[Rui] enjoys his remote-controlled helicopter hobby and he was looking for a way to better track the temperature of the helicopter’s engine. According to [Rui], engine temperature can affect the performance of the craft, as well as the longevity and durability of the engine. He ended up building his own temperature logger from scratch.
The data logger runs from a PIC 16F88 microcontroller mounted to a circuit board. The PIC reads temperature data from a LM35 temperature sensor. This device can detect temperatures up to 140 degrees Celsius. The temperature sensor is mounted to the engine using Arctic Alumina Silver paste. The paste acts as a glue, holding the sensor in place. The circuit also contains a Microchip 24LC512 EEPROM separated into four blocks. This allows [Rui] to easily make four separate data recordings. His data logger can record up to 15 minutes of data per memory block at two samples per second.
Three buttons on the circuit allow for control over the memory. One button selects which of the four memory banks are being accessed. A second button changes modes between reading, writing, and erasing. The third button actually starts or stops the reading or writing action. The board contains an RS232 port to read the data onto a computer. The circuit is powered via two AA batteries. Combined, these batteries don’t put out the full 5V required for the circuit. [Rui] included a DC-DC converter in order to boost the voltage up high enough.
Every now and then a remote control acts up. Maybe you are trying to change the channel on your television and it’s just not working. A quick way to determine if the remote control is still working is by using a cell phone camera to try to see if the IR LED is still lighting up. That can work sometimes but not always. [Rui] had this problem and he decided to build his own circuit to make it easier to tell if a remote control was having problems.
The circuit uses a Vishay V34836 infrared receiver to pick up the invisible signals that are sent from a remote control. A Microchip 12F683 processes the data and has two main output modes. If the remote control is receiving data continuously, then a green LED lights up to indicate that the remote is functioning properly. If some data is received but not in a continuous stream, then a yellow LED lights up instead. This indicates that the batteries on the remote need to be replaced.
The circuit also includes a red LED as a power indicator as well as RS232 output of the actual received data. The PCB was cut using a milling machine. It’s glued to the top of a dual AAA battery holder, which provides plenty of current to run the circuit.
It’s always nice to see hackers pick up stuff headed for the landfill and put it back in action with a quick repair and upgrade. [Septillion] found a wireless remote controlled AC outlet in the junk bin and decided to do just that. A nice spin-off of such hacks is that we end up learning a lot about how things work.
His initial tests showed that the AC outlet and its remote could be revived, so he set about exploring its guts. These remote AC outlets consist of an encoder chip on the remote and a corresponding decoder chip on the outlet, working at 433MHz. Since the various brands in use have a slightly different logic, it needed some rework to make them compatible. The transmit remote was a quick fix – changing the DIP switch selected address bits from being pulled low to high and swapping the On and Off buttons to make it compatible with the other outlets.
Working on the AC outlet requires far more care and safety. The 230V AC is dropped down using a series capacitor, so the circuit is “hot” to touch. Working on it when it is powered up requires extreme caution. A quick fix would have been to make the changes to the address bits and the On/Off buttons to reflect the changes already made in the remote transmitter. Instead, he breadboarded a small circuit around the PIC12F629 microcontroller to take care of the data and address control. Besides, he wanted to be able to manually switch the AC outlet. The relay control from the decoder was routed via the microcontroller. This allowed either the decoder or the local manual switch from controlling the relay. Adding the PIC also allowed him to program in a few additional modes of operation, including one which doubled the number of outlets he could switch with one remote.
Here’s a design challenge for you: make a temperature sensor for any computer. If you’re an exceptionally clever smart ass, you’ll probably write some code to report the CPU temps. Others who take the exercise seriously will probably build something with a 1-wire temp sensor, a microcontroller, and all the hardware required to do that.
[Michael] had a better idea. He did it with just two components. One of those components is a USB connector.
The only reason is project could be created is a rather new part from Microchip, the PIC16F1455. This microcontroller doesn’t require a crystal, can do USB without any additional parts, and has an integrated temperature sensor. [Michael] whipped up a project to set up a USB CDC serial device, read the temperature with the ADC (thanks to a very helpful app note), and sends the temperature to a computer once a second.
Despite being built out of only two components, this could actually be a useful device. The PIC is a USB serial device, and this can be used with any computer made in the past 15 or so years. It would hardly take any code at all to read the temperature with another program, and it’s a very inexpensive build. We have to give style points for soldering a microcontroller directly to a USB connector, too.
Sometimes finding a short-circuit is easy, especially after the magic smoke has escaped. Finding a short on a newly etched or milled board though, can be a maddening task. Many of us have been there – wrestling with multimeter probes under a magnifier trying to find the offending bit of copper that is the source of all our problems. [Jaromir] designed Shorty to make this task a little bit easier.
Shorty is a short-circuit finder – but it’s not exactly like the one you would find on a typical multimeter. [Jaromir] used MCP6041 Op-Amp to detect resistances down to the order of tens of milliohms. Determining an exact resistance measurement at these levels would require a heck of a lot of calibration. When looking for a short though, [Jaromir] is only concerned with the relative value – is he getting closer to or further away from the short. He determines this by sound. The Op-Amp output is sent to the Pro Trinket’s ADC input. The trinket drives a speaker with lower or higher tones based upon the ADC voltage. Much like the childhood game of “hot and cold”, Shorty will direct you right to your short!
There’s still time to enter the Trinket Everyday Carry Contest. The main contest runs until January 2, but we’re having random drawings every week! Don’t forget to write a project log before the next drawing at 9pm EST on Tuesday, December 30th. You and all of the other entrants have a chance to win a Teensy 3.1 from The Hackaday Store!
When buying anything, you’re going to have a choice: good, fast, or cheap. Pick any two. A plumber will fix a drain good and fast, but it won’t be cheap. The skeezy guy you can call will fix a drain fast and cheap, but it won’t be good.
Such it is with radios. You can have long-range (good), high bandwidth (fast), or a low price (cheap). Pick any two. The Internet of Things demands a cheap, long-range radio module, but until now this really hasn’t existed. At Electronica last week, Microchip demoed their IoT solution, the LoRa. This module has a 15km (rural) or ~3km (heavy urban) range, works for a year on two AAA batteries, and is very cheap. Bandwidth? That’s crap, but you’re not streaming videos to your shoe.
Continue reading “The Future of the Internet of Things”
[Herp] just shared a nice 1MHz Arbitrary Waveform Generator (right click -> translate to English as google translation links don’t work) with a well designed user interface. His platform is based around a PIC32, a TFT module with its touchscreen and the 75MHz AD9834 Direct Digital Synthesizer (DDS). Of course the latter could generate signals with frequencies up to 37.5MHz… but that’s only if two output points are good enough for you.
As you can see in the video embedded below, the ‘tiny dds’ can generate many different kinds of periodic signals and even ones that are directly drawn on the touchscreen. The offset and signal amplitude can be adjusted using several operational amplifiers after the DDS ouput and a separate SMA TTL output is available to use a PIC32 PWM signal. The platform can read WAV audio files stored on microSD cards and also has an analog input for signal monitoring. Follow us after the break for the video.
Continue reading “An Open Source 1MHz Arbitrary Waveform Generator with an Awesome UI”