Posts Tagged ‘metal detector’

Pipe Descaler

For many years now, magnetic (or electromagnetic) water descaler devices have been showing up on the shelves of Home Improvement and other DIY stores all over Europe. Despite the numerous studies completed on that subject, by manufacturers as well as by various consumer associations, none have been able to conclude on the efficiency of commercial pipe descalers in a decisive manner. Since electronic devices of this type are relatively expensive (especially when we discover what they are made of!), we decided to offer this project to our readers.

For the price of a few tens of pounds, you will be able to evaluate the state of your own faucets, pots, and other pipes. The device we’re offering as a project is identical to top-of-the-line items found on sale; in other words, it includes the bi-frequency option because it seemed that would be the best way to fight lime scale deposits. An initial astable oscillator, based on a traditional 555, labeled IC3, functions at around 10 kHz when the only capacitor C6 is operating; in other words, when T1 is blocked. The latter is controlled by another astable oscillator, based on IC1 this time, but which functions at about 1 Hz.
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Author: Christian Tavernier – Copyright: Elektor Electronics
Read more : http://www.extremecircuits.net/2010/06/pipe-descaler_8700.html

Metal detector by IC 4093

The circuit shown must represent the limits of simplicity for a metal detector. It uses a single 4093 quad Schmitt NAND IC and a search coil — and of course a switch and batteries. A lead from IC1d pin 11 needs to be attached to a MW radio aerial, or should be wrapped around the radio. If the radio has a BFO switch, switch this ON.
Since an inductor resists rapid changes in voltage (called reactance), any change in the logic level at IC1c pin 10 is delayed during transfer back to input pins 1 and 2. This is further delayed through propagation delays within the 4093 IC. This sets up a rapid oscillation (about 2 MHz), which is picked up by a MW radio. Any change to the inductance of L1 (through the presence of metal) brings about a change to the oscillator frequency. Although 2 MHz is out of range of the Medium Waves, a MW radio will clearly pick up harmonics of this frequency.

Source: Copyright Rev. Thomas Scarborough
The author may be contacted at scarboro@iafrica.com

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