The heat of summer. The sky is cloudless. Without irrigation the garden can not be saved. In this case, it is good to use a plant that waters itself. The device is an electronic relay on the transistor VT1, the base and the emitter of which is connected to the plates of conductive material stuck in the ground at a distance of 3 — 3.5 cm from each other. Because raw land has a low resistance, it can be considered that the base of the transistor is directly connected to its emitter (the transistor is closed). But as soon as the soil begins to dry, a semiconductor device is opened, and actuates electromagnetic relay K1 and its contact pair completing a circuit of the actuator of the electromagnet, lifting the flap of the water tank irrigation.
The proposed electrosurgery, I am sure, will find its rightful place in the kitchens have gas stoves, when the ignition of the gas burner appliances and other devices with the “blue fuel”. It is convenient and trouble free. It can make for a night or two, pre-armed with a small piece of one-sided foil fiberglass and a minimum of inexpensive and common parts. A faithful guide to action will serve as a sketch of the printed circuit Board and Assembly drawing.
I made welding machine is a well-proven in practice a modernized version of the device description and drawings of which are published in the journal “modelist-Konstruktor” No. 3, 1966. Most importantly — new “svarochnik” significantly more powerful than its predecessor, easier to manufacture and operate. In the absence of the kind of “bells and whistles” it allows you to securely connect steel sheet with thickness up to 3 mm. However, the mode of operation is one of the most necessary most homebrew spot welding.
Familiar to many hams, the situation: once the scheme is built, configured, but… to Squeeze it into some kind of “soap” not want to, but new to “diamond” the right frame there is neither time, nor forces. Had to find a way out of similar situations and me while in one of the publications, “Model construction” did not find a clue. It turns out that enterprising and slopestyle Siberians, which wrote the log, began the production of fine gift boxes of foil materials commonly used in the manufacture of printed circuit boards. Moreover, the simplest technology: the workpiece-scan in the field of future folds (from the base-insulator), they made cuts, and after giving it a box shape was probabaly foil joints.
