7400 competition entry: Drum machine

Christopher created a Drum Machine for the Open 7400 Logic Competition. He also documented it in a video below.

The idea for building a drum machine came from a discussion I had with my roommates in which we were talking about the popularity of drum machines as simple web applications. I decided to try to implement one, but using 7400 Logic Chips. The design was rather simple and is based mostly around utilizing sequential logic devices in order to count, step through and play different tones.

Via the contact form.

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7400 competition entry: Accelerometer controlled racing game

Juan entered an Accelerometer controlled racing game into the Open 7400 Logic Competition. Check out the video of the gameplay below.

My project is a simple video game in which you control a car and have to move it sideways in order to avoid obstacles.

Via the contact form.

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7400 competition entry: CD4007-based voice changer

Reymond entered a CD4007-Based Voice Changer into the Open 7400 Logic Competition:

The project uses 2 – CD4007 configured as a Gilbert Cell Double Balanced Modulator and an additional 2 – CD4007 for use as a difference amplifier. This kind of effect is known as a Ring Modulator in the audio community…

Via the contact form.

7400 competition entry: Capacitance meter

Alvaro built a Capacitance meter out of logic chips for the Open 7400 Logic Competition. His project measures capacitance of a capacitor and displays it on a 7-segment display.

It works by using the said capacitor in a RC oscillator, which changes its output frequency proportionally to the capacitance in it’s RC circuit. The frequency is then measured by comparison to a known stable clock. The video above shows it in action.

Via the contact form.

Free PCB coupon via Facebook to 2 random commenters


Every Friday we give away some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes to two random commenters. More PCBs via Twitter on Tuesday and the blog every Sunday.

Don’t forget there’s free PCBs three times a every week:

  • Free PCB Sunday. The classic. Every week, get free PCBs right here on the blog comments
  • Tweet-a-PCB Tuesday. Follow us and get boards in 144 characters or less
  • Facebook PCB Friday. Free PCBs while you wait for the weekend

Get your own handy Bus Pirate for $30, including world-wide shipping. Also available from our friendly distributors.

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7400 competition entry: Peltier temperature controller

Michael entered a TEC temperature controller into the Open 7400 Logic Competition. Logic chips control the temperature of a thermoelectric Peltier element (TEC) heating/cooling plate.

Current temperature is measured via a sensor placed directly on the Peltier. The target temperature is set by an 8bit dip-switch. The circuit will cool or heat the Peltier until the goal temperature is met. Check out the circuit in action below.

Via the contact form.

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7400 competition entry: LED clock

Michael built an LED clock for the Open 7400 Logic Competition. He added 60 LEDs to an analog clock which are controlled by discrete logic chips.

This project uses a standard analog quartz clock and adds 60 LEDs clockwise around it to display the seconds.

There are 2 selectable modes via 2 jumpers:

Mode 1: Every second, each LED is activated one after another. After 1 minute, all LEDs are on. Then every second each LED is deactivated one after another. After 1 minute, all LEDs are off. This is continuosly repeated, so the seconds are visualized by LEDs. This mode uses an integrated 1 Hz timebase and loop-back mode of the shift registers. For this mode, jumpers JP1 and JP2 both need to be connected to positions 1-2 (see schematic).

Mode 2: All 60 LEDs can be controlled externally, for example by a microcontroller or by a PC. Thereby you have full control of the displayed LED patterns. In this mode, the signals /CLEAR, CLK and DATA of the 74164 chain have to be controlled externally via connector J1. For this mode, jumpers JP1 and JP2 both need to be connected to positions 2-3 (see schematic). .

Via the contact form.

Check out the video of it below. Continue reading “7400 competition entry: LED clock”

7400 competition entry: AM radio transmitter

Andrew entered an AM radio transmitter into the Open 7400 Logic Competition:

My 7400 contest entry is an AM Radio Transmitter, which nicely complements another entry. The TX frequency is digitally tunable from 520kHz – 1.6MHz, although this part of the circuit is open loop, so tuning to a specific frequency may require a slight adjustment on a potentiometer. The RF section is strong enough to broadcast across a room, but weak enough that it shouldn’t interfere with anything important. Here is a screen shot of a 1kHz audio signal on a 930 kHz (approx) carrier. Full circuit information, including the theory of operation, is outlined on my website.

Via the forum.

Check out the video of his entry below. Continue reading “7400 competition entry: AM radio transmitter”

7400 competition entry: Beeping down counter

Chris decided to enter another project into the Open 7400 Logic Competition. The beeping down counter, as it’s name suggests, is a pre-settable timer which beeps and uses a display to show the seconds left on the timer.

The goal of this project is to duplicate the down counting circuit used by the character Ivan Vanko in Iron Man 2 to aid his escape from prison in Manaco. There are three key components that go into this design:

     

  • A Down Counter With Dual 7 Segment LEDs
  • A Push Button To Initiate The Down Counting
  • A Quick ‘Beep’ Sound With Each Down Count

Via the contact form.

He also filmed a video of his project which is shown below.

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7400 competition entry: FM modulation and demodulation system

Alifred and his friend entered a FM modulation, demodulation and transmission system into the Open 7400 Logic Competition.

An input waveform enters the Voltage Controlled Oscillator (VCO), resulting in a FM modulated waveform. This is then sent to an IR LED (through a buffering MOSFET) and is received by a photo-transistor at the other end. The output signal from a photo-transistor resistor network is then fed through a Schmitt trigger to clean the waveform. The signal is then demodulated by using it to trigger a short-pulsed monostable. This results in a charge build up on the end capacitor which is proportional to the trigger frequency, thus recovering the original waveform.

Check out a 1min time-lapse video of their ~8h project development process below.

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7400 competition entry: Discrete logic amplifier

Haley0918 added another entry to the Open 7400 Logic competition:  Discrete logic amplifier:

This is my second entry for the 7400 logic competition. It’s a discrete logic amplifier made of mostly discrete logic chips. This amplifier is a continuation of my previous discrete logic preamp. The main objective here is to amplify the input signal to a suitable level for driving a buzzer or other voltage driven application.

You can check out his project in action below.

Via the contact form.

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7400 competition entry: Digital die (74XX Family)

Sean Breen entered his Digital die (74XX Family) into the Open 7400 Logic Competition:

Here is a rather simple but practical use for digital electronics…..dice! (or in the case a single die)

Unlike many of the kits found online this one does not use a micro controller. The entire circuit is based around 74LSxx logic ICs and a 555 timer for a clock.

Via the contact form.

Check out the video of this entry below.

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7400 competition entry: TTL based range finder

Udif entered the TTL based range finder into the Open 7400 Logic Competition. It uses an ultrasonic sensor to determine the distance to an object.

The sensor outputs a pulse, the width of the pulse is proportionate to the distance measured. The sensor signal drives a clock which in return increments a counter. The clock is timed so that each tick of the counter responds to 1cm of distance, and the output is shown on a 7-segment display.

Via the forum.

7400 competition entry: TimeBonder 275

Sigitronic built the TimeBonder 275 and entered it into the Open 7400 Logic Competition. It is a versatile timer that uses the mains frequency as the clock signal, both 50Hz and 60Hz are supported.  It can time events ranging from 100ms to 99.9s with a resolution of 100ms, or up to 999s with a resolution of 1s.

Via the forum.

7400 competition entry: AM radio

Jason entered his AM radio into the Open 7400 Logic Competition:

One unusual use for a logic chip is as an analog amplifier. Most logic with inverting outputs can be used this way. In order to demonstrate this functionality, I’ve built an AM radio with a 74HCU04 inverter. The inverters are used both as RF amplifiers and as audio amplifiers. It is capable of tuning any frequency all the way from VLF through HF if you change the values of the components in the tuned circuit, but I’ve built it to cover the AM broadcast band (540kHz through 1600kHz in North America).

Via the forum.

7400 competition entry: Discrete logic preamp

Haley0918 entered his Discrete logic preamplifier into the Open 7400 Logic Competition.

Through some experimentation he figured out that a XOR gate shows some analog properties. By modulating the input between 0.8v and 1.2v the output was swinging between 1v-4v, making the logic IC a preamplifier with a gain of 7.5. You can check out his circuit in action below.

Via the forum.

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7400 Competition deadline has passed

The Open 7400 Competition deadline (October 21, 6am GMT) has passed. Today we will dedicate the blog to the numerous last minute entries.  Normal posting will resume tomorrow.

On behalf of the 7400 Competition sponsors, and the Dangerous Prototypes crew, we thank you for taking the time to enter the competition.

Sponsors of the Open 7400 Competition

Logos Electromechanical LLC

The Gadget factory

7400 competition entry: Police lights and siren for a toy car

Nathan entered his Police lights and siren for toy car into the Open 7400 Logic Competition:

A Little Tikes Patrol Police Car was retrofitted with a battery-powered emergency police lights and siren system as an entry to the Dangerous Prototypes Open 7400 Logic Competition. The circuit design focuses on simplicity and efficiency of part utilization by using only two 7400 series integrated circuits.

Check out the video of this project below.

Via the contact form.

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Christmas lights with a MCU in each bulb

 

Having been disappointed by the generic offering of Christmas lights with small customization options, he decided to make fully customizable light decoration.

Small PIC12F609 MCUs along with RGB LEDs are placed on a board and daisy chained over a 3 wire cable. A master MCU is placed on one end of the cable and controls the color of the lights individually by sending addressed data over the wires.

Via the contact form.