Smooth brightness switch (ppya) is a device with Autonomous food intended for installation in a variety of crafts, for example, in the quality of the original light-color indicator included power.
In author's version ppya built into the stand for a toy Christmas tree. Food ppya is enabled when you install on a stand (rear trunk toy Christmas tree) "bag of gifts", which is a permanent magnet. The magnet closes the contacts of the reed switch, and ppya remains enabled as long as the bag is not moved to another place on the stand (side or front of the trunk of the tree).
Ppya (Fig.1) consists of:
- the resistive voltage divider R1-R2;
- sawtooth generator on the elements DA1.1, DA1.2, R4…R6, C1;
- analog inverter on the elements DA1.3, R7, R8;
- current amplifier FET VT1 and VT2;
- LEDs with ballast resistors HL1, R9 and HL2, R10.
With the closure of the reed switch SF1, the voltage of the battery GB1 enters divider voltage R1-R2, the midpoint of which is set half voltage power, ensuring the operating points of the operational amplifiers DA1.1, DA1.2, DA1.3. Capacitor C1 is periodically perezarias, provides a smooth increase and the decline of the output voltage (pin 1) DA1.1, which provides management VT2.
Output DA1.1 signal is also fed to the analog inverter (inverting amplifier with unity gain) DA1.3 and with its output (output 8) phase-shifted by 180°, the signal controls transistor VT1.
Transistors VT1 and VT2 are opened when you increase the voltage on their gates over +The 1.4 to+1.6 V and light up the LEDs. included in the stock circuit. Thus, the LEDs alternately (anti-phase) are switched with a frequency determined by chain R4-R5-C1. Potentiometer R5 generation frequency is set from 0.2 to 2 Hz. In the scheme ppya applied super-vivid LEDs yellow and green colors. The operating current of the LEDs HL1 and HL2 (not more than 20 mA) can be set by changing resistors R9 and R10 respectively. To improve the efficiency of current ppya LEDs {with regard to their high light output) can be selected from 0.1 to 5…10 mA. Ppya operable with the power from 4 to 6 In and consumes the current, determined mainly established by the currents of the LEDs.
In ppya used resistors OMLT, potentiometer R5 - JS4-1. The Capacitor C1 Is K50-35 or foreign production. In ppya used Quad opamps with low the current consumption and the allowable supply voltage 3 to 30 V, It can replace domestic CUT. but will have to be modified to route the Board (swap the terminals 4 and 11). HL1 led can be white color - ARL-3214UWC (20 CDs, 3 mm diameter), and HL2 - red - ARL-3214URC (diameter 3 mm).
The printed circuit Board ppya made of one-sided foil fiberglass with a thickness of 1.5 mm and a size 42x35 mm (Fig.2).
The diameter of the holes on the PCB the Board under the chip - 0,7…0,8 mm, other electronic components 0,8…1 mm. the printed circuit Board pattern can be transferred onto the foil by thermal transfer method or transferred using carbon paper and circled acid a permanent marker. Is suitable, for example, the markers Centropen 2846 SE PERMANENT" or similar, as well as markers for signing computer CD-ROM drive.
For etching the Board is used ferric chloride or a solution of salt and copper sulphate. Technology Board fabrication is described in detail in [1].
The battery GB1 is composed of 4 batteries A343 or A316 (if quiescent current less than 5 mA) and mounted in a support of insulating material together with the circuit Board and reed switch SF1. The LEDs are brought out through the upper wall of the housing and create a bright colored stains on the ceiling or white wall. The variant of the illumination of the branches of the Christmas tree.
Literature
Author: A. Oznobishin, Irkutsk