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Videos uploaded by user “David Tsai”
Light-Dependent Resistor (LDR) Demo
 
02:16
I have my multimeter measuring the resistance of a light-dependent resistor (LDR) that changes resistance when light hits it. When no light hits the LDR, the resistance is greater than 60,000 Ohms. When light from my desk lamp hits the LDR, the resistance drops to about 3,000 Ohms. Also see my video on voltage dividing: http://youtu.be/rMjE60h3n3E
Views: 11997 David Tsai
Magic School Bus Theme for Clarinet Quartet
 
01:01
Instrumentation: three B flat soprano clarinets and one B flat bass clarinet.
Views: 1505 David Tsai
Linear Actuator Solenoid
 
02:44
I test out a 12V solenoid with a holding force of 4N. I created this video with the YouTube Video Editor (https://www.youtube.com/editor)
Views: 63474 David Tsai
Dividing a Quadrilateral
 
04:02
Have you even needed to split up an irregular (or regular) quadrilateral into x number of pieces with the same area? This tutorial shows you how. This is my first video tutorial where I actually speak, so please excuse a few stutters here and there.
Views: 1175 David Tsai
How to Rewind a VHS with a VHS Rewinder
 
02:42
VHS is going to disappear eventually, so let's take a moment to appreciate the humble process of rewinding a tape.
Views: 1419 David Tsai
L Train Doesn't Need Operator?
 
01:16
This was taken from the Manhattan-bound platform at the Lorimer Street station on the BMT Canarsie Line. If you look closely at the video, you'll see that the operator isn't touching the dead man's switch on the power/brake lever. When the train pulls away, the lever is still in its full braking position; all that the operator does is press a button. This suggests that the train is controlling braking and accelerating by itself.
Views: 57714 David Tsai
Canon Speedlite 540EZ with Bench Supply
 
03:22
This is just an experiment! I stick alligator clips into the battery compartment of the Canon Speedlite 540EZ flash unit to see how much power it uses when it's off, when it's on but idle, and when it's charging up.
Views: 2001 David Tsai
Q Train Heads toward Second Avenue Subway Part 1
 
01:45
This was shot in the 57 St.-7 Av. subway station. A train of R160 cars, which were signed as not in service, pulled into the southbound express tracks from the south. They stayed there for about two minutes before heading toward the Second Avenue Subway (https://www.youtube.com/watch?v=ciI78-8XNTo).
Views: 3455 David Tsai
Voltage Divider (with LDR)
 
04:22
Two resistors in series act as one resistor with a resistance that is the total of the resistances of the two resistors. According to the loop rule, the voltage rises and drops in a circuit must add up to zero. Regardless of the resistances of the resistors, they will drop five volts because the supply supplies five volts. When there are two or more resistors, you can measure their individual voltage drops. They should add up to the supply voltage, which is five volts in this case. In the video, I use a light-dependent resistor (LDR) and a regular resistor. When light hits the LDR, its resistance changes, which causes the voltage drops across the two resistors to change. However, the voltage drops will always add up to the supply voltage. Sensing LDR voltage on an Arduino microcontroller: http://youtu.be/xVf0cdZDdWs LDR demo: http://youtu.be/j4QQuCMG14w What causes a resistor to smoke? Peer pressure.
Views: 757 David Tsai
Bicycle Generator Part 3 - Testing a 6W Dynamo
 
03:31
I decided to use a dynamo designed for headlights to generate my electricity. I tested it on my bicycle in my garage and discovered that it generated AC instead of DC. Now, I will need to rectify that current.
Views: 1503 David Tsai
Enable and Disable Device from Shortcut on Desktop
 
16:51
Windows 7 and 8: Enable and disable devices through two little shortcuts on the desktop instead of having to go through the Device Manager.
Views: 7832 David Tsai
Wiring Canon SpeedLite for External DC Power
 
03:25
I add two small wires to my Canon SpeedLite 540EZ so that I can easily hook it up to my bench power supply. I created this video with the YouTube Video Editor (http://www.youtube.com/editor)
Views: 2280 David Tsai
Jamaica-Bound J Train Switching Tracks North of Chambers Street
 
02:33
When heading north out of Chambers Street, the J train always switches over two tracks to the left. You can see this right after the train leaves Chambers Street, the first station in the video. Right before the train gets to Canal Street, the second station in the video, you can also see some diverging track to the right that goes to the unused east platform at Canal Street.
Views: 293 David Tsai
Microwave Oven and Kill-a-Watt
 
01:22
This microwave oven uses 2000 watts at full power, which I measured with a Kill-A-Watt.
Views: 264 David Tsai
Korg CA-1 Chromatic Tuner on DC Power Supply
 
02:31
I took the batteries out of an old Korg CA-1 Chromatic Tuner that I had. In their place, I put a DC power supply. Now, I can see how much power the device uses.
Views: 934 David Tsai
Brittany Hall's Penthouse Lounge was a Speakeasy
 
03:16
I briefly tour of the Penthouse Lounge on the 17th floor of New York University's Brittany Residence Hall in New York, New York. Before NYU acquired the building, it was the Brittany Hotel. During Prohibition, this room served as a speakeasy, where people could get their hands on alcoholic beverages illegally.
Views: 260 David Tsai
Qualcomm Quick Charge 2.0 in the LG G4
 
01:41
Here's an old video that I never uploaded before. I plugged my phone in at 6:06 PM at 31%. In the video, you can see that the phone reached 41% at 6:08 PM. The USB meter shows 9 volts at 1.2 amps, which is more than 10 watts.
Views: 2985 David Tsai
Automatic Lights - Arduino with WeMo Demo
 
03:17
Here's the final result of my testing. When I enter the room, the lights turn on. When I exit the room, the lights turn off.
Views: 1079 David Tsai
Quick Tip - Magnetize a Screwdriver
 
00:43
You can magnetize a screwdriver by putting a small magnet on it. Another trick is to run the magnet along the shaft a few times.
Views: 590 David Tsai
Misusing the Mic Check in SmartMusic
 
01:27
MakeMusic's SmartMusic software has a wizard that automatically calibrates the recording level of your microphone. However, it doesn't listen for the pitch that it asks you to play.
Views: 565 David Tsai
Treadmill Generator?
 
01:28
There's a motor inside this treadmill, but motors can act as generators and turn motion into electricity. I put my multimeter on the spades and did a little test.
Views: 1209 David Tsai
R142A 6 Express Automated Announcement
 
01:47
Most 6 trains were still served by R62 cars, and the few that are served by R142 and R142A cars don't often run express in the Bronx. This one did, so I was able to record the automated station announcements.
Views: 1438 David Tsai
Testing the L298N Chip on a Board
 
02:35
I received a new circuit board with the L298N motor controller chip. This is a dual H-bridge configuration; the chip can drive two motors each in two directions. The board has simple input pins that can be controlled with a voltage signal, including that out of an Arduino or Raspberry Pi. I will be connecting the motor controller to a Raspberry Pi in another video soon.
Views: 2587 David Tsai
Sightreading in SmartMusic
 
09:13
I demonstrate two sightreading exercises in SmartMusic, an application from the makers of the Finale music notation program designed to help music students practice. I am a member of my high school band in New Jersey, and I have played the clarinet for ten months now after switching from the flute. Recently, I also picked up the tenor saxophone to join jazz band. My website: http://davidtsai.net63.net/ (changed since I made the video)
Views: 5791 David Tsai
Bicycle Generator Part 4 - It Works!
 
02:55
I charge my iPod with the system that I have set up on my bicycle. In this video, I put together the dynamo, the rectifier, and a voltage regulator to generate electric current from the spinning wheel on my bicycle.
Views: 461 David Tsai
DIY Audio Connector Adapter: 3.5mm analog to Red/White (a.k.a. TRS to RCA)
 
07:17
The basic principle in this video is that electricity is electricity; it will flow through conductors regardless of their shapes. I wanted to play music from my iPod Shuffle through a stereo system that only accepted RCA inputs but didn't have an adapter handy, so I had to make one with aluminum foil and spare wires. This will also work with any source device that outputs sound through 3.5mm analog audio, including most computers, smartphones, tablets, and other iPods, not just the iPod Shuffle. No wire cutters are needed.
Views: 325820 David Tsai
Capacitors in My Bicycle Generator Schematic
 
07:45
I use circuit simulation software to illustrate an idea that I have for my bicycle generator. The initial power supplied by the generator as it's spinning up is very low, and my Nexus 7 detects that low power level and does not draw more power, even as the generator reaches full speed. My proposed solution is to add some capacitors in parallel with the voltage regulator. The capacitors will supply power to the tablet as the generator is spinning up, and the tablet will charge at full power before and after the generator takes over. You can use the circuit simulator yourself here: http://falstad.com/circuit/index.html
Views: 132 David Tsai
Electromagnetic Door Lock
 
03:23
I acquired a direct pull magnetic lock, and I wanted to show how it works. I created this video with the YouTube Video Editor (http://www.youtube.com/editor)
Views: 434 David Tsai
E Train on 8th Av Express
 
01:55
This FIND display on an R160 subway car was programmed to show the E train not skipping stops but just running express. The train did actually move physically to the express track north of 42nd St-PABT. However, the E train usually would say that it was the 8th Av Local and skipping 23rd St and Spring St.
Views: 909 David Tsai
Installing UserScript in Google Chrome
 
04:04
A recent update to Google Chrome has made installing userscripts difficult. This video shows a workaround using my Facebook Automatic Poke Returner. My website: http://davidtsai.net63.net/
Views: 5907 David Tsai
Stairway to Heaven Guitar Solo Transcription for Flute - Part 3
 
01:15
I'm transcribing Jimmy Page's solo from Led Zeppelin's Stairway to Heaven for the flute. This version includes the piano accompaniment and drum kit part.
Views: 2464 David Tsai
I Called the USNO
 
04:05
I found the telephone number for the Master Clock online, so I decided to call it. You can also see me hold up my SkyScan alarm clock, which is synchronized to the same atomic clock.
Views: 1913 David Tsai
Light-Dependent Resistor (LDR) on DC Power Supply
 
01:05
Now, I use a light-dependent resistor (LDR) as the load on a DC power supply.
Views: 111 David Tsai
Use Tin Snips to Open Plastic Packaging
 
01:07
I sometimes think that I'm destroying a good pair of scissors when I cut this kind of plastic packaging open. Well, I'm just going to use tin snips from now on.
Views: 419 David Tsai
F Train on Culver Express
 
01:22
On May 16-20 11:15 PM to 5 AM, F trains ran express between Church Avenue and Jay Street-MetroTech due to construction.
Views: 322 David Tsai
Time Lapse: Mail from Colleges
 
03:02
I take the mail that colleges have sent me over the last year or so and pile it all up. Weighing the mail: http://youtu.be/KugL2ntVxIg Music Provided by NoCopyrightSounds: Alan Walker - Force: https://youtu.be/xshEZzpS4CQ
Views: 899 David Tsai
Luggery
 
01:33
I should get puppets.
Views: 38 David Tsai
Takeoff from Runway 2 at Richmond International (KRIC)
 
03:00
Aircraft: ERJ-140 Seat: 15C Tail number: N849AE
Views: 56 David Tsai
Rotating PDF in Browser
 
04:52
I quickly rotate a PDF document in Google Chrome and in Internet Explorer
Views: 3845 David Tsai
J Train Uses Eastbound Track at Essex Street
 
01:59
On weekends, the M train short-turns at Essex Street on the middle track. The J train uses the eastbound track to get on the Williamsburg Bridge. On weekdays, eastbound J trains arrive on the middle track, which comes straight from Bowery. However, in order to get onto the eastbound track, an eastbound J train switches tracks twice after leaving Bowery. This video captures those track switches. You can see a four-car M train in the far left at 1:21.
Views: 62 David Tsai
1 Train Dispatch from South Ferry
 
01:16
A 1 train departs from the reopened South Ferry station.
Views: 81 David Tsai
Voltage Dividing LDR with Arduino
 
05:17
I use an Arduino Uno microcontroller to get a voltage reading off of a light-dependent resistor (LDR). See my other video on using an LDR to divide voltage: Voltage Dividing: https://youtu.be/rMjE60h3n3E LDR demo: http://youtu.be/j4QQuCMG14w
Views: 359 David Tsai
Clickjacking Demonstration
 
02:47
Some malicious websites try to do things that trigger security warnings in your browser. Unfortunately, when the security warnings don't appear outside of the page, the website could manipulate the security warning and trick you into authenticating the actions. This is a demonstration of how the stuff works.
Views: 2406 David Tsai
Bicycle Generator Part 1 - Voltage Display
 
02:36
I have been in the process of fitting a DC generator to the back wheel of my bicycle. Here is YouTube's first look at it. So far, all that I have wired up is a cheap digital voltage display that I found on eBay. Part 2: http://youtu.be/IuOqnkmLLMc
Views: 157 David Tsai
Belkin WeMo Problems
 
01:02
The WeMo app can't connect to the light switch.
Views: 10799 David Tsai
Sorting PowerSchool Schedule by Period
 
05:29
By default, PowerSchool sorts your schedule by Course Name. However, that's not really useful when you try to follow the schedule by Period. This video shows you how to sort your schedule by any column you want and also clean the layout in PowerSchool up to make it more presentable. The webpage with the second snippet of code: https://github.com/padolsey/jQuery-Plugins/blob/master/sortElements/jquery.sortElements.js YouTube won't let me paste JavaScript code in here, so go to http://pastebin.com/iNM3n99L for the three snippets of code besides the one above.
Views: 612 David Tsai
Counting Stars Using Software
 
06:39
My computer counts objects for me. This demonstration uses paper stars that Emily Yao and I are folding for a friend. ImageJ: http://rsbweb.nih.gov/ij/
Views: 84 David Tsai
Temperatures of Stuff while Cooking
 
04:33
I shot this a while ago but didn't think to upload it to YouTube until now. I was simply filming while cooking. I like to use my thermometer while cooking because it lets me know how far things have heated up. I created this video with the YouTube Video Editor (http://www.youtube.com/editor)
Views: 27 David Tsai
Stairway to Heaven Guitar Solo Transcription for Flute - Part 1
 
00:23
The entire solo is here: http://youtu.be/jidn0CNX-XA I'm transcribing Jimmy Page's solo from Led Zeppelin's Stairway to Heaven for the flute. For now, I only put the basic chords in the accompanying piano; I'll transcribe the other voices in the music later. These are the first eight bars of the guitar solo.
Views: 1724 David Tsai