When you need precise heating — like for the acetone polishing shown above — the control hardware is everything. Buying a commercial, programmable, controller unit can cost a pretty penny. Instead of purchasing one, try creating one from scratch like [BrittLiv] did.
[BrittLiv] is a Chemical and Biological Engineer who wanted something that performs well enough to be relied upon as a lab tool. Her design utilizes a plain, old hot plate and with some temperature feedback to run custom temperature ramps from programs stored on an SD card.
The system she developed was dealing directly with temperatures up to 338°F. The heating element is driven from mains, using an SSR for control but there is also a mechanical switch in there if you need to manually kill the element for some reason. An ATmega328 monitors the heating process via an MAX6675 thermocouple interface board. This control circuitry is powered from a transformer and bridge rectifier inside the case (but populated on a different circuit board).
She didn’t stop after getting the circuit working. The project includes a nice case and user interface that will have visitors to your lab oohing and aahing.
Filed under: hardware
, tool hacks
The PCWorld website posted an article about the open hardware Olimex OLinuXino single board computer. The article compares it to the Raspberry Pi, noting that the while Raspberry Pi hypes their board as open hardware, they have not released their CAD files or complete schematics yet and utilize components that are not available in small quantities. Olimex designed the OLinuXino board to address some of these concerns. All CAD files and complete schematics are available and they use an easy to find CPU. They use the Creative Commons Share-Alike license for all hardware and the GNU GPL license for all software associated with the OLinXino. The board uses a faster CPU than the Raspberry Pi and runs Android, debian, and other GNU/Linux distros. They also tout the board as being noise immune and working in industrial environments with a temperature range of -25 C to 85 C. The OLinuXino uses the standard nano-ITX form factor. The board is priced at 45 Euros (about $57). One point where we’d have to say the Raspberry Pi wins is on the name. It’s unclear how to pronounce OLinuXino, which can’t be good from a marketing standpoint.
So what about the actual specifications?
- A13 Cortex A8 processor at 1GHz, 3D Mali400 GPU
- 512 MB RAM
- 6-16VDC input power supply, noise immune design
- 3 + 1 USB hosts, 3 available for users, 1 leads to onboard pinout
- 1 USB OTG which can power the board
- SD-card connector for booting the Linux image
- VGA video output
- LCD signals available on connector so you still can use LCD if you diasble VGA/HDMI
- Audio output
- Microphone input
- RTC PCF8536 on board for real time clock and alarms
- 5 Keys on board for android navigation
- UEXT connector for connecting addtional UEXT modules like Zigbee, Bluetooth, Relays, etc
- GPIO connector with 68/74 pins and these signals:
- 17 for adding NAND flash;
- 22 for connecting LCDs;
- 20+4 including 8 GPIOs which can be input, output, interrupt sources;
- 3x I2C;
- 2x UARTs;
- SDIO2 for connectinf SDcards and modules;
- 5 system pins: +5V, +3.3V, GND, RESET, NMI
- Optional low-cost 7″ LCD with touchscreen