
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Snippet No.6
07/23/2018 at 11:08 • 0 comments35 lots of 3-6hr prints and a kg of filament later... I have my 80cm Shanghai Oriental Pearl!
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See: https://www.thingiverse.com/thing:1622786/ for the designer of the print and https://www.thingiverse.com/make:517373 for the "make".
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Snippet No.5:
07/14/2018 at 12:31 • 0 commentsFinished printing a kinetic water sculpture from Thingiverse:
See: https://www.thingiverse.com/thing:2542655 for the file and https://www.thingiverse.com/make:518086 for the "make".
My Projects
My Pages
Things I've Built
USB-5V to 24V Super Capacitor Power Buffered Boost Converter
This DC/DC converter takes 5V from the Teensy 3.6 USB supply and converts it to a voltage of up to 24V. The balanced string of eight 50F/3V capacitors (total: 1800J) allows for bursts of currents of 10A+ and very simple/slow voltage regulation.
Old Autonomous Ground Based Robots
At uni I worked on multiple different ground-based object avoidance robots for internal competitions. I usually did the electronics in the group. See: https://youtu.be/Pz4EyufTE1I
https://youtu.be/hpXHC-0ChTs
https://youtu.be/V_LOAbyKjMI
First Class D Audio Amplifier
This self-oscillating class-d audio amplifier was not my design. However, what was special about it was that it was the first switching power converter I ever constructed. This made it the defining project that shaped the direction of my career.
Very First Linear Power Supply
This old thing had an output of +/-30V@3A and an auxiliary output of +/-12V@1A. It basically powered the majority of my breadboard projects early on (mostly audio related). It even had a variable speed fan controlled by the heatsink temperature!
Tribute to the Failed/Forgotten Projects
To those projects that failed, frustrated or outright exploded; To the projects that ended up being redundant duplicates, ultimately teaching me nothing new... You won't be missed. Seen in picture: The 450 RC heli that exploded in flight. RIP.
RC Quadcopter with Video Downlink
Although there was no auto pilot, this old custom FPV quadcopter had IMU based stabilisation, stupidly bright LEDs, some basic instrumentation and a video downlink that made it quite enjoyable to fly around with the good old "Fatshark" goggles.
Arduino Piezo Synth (7 Channel)
A very simple yet necessary stepping stone project on the way to the stepper motor synth. Using an Arduino Due, MIDI is streamed from my PC to the native USB port and played out of 7 passive piezo elements. See vid: https://youtu.be/gUxI7jJWoXg
RC Plane Autonomous Drone with Instumentation Video Downlink
This RC foam plane was converted into a autonomous flying platform with GPS, autopilot, IMU stabilisation, return to home, and a LOT of video-link overlayed instrumentation information. See the downlink video here: https://youtu.be/pNn0uFkRF2E
240-LED, Ultra-Bright 3-Channel Audio VU Meter
This module takes an audio signal, splits it into low, mid & high frequencies and then pulses 3 different sets of 10-segment bar graphs (each segment is 8 blue LEDs in series). With the other components included I had to solder 600+ total pins!
Linear Voltage Dropper Module (THE HEAT EJECTOR)
I needed to drop the voltage of various supplies in a simple and fun way. This device performs a adjustable fixed voltage drop of 0-25V at ludicrous currents. The massive heat sink and 10W fan allowed for 100W+ of dissipation (it's a hairdryer).
Zero-Bias Current Class-AB Audio Amplifier
A very old "relaxing" audio amplifier project with an input powered from +/-12VDC (SLA batteries). The audio signal is sent through an OPA2134 preamp and then to a BD135/BD136 power stage. With zero bias current, it relies entirely on feedback!
[WORK JOB] - Adding External PCIe Boards to an Embedded Computer (Stock Image)
Using Solidworks and a 3D printer I created a "slab" to sit below the computer that housed: Two PCIe boards, mini-to-PCIe converters/"risers", a fan/filter, a ventillator port, power entry (fan) & a modified computer hatch cover. Very tedious...
[WORK JOB] - USB-to-BNC 5V Trigger Box
With a USB/BNC I/O, this box switches the BNC output from 0V to 5V when the emergency stop button is pressed. Doing so also switches the LED indicator from red to green. Printed in 4 colours using the Prusa MK3S MMU2S, it simply looks beautiful!
[WORK JOB] - High Frequency Wireless Energy PCB (Stock Image)
This PCB is basically a custom wireless phone charger designed to power/communicate with another module. The micro utilised is the new Teensy 4.0 and the switching MOSFETs are PN: "RJK0855DPB". 80V, 30A, 11mohms & 10/20Vgs 35nC gate? Yes please!
[WORK JOB] - LED Pulser PCB
This PCB turns on a high speed LED as fast as practically possible. Using a fast MOSFET to charge the inductor current down one path, it can quickly divert that current through the LED path when needed. LR decay allows for a peak/cont. current.
[WORK JOB] - Hardware USB Interface Module
This module contians a PCB that interfaces a piece of legacy analogue hardware with the USB standard. The enclosure features 2 OLED LCDs, 3 LED buttons, a power switch, fuse holder, 3-state LED, 2 fans, 2 I/O row segments, 3 BNCs & a USB port.
[WORK JOB] - Deployable & Networked Rack Computer Nodes (Stock Image)
These nodes contain a computer supported by the necessary hardware to allowed ruggedised, reliable and rapid deployment for node to node networking with remote operation in mind. 32 system level I/O cables have been patched to the front panel!
[WORK JOB] - Network Wide Trigger System (Stock Image)
Need rugged I/O accross a network? These boxes will take an input logic state at any one node and replicate the state at all the other nodes via an ethernet port. Local signal in > Ethernet > Remote signals out. (Main PCB: Denkovi DAEnetIP3-ET)
Remotely Controlled Alarm: Buzzer Box 3000!
Using Fusion 360 for the two-part 3d-printed enclosure, this (electrically) simple project contains 8*AA batteries (12V), a DPDT on/off/on switch, a wireless relay module/remote, a LOUD two-tone piezo buzzer and a volume control potentiometer.
[WORK JOB] - Test Jig No.4
We developed a unit to test motherboard PCB assemblies semi-automatically through the use of test pins, relay boards, loads banks, LabJack DAQs & programmable power supplies. A PC running LabVIEW was used for interfacing & control.
Simplified Galileo's Pendulum Escapement
Based on Galileo's Pendulum Escapement, I designed a simplified mechanism that is suited to 3D printing. Several compromises were made in the name of simplicity, but overall I am very happy with the result! See here: https://youtu.be/OL7pxtfP1Ic
[WORK JOB] - Test Jig No.3
We developed two units to test the functionality of complete product assemblies. The tester checks wiring logic, device output voltages and harness impedances. All processes are controlled and logged via a µcontroller & PC terminal.
[WORK JOB] - Test Jig No.2
We developed a unit to test 5x5 arrays of panelised PCB assemblies. This tester contains test pins, relays, light sensors and light piping - All of which is duplicated 25 times and addressed via a µcontroller through demultiplexers.
[WORK JOB] - Test Jig No.1
Given existing test hardware and a complete assembly, I was tasked with creating a µcontroller control module for automation. Features/interactions include an RS-485 MODBUS line, a USB keyboard, an LCD screen and an SD card reader.
Fun Induction Motor Demo
A copper disc with three closely positioned 3-phase solenoids that induce a rotational torque in much the same way as the modern induction machine does. It is driven by a 12V, 3-phase inverter made of spare parts: http://youtu.be/ryu6BsR7XP0
150g Combat Robot for Adelaide Robot Combat (ARC)
A weapon-less pusher type, this 150g 3D printed robot is defined by its interchangeable armour, absurdly fast/powerful 15W motors, wide tyres and gyro stabilisation. A demo of the robot (gyro ON) can be seen at: https://youtu.be/QViHoi85h1A
PV Peltier Water Collector
Using 45 Watts of PV power (~18V MPP), two 30W Peltiers (0-9V), an MPPT buck converter (IV-matching) and a temperature switch (anti-frost), water is slowly collected at the cold-side heat sink where it falls through a funnel and into a bottle.
Breadboarded 80-LED Analogue Oscilloscope
A very old project. By using a single VU meter IC (LM3915?) and a another IC that sequentially connects the columns of LEDs to ground (i.e. the time scale), the VU meter effectively "sweeps" across the waveform in a quick succession.
Pulsed 800A Thyristor Solid State Switch
To control the discharge of my 50V/0.3F capacitor bank in a modular fashion I took an 800A peak thyristor, a piezo buzzer, a 9V battery and a momentary switch and then stuffed them all into an off the shelf project box with power I/O terminals.
Class-D Custom Bluetooth Speaker Unit (36W Max)
A 60W 12V plug pack power supply is boosted to 24V, which is then fed to a 50W class-D amplifier with bluetooth audio receiving capability. The output is then split at 3.8kHz with a 2nd order high & low pass filter for the 8Ω tweeter & woofer.
Peltier Freezer Ice Crystal Time Lapse
Two cascade Peltier units (top: adjusted to ~36W, bottom: ~72W) This draws about 9-10 amps total at 12V. Heat pump transfer is 15W optimally and the minimum cold side temp reaches -30°C. See: https://www.youtube.com/watch?v=s0KKzHtkc5o
128W Full-Bridge Class-D Audio Amplifier
32V & 4A input, 600kHz switching frequency and a soft start relay. These amplifiers are very hard to design but are very rewarding when they are done right. I would highly recommend them for anyone that wants to learn about power electronics.
Talking Animatronic Gundam Robot
Contains 6 servos, a text-to-speech unit, glowing eyes, audio reactive LEDs throughout, a spinning gun, power supply, audio amplifier, music, transformer, a brain and manual controls!
See it here: www.youtube.com/watch?v=E8185o7we04
180W Variable Linear Power Supply
A 1-30V, 6A linear power supply housing a TO-3 regulator, circuit and a serious heat sink. Features include: A soft start relay, a temperature-based two speed fan, under/over voltage alarms and disconnects, various displays & indicators + more!
MATLAB Code for 3D Printing Math Functions
I thought it would be a fun idea to visualise some math functions as 3D prints. The MATLAB script that I created took an equation, converted it to a surface plot, added a solid base underneath and generated an STL file for 3D printing.
PhD 4/4: Inverter H-Bridge Decentralised Cascaded System
I put together 4 control boards and 4 H-Bridge power stages to make a decentralised multilevel cascaded grid-tied inverter. The input is DC power which is converted and sent back to the grid. Effectively, this system educates and heats the room.
PhD 3/4: Bi-Directional Analogue/Digital 3.3V to 5V Converter
Now you think I would have realised that a serious H-bridge should be operable from 3.3V. Well I stuffed that up and as a result I needed a way to allow my 3.3V microcontrollers (Arduino Due) to interact with my 5V H-bridges and their sensors.
PhD 2/4: Inverter H-Bridge Power Stage V2.0
The final version of the H-bridge for the cascaded inverter of my PhD. This final version was much more robust, had a LOT of protection and other features that made controlling it so much simpler. To date, non of these boards have failed in use.
PhD 1/4: Inverter H-Bridge Power Stage V1.0
During the earlier stages of my PhD I realised I would need H-bridges for my cascaded inverter at a later point. I went about designing and constructing a very early version of the H-bridge to test. This was the first time I had used Altium.
Align Trex 550 Helicopter Assembly
The Align Trex 550 is a 1400W model helicopter with a body length of 1 metre and a battery life of 10 minutes. Assembling this allowed for a deep understanding of the mechanics of helicopter flight and maintenance. Very educational!
Prusa i3 3D Printer Assembly
To enter the world of 3D printing I purchased a Prusa i3 1.75mm from the official website and put it together. This was an exercise in mechanical assembly and greatly deepened my understanding of how 3D printers work.
Class AB Amplifier (Stereo 15W)
My first "serious" amplifier project! A dual 15W class AB amplifier with a bias current of about 1A per channel (that's a total standing heat dissipation heat of near 60W)! Summary: Dual Transformer-->Rectifiers -->Caps-->+/-15V-->Amp ALSO FAN!
FPV RC Car
A 200W remote control car with video/audio transmission. Features include a front/rear camera (with pan/tilt), front(10W)/rear(1W) headlights, rear microphone, 900MHz video with OSD, 2.4GHz control, and a fluffy doll for attracting children.
Room Automation Board
Using a micro-controller and the insides of a remote from a network of wireless mains relays, I automated the devices in my room. There is a motion sensor, a wireless "bedtime" switch and a set of pre-programmed configurations.
50V Capacitor Bank
A 50V capacitor bank made up of 10mF caps (31 of them). The total maximum energy is 387.5 joules. There is a controllable bleed resistor and voltage/current multimeters powered by a single 9V battery. The ultimate DC-link capacitor!
Projects I Like & Follow
Raphael Schaaf
Vishnu M Aiea
jean
Marius Taciuc
Vittorio Loschiavo
Carl Bugeja
ActualDragon
David H Haffner Sr
AVR (lordKiCAD)
Craig Hissett
davedarko
César
Josh Starnes
Andy Oliver
Nick SayerShare this profile
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David Scholten
wrote 03/20/2018 at 22:10
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There are a lot of great projects going on here for the Hackaday prize; they are all inspiring me to get some serious work done towards completing mine!
Yann Guidon / YGDES
wrote 03/20/2018 at 22:50
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Some more contest entries : https://hackaday.io/page/4768-buck-mating-season-2018 :-D
Vishnu M Aiea
wrote 03/20/2018 at 16:27
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Thanks for liking my project #EXPLOG : Exploration Logger You have a lot of cool stuff you've built. Great to see :)
Craig Hissett
wrote 03/19/2018 at 23:57
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Thanks for the like on my #Digibone project buddy.
Cheers!
ActualDragon
wrote 03/12/2018 at 04:04
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Thanks for the like on #DIY Box Goggles for Cheap FPV, stay tuned for updates!
Hi David, thanks for following https://hackaday.io/project/165458-350-watt-true-sine-inverter