Flashlight Bug without rectifier. Encyclopedia of radio electronics and electrical engineering

Encyclopedia of radio electronics and electrical engineering / Lighting

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In a number of publications [1-3], it is proposed to use super-bright LEDs in electrodynamic flashlights ("bugs") instead of incandescent bulbs. To power such LED "light bulbs", it is recommended to insert a rectifier with an energy storage device (battery or ionistor) and a unit that regulates or stabilizes the rectified voltage into the "bug".

Simple experiments have shown that when switched on according to the scheme in Fig. 1, a, the LED shines without blinking and steadily from one half-wave of alternating voltage generated by generator G1.

To protect the LED from reverse voltage, you can not connect the VD1 diode if the amplitude of the alternating voltage does not exceed 10 V. According to [4-6], LEDs (withstand reverse voltage of 15.. even with intensive work, the lever could not "squeeze out" more than 20 V.

Therefore, all alterations are kept to a minimum. It is only necessary to make an LED "bulb" by mounting a super-bright LED into a standard base from an incandescent bulb. Necessary actions are described in detail in [3]. I recommend soldering the output of the LED to the threaded part of the base not from the inside, but from the outside, near a shallow cut made with a needle file in the base flange. The flux during tinning is a half (it is more convenient) of an aspirin tablet. The tinned base is washed with water, wiped and dried. After that, the LED leads are molded and soldered to the threaded and central parts of the base. It is advisable to fill the internal cavity of the base with an insulator. I used a drop of polyurethane foam. After its polymerization in a day, you can screw the "bulb" into the flashlight cartridge and use it as usual.

In order not to "disappear" the second half-wave of voltage, it is worth turning on another LED by soldering it in anti-parallel to the first one (Fig. 1, b). Enough space in the basement. This option is preferable to others due to the high light output and uniform loading of the generator. The circuit in Fig. 1c also loads the generator evenly, but since the LEDs are connected in pairs in series, at low generator speeds (during acceleration), the light lights up at a higher voltage. This scheme is more suitable for network operation.

If you use an ionistor as an energy storage device, then it is switched on according to the scheme in Fig. 2.

A few words should be said about the features of the work of ionistors in the "bug". When charging, it turned out that it was not possible to raise the voltage on the ionistor to the desired level, as they say, "on the forehead." After a charge of a certain value is "pumped" into the ionistor, the voltage does not rise higher, no matter how hard you try. But one has only to stop pumping and take a break of no more than 10 ... 15 s (in this case, the voltage on the ionistor drops by several tens of millivolts), as the next pumping passes easily until the next "obstacle", which again must be overcome with a short pause, etc. until the desired voltage level on the supercapacitor is reached. This phenomenon is especially noticeable with two ionistors. To raise the voltage to 4,41 V, it took more than twenty of these "steps *.

Do I need to raise the voltage on the ionistor to the nominal 5,5 V? I suppose not, because it is harmful to the ionistor. In [7], the following figures are given: at a temperature from -25°С to +75°С and an operating voltage of 0,6 Unom, the ionistor is capable of operating for 40000 hours (about 5 years). Hence the conclusion: with Unom = 5.5 V, the ionistor should not be charged to a voltage higher than 3.3 V. In addition, the average direct voltage drop across the LED is 3,6 V. This is higher than the "sparing" 3,3 V for the ionistor.

On a simple experiment, it was found that the discharge of an ionistor to one LED (voltage decrease from 4,41 V to 3,33 V) occurs in 1 min, and increased brightness is observed for the first 10 ... 20 s. After that, the ionistor is discharged with acceptable light output for another 20 minutes. Thus, there is no point in raising the voltage on the ionistor above 3,4 ... 3.5 V. The table shows the discharge time of the ionistor from 3,52 V and the brightness of the LED. The criterion was the legibility of the newspaper text when illuminated by a flashlight. These figures correlate well with the discharge voltages in a battery (two AA-size galvanic cells) electrician's flashlight, in which one LED is installed instead of an incandescent bulb.

(click to enlarge)

It will be easier to mount the circuit shown in Fig. 2 into the lantern body if you remove the traverse with the socket for the lamp base. In the vacated volume, ionistors C1, C2 (diameter - 18.5 mm, thickness - 5,5 mm), diode VD1 and LEDs HL1, HL2 are easily placed.

The SB1 button (MP11 microswitch) is located in place of the leash that moved the traverse relative to the focus of the headlight. A plate of foil-wrapped fiberglass was used as a common wire. The conclusions of all components, except for VD1 and SB1, are attached to it in the right places by soldering. The VD1 diode connects the "+" output of the ionistors to the button. The rest of the installation is made with a flexible insulated wire. The board is fastened with two screws with countersunk heads to the plastic cheek of the generator, which protects the rotor with magnets.

Literature

1. Improvement of the electromechanical lamp. -Radio, 2007. No. 9, p.58.
2. LED in an electromechanical lamp. - Radio, 2006, No. 8. P.57.
3. Tricky bug". - Radiomir, 2007. No. 9, P. 44.
4. Super bright LEDs. - Radiomir, 2004, No. 5 ... 7.
5. Super bright LEDs. - Radiomir, 2006. No. 11,12.
6. LED as a zener diode. - Radio, 1997, No. 3. P.51.
7. Ionistors of the K58 series. - Radio World, 2003, No. 6, P. 45.

Author: V. Miroshnichenko, Krasnodar

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