Our friend Gio from DIY Audio Projects has sent in a cool Push-Pull Tube Amp Build. This tube amp fits into a 8 X 12 inch chassis and looks fantastic! Now if only we could find a drugstore with a tube tester. With cool equipment like this and tube TV troubleshooting guides popping up there is sure to be demand for tube testers once again?

"The basic design has been around for a long time (50 years or so). The problem with early applications was that it was difficult to force it to operate in a linear manner. It can only function in a class-A mode with both tubes always conducting. The reason this circuit is attractive is that it eliminates the need for a phase splitter stage. It requires only a single-ended driver. The advent of solid state electronics provided a solution to the problem. A simple application of a common LM317 IC voltage regulator converts it to a very accurate constant current source (CCS). Using a CCS in the cathode circuit of the SIPP stage forces it to operate in class-A. What was a sort of a mediocre output stage thus becomes highly accurate and quite excellent."

Surface mount rework stations are very expensive, Openschemes shows us that it is possible to perform Surface Mount Component Removal using a Heat Gun.

"Now it doesn’t matter much WHICH heat gun you use, although it should be able to produce a good bit of air at >300C. In our experience, long heating times due to using a weaker gun are the biggest cause of PCB burn, bulge, or trace peel.
A drawback of high air setting is the risk of blowing neighboring devices (usually tiny SMT resistors or capacitors) off their pads and maybe even off the board! You will need to weigh the risk at rework time and choose your airflow accordingly – if you have a device that’s simply SURROUNDED by tiny SMT caps, you may want to use lower air or make a foil cone for your heatgun to contain the hot air to the desired area. Here’s the heat gun we used here, peak temp is about 550C."

A Nerdkit microcontroller is used in this Capacitive Touch Sensor Halloween Pumpkin for some great effects! Full details are provided so that you can add this cool effect to your own projects. The sensor components are just aluminum foil which is great since you probably have some in your kitchen cupboard.

Thanks Humberto.

"Capacitive proximity sensors work because people are mostly water, and water is a very polar molecule, and is easily turned to align with any applied electric field. In fact, water has a "permittivity" (dielectric constant) that is about 80 times better than air! When a given voltage is applied between the two plates of any capacitor, an electric field is created between the plates. In the region where there’s a dielectric, the electric field is actually smaller than it is in air (for water, just 1/80th of the field strength), so your first instinct might be to think that the capacitance decreases as well. However, because the applied voltage must manifest as a product of electric field and distance, the electric field strength in the non-dielectric regions actually goes up substantially. Overall, the energy stored in the electric field per unit volume of space has to do with the square of electric field strength, so all in all, the stored energy and capacitance both increase when a dielectric is inserted."

This GPS Hunt Project is very interesting, the box is electronically locked and the only way to open it (without using the emergency backdoor) is to go to a certain location. It gives lets you know how far from the target location you are each time the button is pressed but you only have 50 presses to figure it out.

 Thanks for the tip Jim.

"Major components

You might remember Michael Saunby, he was the guy that had the interesting clock that we were trying to determine heritage for. The clock was almost featured on Antiques Roadshow but unfortunately was left on the cutting room floor. Michael works with lots of antique electronics and this 1930 vintage amplifier and speaker is a great example of what can be done with a mix of old and new.

"The original amplifier was typical for a 1930s broadcast receiver, a single ended pentode with tone correction. The valve chosen was a high slope pentode type AC/SP3; as used by the BBC in pre-amplifiers from late 1930s through to the 1950s."

Need to get into a tricky lock, why not make a lock pick out of one of your old hard drives? That is what the guys over at sorgonet.com did.

Not your typical player piano where the piano automatically plays a nice tune. This creation plays many notes simultaneously to simulate spoken words. What would be impressive is if a person could achieve the same effect using only his fingers.

Via: Anything and Everything