This is a simple circuit for DC Motor speed control (fan speed control, light dimming and etc) using the 555 timer. Also a good starting point for novices wanting to get their hands dirty with the 555 timer IC. Some would argue that this is not the most efficient approach.
Simple and dirty PWM For Motor Speed Control – [Link]
The brain of the Air-Byte transceiver is a tiny 8-pin PIC12F508 microcontroller. Operation is simple. The PIC simply monitors GPIO,0 connected to the PC serial port TX pin #3. When this pin transitions from logic low to logic high, the 12F508 generates the 40kHz IR carrier. During low periods the carrier is suppressed.
This provides a simple method for receiving serial data on one pin, and outputting serial data on another modulated at the IR detectors band-pass frequency. Very simple, yet very effective.
Transmit & Receive IR with Your PC Serial Port - [Link]
Macetech shares some fast action footage from his PCB fabbing process [via]
This is a video running at 4X speed, illustrating the etching process I’m using. The paint is removed from the copper-clad PCB in an Epilog laser cutter. After a wipedown with alcohol to remove any paint dust, the PCB is etched in ferric chloride solution.
Hot PCB lasering action - [Link]
I’m really really really excited to announce this new product. This one was directly conceived, funded, and produced by the RepRap Research Foundation (RRRF) as a direct result of the kind souls who have supported us so far. To get to the meat, the Sanguino is a new microcontroller board inspired by the Arduino. We took the biggest baddest 40-pin DIP that Atmel makes and made a board with it. Its based on the atmega644P which provides 64K of flash, 4K of ram, 32 GPIO pins, and tons of other stuff. The best part: its compatible with the Arduino software, which means all of your code should run on it no problem, and you can program it just as easily. You can buy a kit from the RRRF for $25 or check out the Sanguino website.
A simple two stage hybrid headphone amplifier project. The voltage stage uses a vacuum tube which feeds a MOSFET follower output stage. Unlike a lot of vacuum tube projects, this one is low voltage. Both the tube and mosfets use the same 12-13V power supply.
12AU7 / IRF612 MOSFET Hybrid Headphone Amplifier – [Link]
Another contest, another batch of cool projects! Once again, the Trossen Robotics Community (TRC) came through with some amazing ideas. We’re very excited to announce the winners of this round’s Trossen Robotics contest!
In case you’re new to the TRC, here’s a quick refresher on how this contest works: A wide range of talented and dedicated people come to our Project Showcase forum to show off a project they’ve been working on. After so many months, we (the Trossen Robotics team) evaluate each project, and score them in the following categories: “Wow” factor, Ingenuity, Creativity, and Presentation. We run this contest to help promote and encourage innovation and ingenuity. People are allowed to submit a wide range of projects ranging from robotics, automation, art, RFID, DIY, mods, inventions, and anything else demonstrating some form of technological creativity. We invite all bloggers to help promote the innovation that these unique individuals have demonstrated!
Enough talk, here are the winners from this round of the TRC Contest that we felt deserved recognition for their creations.
Trossen Robotics Community Contest - [Link]
The schematics for this DC/DC converter is built around the UC3843 generic, low cost PWM controller. This very common PWM controller generate a duty-cycle modulated square wave ranging from 0 to 100%, at a user fixed frequency of 100KHz.Here are some features: [via]
- Input voltage from 10V to 18V
- Output voltage from 20V to 28V adjustable
- Output current up to 5A for 3300mAh battery packs fast charge.
- Compact dimension (80×60mm)
- No heat sink or fan coolers even delivering up to 140W to the load.
High power 24V DC/DC converter - [Link]
The LiPo balancer cell acts like a big and very accurate zener diode; when the cell voltage is under a threshold fixed by the user the system is in “idle state” and watch only for the voltage with a equivalent resistance of some KOhm and a negligible current shunt. When the voltage reaches the threshold the balancer element will start to shunt current from the cell with an internal power resistor. [via]
LiPo Balancer – [Link]
This small realization, based on one of the most common IC (MAX232) is designed to create a small and convenient TTL to RS232 and vice versa convertor.All you need is 4 caps, one IC and 2 connectors. If you want to add a small regulator on the board (already foreseen on the PCB) you just need to add a 78L05 regulator and a cap. [via]
TTL to RS232 Converter – [Link]
Olivier de Broqueville writes:
The idea of this project came from my youngest son. He was dreaming of a small tool able to write symbols or pictures on a screen. As a graphic LCD (even bought at Crownhill ) was too expensive (or too easy??), the solution adopted was to pilot a matrix of Leds. This way, with only some cheap transistors, common red Leds, and a 16F628 , the dream could become reality. [via]
Fancy LEDs – [Link]