A Clock Timebase, No Microcontroller

April 17, 2023 by Jenny List 20 Comments

Making an electronic clock is pretty easy here in 2023, with a microcontroller capable of delivering as many quartz-disciplined pulses as you’d like available for pennies. But how did engineers generate a timebase back in the old days, and how would you do it today? It’s a question [bicyclesonthemoon] is answering, with a driver for a former railway station clock.

The clock has a mechanism that expects pulses every minute, a +24V pulse on even minutes, and a -24V pulse on odd ones. He received a driver module with it, but for his own reasons wanted a controller without a microcontroller. He also wanted the timebase to be derived from the mains frequency. The result is a delve back into 1970s technology, and the type of project that’s now a pretty rare sight. Using a mixture of 4000 series logic and a few of the ubiquitous 555s [bicyclesonthemoon] recovers 50Hz pulses from the AC, and divides them down to 1 pulse per minute, before splitting into odd and even minutes to drive a pair of relays which in turn drive the clock. We like it, a lot.

Mains-locked clocks are less common than they used to be, but they’re still a thing. Do you still wake up to one?

A CMOS Ring Modulator Pedal

December 24, 2021 by Jenny List 9 Comments

Earlier this year, we featured an unusual radio receiver that took the very traditional superhetrodyne design and implemented it in an unexpected fashion without any inductors, using instead a combination of 74HC logic chips and op-amps. Its designer [acidbourbon] remarks that the circuit bears a striking resemblance to a ring modulator,so has taken it down that path by producing a 74HC based ring modulator guitar pedal.

In both circuits, a 74HC4046 phase-locked loop chip serves as an oscillator, driving a 74HC4051 analogue switch chip that performs the mixer task. The extra-op-amp filter and demodulator circuitry from the radio is omitted, and the oscillator frequency moved down to the audio range. The result can be heard in the video, and we probably agree with him that it’s not quite the same as a classic ring modulator. This lies in the type of mixer, the diodes used in a traditional circuit have a forward voltage to overcome before they start or end conducting, while the CMOS switch chip does so immediately on command.

The 4000 series CMOS and their descendants are a fascinating family with many unexpected properties that our colleague Elliot Williams has gone into detail with for his Logic Noise series. Meanwhile take a look at our coverage of the original radio.

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Friday Hack Chat: Logic Noise

May 30, 2018 by Elliot Williams 2 Comments

If you like your synthesizers glitchy, squawky, or simply quick-and-dirty, you won’t want to miss this week’s Hack Chat with Hackaday’s own [Elliot Williams], because he’ll be brain-dumping everything he knows about making music with 4000-series CMOS logic chips. Break out your breadboards!

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An 8-Bit ALU, Entirely From NAND Gates

March 31, 2018 by Jenny List 18 Comments

One of the things that every student of digital electronics learns, is that every single logic function can be made from a combination of NAND gates. But nobody is foolhardy enough to give it a try, after all that would require a truly huge number of gates!

Someone evidently forgot to tell [Notbookies], for he has made a complete 8-bit ALU using only 4011B quad NAND gates on a set of breadboards, and in doing so has created a minor masterpiece with his wiring. It’s inspired by a series of videos from [Ben Eater] describing the construction of a computer with the so-called SAP (Simple As Possible) architecture. The 48 4011B DIP packages sit upon 8 standard breadboards, with an extra one for a set of DIP switches and LEDs, and a set of power busbar breadboards up their sides. He leaves us with the advice borne of bitter experience: “Unless your goal is building a NAND-only computer, pick the best IC for the job“.

We have covered countless processors and processor components manufactured from discrete logic chips over the years, though this makes them no less impressive a feat. The NedoNAND has been a recent example, a modular PCB-based design. TTL and CMOS logic chips made their debut over 50 years ago so you might expect there to be nothing new from that direction, however we expect this to be well of projects that will keep flowing for may years more.

Via /r/electronics/.

Logic Noise: More CMOS Cowbell!

April 10, 2015 by Elliot Williams 23 Comments

Logic Noise is an exploration of building raw synthesizers with CMOS logic chips. This session, we’ll tackle things like bells, gongs, cymbals and yes, cowbells that have a high degree of non-harmonically related content in them.

Metallic Sounds: The XOR

I use the term “Non-harmonic” in the sense that the frequencies that compose the sound aren’t even integer multiples of some fundamental pitch as is the case with a guitar string or even our square waves. To make these metallic sounds, we’re going to need to mess things up a little bit, and the logic function we’re introducing today to do it is the exclusive-or (XOR).

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Hacklet #8: The Animals

July 25, 2014 by Adam Fabio 8 Comments

This week on the Hacklet we’re looking at Hackaday.io projects that are all about animals! Hackers and makers are well-known animal lovers, in fact many a hacker can be found with a pet curled up at their feet, or on their keyboard!

[Brian’s] cat Roger loves drinking from the bathtub faucet. Unfortunately Roger hasn’t learned how to operate the faucet himself, so it gets left on quite a bit. To keep Roger happy while saving water, [Brian] created the Snooty Cat Waterer. Cat’s still don’t have thumbs, so [Brian] turned to capacitive sensing in the form of a Microchip MTCH10 capacitive proximity sensor chip. Coupled with a home etched PC board, the waterer can detect a cat at 3 inches. A valve and water feed teed off the toilet provide the flow. The project is moving along well, though Roger has been slow to warm up to this new water source.

[Jsc] has the opposite problem. His cat has decided that bathtubs are the perfect litter boxes. [Jsc] is taking aim at this little problem with his Cat Dissuader. After a servo controlled squirt bottle proved too anemic for his needs, [Jsc] turned to the Super Soaker Hydrostorm. These electric water guns can be had for as little as $16 on sale. [JSC] didn’t want to permanently modify the gun, so he 3D printed a switchable battery pack.The replacement pack is actually powered by a simple wall wart. Power to the gun is controlled by an Arduino, which senses his cat with a passive infrared sensor. Since the dissuader was installed, [Jsc’s] cat has been a model citizen!

Cat’s don’t get all the love though, plenty of engineers and hackers have dogs around the house. [Colin] loves his dog, but he and his family were forgetting to feed it. He created Feed the Dog to help the household keep its four-legged member from going hungry. [Colin] tried a microcontroller, but eventually settled on implementing the circuit with old-fashioned 4000 series CMOS logic chips. He used a 4060 (14-stage ripple counter w/ internal oscillator) as an 8 hour timer, and 4013 dual flip-flop. Operation of Feed the Dog is as simple as wagging your tail. Once the dog is feed, the human presses a button. A green “Just fed” LED will glow for 30 minutes, then go dark. After about 6 hours, a red LED turns on. After 8 hours, the red LED starts blinking, letting everyone know that it’s time to feed the dog.

[Steve] has outdoor pets. Chooks to be exact, or chickens for the non Australians out there. He loves watching his birds, especially Darth Vader, who is practicing to become a rooster. To keep track of the birds, he’s created What the Chook?, a sensor suite for the hen-house. He’s using a GCDuiNode with a number of sensors. Temperature, humidity, even a methane detector for when the bedding needs to be replaced. An OV528 JPEG camera allows [Steve] to get pictures of his flock. The entire project connects via WiFi. Steve hopes to power it from a couple of AA batteries. [Steve] also entered What the Chook? in The Hackaday Prize. If he wins, this will be the first case of flightless birds sending a human to space!

Hey – Did you know that Hackaday is building a Hackerspace in Pasadena California? We’re rounding up the local community while our space is being built out. Join us at a Happy Hour Show & Tell Meetup Event hosted by our own [Jasmine Brackett] August 18th! It’s an informal show and tell, so you don’t have to bring a hack to attend. If you’re local to Pasadena, come on down and say hello!