LED double flashes.

LED double flashes.

The proposed indicator is a compact economical attachment to any wireless devices that require eye-catching alarm. The indicator is different from the original combination of traditional outbreaks and pauses between them. His work can be roughly described as: flash, flash — pause, etc. Therefore confuse this indicator with the other can not.

The indicator consists of:

— clock on flashing LED HL1 with limiting resistor R1, generating rectangular pulses with a repetition period of about 0.5 seconds;

— binary counter divider DD1.1;

— logic element 2I on discrete elements VD1, VD2, R2;

— Key current FET VT1 and its drain load — red LED HL1 with current limiting resistor R3;

— filter capacitor C1.

At power toggle switch SA1 voltage from the battery to the anode GB1postupaet flashing LED HL1, and the clock starts. With cathode HL1 rectangular pulses with a repetition period of about 0.5 to the input V (terminal 2) DD1.1. Each falling edge of the input voltage V DD1.1 increases the counter by one. Cycles accounts DD 1.1 (0000 to 1111) are repeated periodically. The outputs of 1, 2, 4, 8 DD1.1 signals have a duty cycle 2. On 1 DD1.1 output pulse frequency is half the frequency of the clock HL1-R1 and about 1 Hz.

At the output 4 DD1.1 pulse frequency four times less than the output 1, so the log. «1» at the output of NAND gate 2I (anodes VD1 and VD2) occurs when its both inputs «1». This condition corresponds to the binary code is 0101 (decimal 5), 0111 (decimal 7), 1101 (decimal 13), 1111 (decimal 15).

When «1» from the output element 2I supplied to the gate of the FET VT1, it opens the channel resistance (source-drain) is sharply reduced, and the load HL2-R3 is applied practically full battery voltage GB1. Red LED HL2 to within 0.5 with bright lights.

When «0» on the output element 2I VT1 is closed and de-energized LED HL2. The duration of pauses between the output of small codes DD1.1 0101-0111 and 1101-1111, ie the luminance of HL2, with 0.5, the duration longer pauses between 0111-1101 and 1111-0101 Codes

— 2.5 s. In other words, the light evenly from the following half-second flashes HL2 reserves the 1st and 2nd, and 3rd and 4th «cuts»; leaves 5 and 6, and 7 and 8 «cuts»; 9i10 reserves, and 11 th and 12 th «Cut», etc. Further, these cycles are repeated periodically.

The device used fixed resistors MLT, S2-23, S2-33. Capacitor C1

— Ceramic, KM, K10-7, K10-17. Diodes VD1 and VD2 — KD503, KD510, KD520 KD522 … any letter index. HL1 LED can be replaced by ARL-5013URC-B, a HL2

— Super-bright green ARL- 5213PGC (05 mm, 20 mA, 12 kd) or OSBG5111A (05 mm, 20 mA, 18 kd) .KP505 (including pinout), BS170 and even powerful type IRF540. IC DD1 — K561IE10 has foreign analogue MS14520. Toggle SA1- type MT1, MTS-102, SMTS-102 or any other. When soldering such as tumblers MTS (SMTS) should apply heat to avoid overheating of their contacts. It is recommended to first clean contact toggle switch, moisten with liquid rosin and tinned with. Solder contacts operate after they have cooled down (after a few minutes of tinkering).

The printed circuit board is made of WIS-sided fiberglass foil 1.5 mm thick and the size of 33×28 mm. Figure print can be transferred to copper foil by thermal transfer or use of carbon paper and a permanent marker circled with acid (for example, «Centropen 2846») or a marker to sign the CD-ROM drive.

Before installing the electronic components to the printed circuit board to be solder jumper from solid wire to a heat-resistant insulation. The soldering of electronic components should maintain a low voltage soldering iron or a soldering iron with grounded tip.

Brightness HL2 depends on the resistance of the resistor R3. Rated operating current of the LED HL2 — 20 mA. When the voltage on the HL2 1,7 V and 4.8 V supply voltage resistance R3 can be reduced to 150 ohms. However, super-bright LEDs provide illumination bright enough even at low current (0.1 … 1 mA), so to save energy GB1 resistance R3 can be increased significantly.

To install the required operating current HL2 resistor R3 is temporarily replaced by a chain of constant resistor 100 .. .120 ohms and trimming

4.7 .. .27 ohms connected in series. Shutter VT1 temporarily disconnected from the anodes’ VD1, VD2, and plug into the ‘+’ power. Milliammeter include broken wire from HL2, trimmer set the required operating current HL2, turn off the power desoldering chain is measured by its total resistance of a fixed resistor and pick up the nearest rating.

Resistor R1 sets the operation mode flashing LED HL1, and the resistance may be from 1 to 120 ohms. However, the change in resistance R1 changes HL1 brightness over a wide range and only slightly (to 10%) of its blink rate. A variety of resistor R1 in the range 1 … 10 k leads to an unjustified increase in current consumption.

The indicator remains operational with voltage GB1 from 3.2 to 6 V. When used as a flashing LED HL1 ARL3014URD-B maximum voltage indicator can reach 10 W.

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