Схемы - Безопасность - 10

Here's a simple lie detector that can be built in a few minutes, but can be incredibly useful when you want to know if someone is really telling you the truth. It is not as sophisticated as the ones the professionals use, but it works. It works by ...

Recent events point to the need for a simple device for testing cocktails and beers for excessive quantities of polonium. The Polonium Pen is a pocket-sized ion chamber with LED readout that is perfect for the job. Simply hold the Polonium Pen over ...

I’ve been reading a lot on how DTMF (Dual Tone Multi Frequency) tones work over the last couple of weeks. I’m sure you’ve noticed that when you press the keys on a standard telephone keypad, an audible ‘beep’ is ...

Andy Collinson This is a complete alarm system with 5 independent zones suitable for a small office or home environment. It uses just 3 CMOS IC's and features a timed entry / exit zone, 4 immediate zones and a panic button. There are indicators ...

Devices known as electrical key-lock can de found in many versions, but I will demonstrate you another interesting workaround of that device. Specificity of that device is a new way to read more keys using only one input of microcontroller. As you ...

Hundreds of yards away, in the dark of night, behind elaborate security and a pane of glass, a conversation ensues which will determine your future. (Just humor). Suppose you wanted to hear what was going on. What you need is a laser window-bounce ...

This is a simple circuit which can detect when you touch a sensor connected to one of the sensor inputs. It can be used to add a touch switch to your computer for example. It uses an AVR micro controller, the AT90S2313 . This is overkill. I can add ...