LED signal strength indicators have been around for decades. In the sound reproducing equipment of the middle class, they almost completely replaced other level control devices: pointer, LCD matrices. The reason is the simplicity and cheapness of the design, good optical performance. However, there are options for LED indicators of a very complex and advanced design, including those with microprocessor control. But in this article, we will not delve into complex schemes. Let’s make an indicator with our own hands, which, probably, is not simpler.
It will take
To be completely honest, this design cannot be fully called a level indicator. There can be no talk of any exact measurements in this homemade product. Rather, we can say that this is just a decoration of the equipment – the LEDs will flash to the beat of the music. Like on early cheap Chinese radios, if anyone else remembers them. Our indicator will be assembled without the use of transistors and microcircuits, without the manufacture of a printed circuit board – by surface mounting. Begin.
Making a simple level indicator
Our indicator will be “pseudo-two-channel”. This means that we select the number and colors of LEDs, respectively – in pairs. Two pairs of reds, two pairs of yellows and the same number of greens.
Having arranged the LEDs in an appropriate way, we connect their negative terminals to each other by soldering.
We solder 470 ohm current-limiting resistors to the pluses.
Next, diodes are soldered to the terminals of the resistors. Pay attention to the correct wiring of their poles. Diodes we took 1N4007. But instead of them, you can use any silicon with a permissible forward current of 0.3 A. The voltage drop across each of them will be about 0.7 V. This is what will create the effect of sequential ignition of a line of LEDs, depending on the signal level.
Complete the assembly of a pair of electrolytic capacitors 470uF 25V, soldered in series and a pair of diodes. They form a voltage doubler. It is needed to rectify and double the input voltage. That’s all, the scheme is ready.
Voltage is supplied to the indicator directly from the speaker of the sound reproducing device.
Turn on. Everything is working!
It should be noted that the volume of sound playback directly affects the number and brightness of the LEDs that light up. The louder, the brighter the LEDs light up.
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