engineerguyvideo writes: [via]
Bill details how a microwave oven heats food. He describes how the microwave vacuum tube, called a magnetron, generates radio frequencies that cause the water in food to rotate back and forth. He shows the standing wave inside the oven, and notes how you can measure the wavelength with melted cheese. He concludes by describing how a magnetron generates radio waves.
How a Microwave Oven Works - [Link]
Sorry for the lack of photos in this article, but we didn’t think about it being worth reporting until after it had all happened. Infact, we were concerned about retaining any evidence of the events. Inspired by the many toaster-oven reflow projects floating around the Internet, we set out to acquire the power to solder all those tiny SMD components ourselves. Toaster ovens aren’t that common in the UK and we were aiming for the lowest cost possible, so we hit ebay in search of a bargain. A very cheap Black and Decker Toast-R-Oven was on offer. The description was “only used a few times”, and the grainy photos showed an indeterminate “foreign” plug with an adaptor. Now, we aren’t generally in the habit of assuming that “some bloke on ebay” must know what he’s doing with electricals, but with the auction starting at £5 (and not going up a huge amount from there by the end) it seemed like a good idea.
Engineering of a reflow oven controller - [Link]
One of SMD soldering techniques is using a reflow soldering oven. Reflow soldering technique is used when it is impossible to solder components by hand. These may include ball grid arrays (BGA), small pitch quad flat packs. Or simply solder any SMD element to make board look professional and smooth.
Special care has to be taken when soldering with oven. Specialized ovens have controllers built in that control overall soldering process by adjusting temperatures, but if you are using regular oven that is much cheaper than specialized soldering ovens, you need to build a controller. Controller has to adjust soldering oven temperature according to chart that is stored in memory. Together with keypad this gives great interactivity.
Soldering oven controller is based on ATmega32 microcontroller that uses ADC input to read NTC temperature sensor. Current temperature is displayed on graphical LCD as chart. As authors state – system works OK, maybe additional blower could be added for cooling speed controlling as without fan it is to slow. [via]
Reflow Soldering Oven controller with graphical LCD Display - [Link]