Pure TTL Based Clock

March 16, 2010 by Jakob Griffith 28 Comments

We’ll just say, [Kenneth] really likes clocks. His most recent is a pure 7400 series TTL based one, ie no microcontroller as seen in the past, here, here, and here. The signal starts out as a typical 32,768 crystal divided down to the necessary 1Hz, which is then divided again appropriately to provide hours and minutes.

As far as TTL clocks go, this is nothing too original; until it comes to his creative button interface. By using a not as sexy as it sounds multivibrator, he can produce a clean square wave instead of the figity signals produced from buttons to advance and set the time. Like always, he also provides us with a thorough breakdown of his clock, after the jump. Continue reading “Pure TTL Based Clock” →

Use An Analog Oscilloscope To Display Digital Logic

February 11, 2010 by Mike Szczys 31 Comments

[Mike Bradley] wanted to use his oscilloscope to display 8 channels of digital signals. Alas, the analog unit didn’t have this capability. Not to worry, he threw together an adapter module that does the trick. Using a PIC 18F26K20 microcontroller he inputs four or eight channel digital logic (at 5V) and filters the output to an analog signal that the oscilloscope can interpret. What you see in the photo above is the result.

Arduino Traffic Light

January 5, 2010 by Mike Szczys 28 Comments

[Rockwell] sent us an update on his traffic light hacking. Dedicated readers will remember seeing this legally attained traffic signal controlled through a parallel port from back in 2005. The new update swaps the old port for USB and adds several autonomous functions which are demonstrated in the clip after the break. The update includes a nice UI and some notifications for things like email, IMs, Reddit posts, etc.

He’s given control of the hardware over to an Arduino. Instead of building the board into the project he’s included just the parts he needs; an AVR running the Arduino bootloader, a crystal and filtering caps, and an Arduino serial to USB module for connectivity. The AC load switching is handled by three relays. The relays he links to are 12VCD rated coils. We think this should have pointed to 5VDC coils as that’s the voltage that the logic circuit are running at. Be careful with switching these AC loads, this traffic light isn’t a toy.

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Trailer Side Indicator Lights

December 31, 2009 by Mike Szczys 29 Comments

[Imsolidstate] is working to add side turn signals to a trailer. These orange clearance lights are illuminated when the vehicle’s headlights are on to increase a long trailer’s visibility. They also blink along with the turn signals on the back of the trailer. A standard 6-pin lighting harness doesn’t support this functionality so the trick is to add them without altering the towing vehicle in any way. He’s using an ATtiny24 microprocessor to interpret the logic from the vehicle and then translate the turn signal and tail light data into a signal for the additional side indicators.

McLVDT: A Straw-based Sensor

December 1, 2009 by Mike Szczys 13 Comments

We saw [Kevin’s] home-built Linear Variable Differential Transformer in a YouTube video last week and wanted to know more. We’re in luck, he agreed to share all the details as well as a bunch of information on these sensors. An LVDT is used to measure distance along a straight path. Unlike a linear optical encoder, this method uses measurements of inductance between two electrical coils to judge the distance.

[Kevin] used some magnet wire wrapped around two straws of different diameter to fabricate his sensor. A signal generator is connected to the primary coil and the resulting signal induced in the secondary coil is measured to reveal the change in physical position. Check out the video after the break to see the results.

It’s not hard to get your hands on a McDonald’s straw (hence the name ‘Mc’LVDT), a smaller inner straw, and a few feet of magnet wire. This will be a fun one to try when those dark winter days start to get to you.

Continue reading “McLVDT: A Straw-based Sensor” →