Author Archives: DP

Do you need an incubator for hatching eggs?  T0mpr1c3 shows you how to easily make a homemade egg incubator: This is a project from a couple years ago, which I published on the members’ pages at the Backyard Chickens forum: An automatic egg incubator with PID temperature control and periodic egg-roller, built into a microwave […]

Check out Jussi’s 7400 contest entry, the polonaise machine. It’s a sound generator with the Telemann’s Polonaise tune incorporated into the design. After about half an hour of brainstorming I came up with the idea of a modern musical box. In a few moments I had the core of the machine ready on a paper […]

Class D amplifier using digital logic is the open 7400 competition entry by hasn0life: The entry is a class D amplifier made entirely out of discrete digital logic components. I took great pains not to use op amps or transistors or any active devices besides logic gates. Though the amplifier outputs square waves, the process […]

It’s time to Press Your Luck! Check out Christopher’s nixie-based Press Your Luck game for the Open 7400 Logic Competition : Press Your Luck (tv game show) in Nixie form, getting a W (view the tube upsidedown) is like getting a Whammy. See how many points (other cathodes) you can get before hitting 3 whammies. […]

Here’s a 6 digit frequency counter by Yi, entered into the Open 7400 Competition. During the Winter break my dentist convinced me that I needed to have my 2nd wisdom teeth removed. Having done this previously without much pain, I thought it would be a good idea. It turned out to be much more involved […]

Nakul Rao I, Nischal Rao, Nikilesh, and Sandesh VS entered a bicycle exercise meter and burger alarm into the Open 7400 Competition. Their project keeps track of your bicycle’s speed, cadence, and distance while you’re exercising. It also acts as a burglar alarm when you’re away. This is something we had done about an year […]

Don’t wanna lose your car? Build a CMOS 4000 series car alarm and enter it in the open 7400 competition. Built way back in the 1980s this CMOS Car Alarm provided an entry & exit alarm for my wonderful little Mini. It was built from CMOS series logic to reduce the current consumption and the circuit […]

Here’s an interesting way of designing analog devices using digital chips. This sine wave generator s based around mosfets contained in the CD4007 IC (a dual complementary pair of mosfets and an inverter). The CD4007 dual complementary pair and inverter is primarily intended for digital logic circuits. It contains an inverter, and two pair of PMOS and […]

Jvok’s open 7400 Logic Competition entry is the CD4000 digital alarm clock. As the name suggests this is an alarm clock based on CMOS 4000 series logic ICs. I designed this clock over the course of two weeks for the Open 7400 Competition. The clock, which is made from 25 CD4000 ICs, three 555/556 ICs and […]

Here’s another 7400 entry, BrainF**k machine. This is a home brew 8bit CPU with 8 instructions, supporting the BrainF**k esoteric programing language. It is possible to design a relatively powerful processor with a very small amount of logic circuitry, provided that the architecture and the instructions are carefully built for a concrete application. 74 logic […]

Control your lights via a 7400 based dimmer. This is RodLophus’ entry for the open 7400 Logic Competition: The idea is: For a typical dimmer, when you apply a pulse on the gate terminal of the TRIAC, it turns on – and stays on until the mains voltage crosses the 0V. So, varying the “firing angle” […]

Here’s David’s 7400 entry, the Mr. @#?%!…A 74xx based Q*Bert-ese obscenity generator: In honor of the 30th anniversary of Q*Bert’s release in arcades, I present “Mr. @#?%!”… A 74xx-based Q*Bert-ese Obscenity Generator, built exclusively using parts available in 1982. Build something that uses or abuses a logic chip and get amazing boards, tools, and other […]