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 […]
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 […]
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. […]
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 […]
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 […]
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 […]
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 […]
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 […]
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 […]
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 […]
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 […]
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 […]
Spanner888 entered his Safer Alarm into the Open 7400 Logic Competition: This system provides a simple, effective and practical enhancement to existing alarm systems to tell you if your alarm has been triggered, tampered with, or lost power. Via the contact form.
HamRadio2008 made a demonstration video of the Bus Pirate in I2C mode. He hooked up the Bus Pirate to a test board he built with various I2C devices on it. He then used the I2C mode 7bit address scan to find all the addresses of the on board devices. Get your own handy Bus Pirate […]
Arthur entered his 74Clock into the Open 7400 Logic Competition. I uses a large 7 segment display and has a battery in case of power outage. A clock is a useful thing, so let’s build one. Via the contact form.
Daniel built a charge pump voltage inverter for the Open 7400 Logic competition. It uses the 74LV14 Schmitt trigger to provide a clocked signal, which is then connected to the inverted charge pump circuit to provide a -5V supply. Via the contact form.
Snorre built a Logic E-reader for the Open 7400 Logic Competition. It is a e-reader build completely from logic chips and 2 eproms. The e-books are displayed on a old analog oscilloscope. The front page says EEPROM instead of EPROM. I don’t have access to a burner right now, so i can’t fix it (ironically, […]
Viswesr wrote to us about the EFM32 MCU from Energy Micro: Recently, I discovered EFM32 MCU (ARM Cortex M3/0 based) from Energy Micro when looking for a very low power MCU. I was impressed on how this MCU reduces power consumption (refer: 10 factors that make the 10 factors that make the 32-bit EFM32 the […]
Jonathan entered his illogical Dickson doubler into the Open 7400 Logic Competition. My entry demonstrates how you can use the internal protection diodes and back powering to power a 74HC14 at a voltage “double” (minus diode drops) that of the primary power supply. This method was tested on a 74HC14 and a 74HC595, but it […]
HamRadio2008 demonstrates the Bus Pirate in UART mode. He is using a PIC18F45K20 MCU to read temperature data from a I2C sensor and then sends it over the UART to the computer serial port, via the MAX232 RS232 level converter. The Bus Pirate is used to monitor the UART signal coming from the board to […]