Kupfernerven

Here is a sample of a printed circuit board (parts placement layout) that I found inside the new book: Electronic Circuits Volume 1.1. This one is the 23rd circuit featured inside this book. The quality of the print, the design, and the layout is excellent. The use of professional CAD and graphic software is obvious. Nothing is hand drawn here. That is good. I like that. Following is an excerpt from the book about this particular circuit:

A highly reliable doorbell with "touch" switch can be easily constructed with few components. When the "touch" plate is touched by a finger, enough stray power line current is introduced into the transistor T1 so that it conducts. Succeeding transistors T2,T3,T4 also conduct and eventually trigger the doorbell (the bulb lights if one is installed).

The touch switch can be constructed from a copper plate, aluminum foil or similar metallic materials. The supply voltage can be between 6 and 12 volts. The standby current is around 6 mA. Obviously, the circuit can also be applied as an alarm device for metallic objects.

This is interesting for me. It is useful, simple to construct, and the printed circuit board layout is ready made. I just need to photocopy the layout and transfer it on my raw pcb. Super! The cover looks great too!

The publisher is Intellin Organization Technology Publishing Division (http://www.intellin.org) based in the USA.

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