I show you how to make without IC 20 levels dot display mode LED VU Meter using BC547 or TUN (Transistor Universal NPN).
use BC547 Transistors. You can use any other TUN (Transistor Universal NPN), but you have pay attention into the Transistor pins (Emitter Base Collector).
- For the genuine BC547 Transistor pins structure: pin 1 is Collector, pin 2 is Base, pin 3 is Emitter, (CBE).
- For the genuine C1815 or C945 Transistor pins structure: pin 1 is Emitter, pin 2 is Collector, pin 3 is Base, (ECB).
- For the genuine FCS9013 (C9013) or FCS9014 (C9014) Transistor pins structure: pin 1 is Emitter, pin 2 is Base, pin 3 is Collector, (EBC).
Why should use transistors version
You may have a question. Is it better than IC? I cannot tell you. It is the best VU meter. But I can show you the transistor is so great all the time.
Easy to get them—Although they are quite ancient. But it is still always popular.
For example:
2SC458 transistor, now The factory quit producing it. But we can use other transistors instead like 2SC828, 2SC945, 2SC1815, etc.
Cheap—They are inexpensive when compare with IC. Although we need to use a lot of transistors. If it breaks out. You can fix it one by one, do not change it all.
It is different from the IC. You need to change IC only.
Simple circuit—suitable for learning basic electronics
Next, four diodes D1, D2, D3, and D4 pass the input audio signal. They have 2 functions.
First, rectify the audio signal, AC voltage to DC voltage.
Second, divide the audio signal to gradually decrease, respectively.
To forward to each the transistors Q1-Q4 through Resistors, R5-R8. They limited bias current to the base of Q1-Q4 to increase current up to each collector.
To drive LED1-LED4, to show the level of the signal. The LED1 displays an audio level with the least light. And the LED4 shows the most level signals.
I think you may not understand I said. Back…reading.
Each diode has a voltage across is 0.6V. Suppose the signal is 1.8V.
It causes the current can flow to three diodes, D1, D2, D3, So, LED1-LED3 glow up. But LED4 and LED5 will go out.
Note: likewise you can see the second circuit that using more LEDs, too.
25 LEDs VU meter Circuit (Increase LED)
The weakness of the previous circuit is cannot display low voltage. So, we need to improve it.
In the circuit below. It has a voltage doubler circuit, C1, C2, R1, R2.
They approximately double an incoming AC voltage. Also, the output is DC voltage.
Adding LEDs for 25 LEDs Analog VU Meter circuit using transistors
Make the audio signal into more voltage. So, all transistors can drive all LEDs to emit light much more.
How it works
First of all, when applying the power supply to the circuit. And VR1 passed the input signal and adjust the sound more or less.
Then, flows through the C1 signal coupling.
Next, the signal goes into the circuit to increase the voltage with D1 and D2. Which both diodes rectifier AC to DC with positive and negative together.
After that, DC voltage comes to C2 to filters into a smooth DC voltage.
The first part of the signal will flow through R1 to the base of Q1. It works to drive LED1-LED5 to light up.
The remaining signal is sent through diodes D3, D4 and D5. This will serve to break the sound signal to gradually decrease, respectively.
To forward to the transistors Q2-Q4, each level of the signal strength coming.
Then expand to the LED current to light the rhythm music.
I show you how to make without IC 20 levels dot display mode LED VU Meter using BC547 or TUN (Transistor Universal NPN).
use BC547 Transistors. You can use any other TUN (Transistor Universal NPN), but you have pay attention into the Transistor pins (Emitter Base Collector).
- For the genuine BC547 Transistor pins structure: pin 1 is Collector, pin 2 is Base, pin 3 is Emitter, (CBE).
- For the genuine C1815 or C945 Transistor pins structure: pin 1 is Emitter, pin 2 is Collector, pin 3 is Base, (ECB).
- For the genuine FCS9013 (C9013) or FCS9014 (C9014) Transistor pins structure: pin 1 is Emitter, pin 2 is Base, pin 3 is Collector, (EBC).
Why should use transistors version
You may have a question. Is it better than IC? I cannot tell you. It is the best VU meter. But I can show you the transistor is so great all the time.
Easy to get them—Although they are quite ancient. But it is still always popular.
For example:
2SC458 transistor, now The factory quit producing it. But we can use other transistors instead like 2SC828, 2SC945, 2SC1815, etc.
Cheap—They are inexpensive when compare with IC. Although we need to use a lot of transistors. If it breaks out. You can fix it one by one, do not change it all.
It is different from the IC. You need to change IC only.
Simple circuit—suitable for learning basic electronics
Next, four diodes D1, D2, D3, and D4 pass the input audio signal. They have 2 functions.
First, rectify the audio signal, AC voltage to DC voltage.
Second, divide the audio signal to gradually decrease, respectively.
To forward to each the transistors Q1-Q4 through Resistors, R5-R8. They limited bias current to the base of Q1-Q4 to increase current up to each collector.
To drive LED1-LED4, to show the level of the signal. The LED1 displays an audio level with the least light. And the LED4 shows the most level signals.
I think you may not understand I said. Back…reading.
Each diode has a voltage across is 0.6V. Suppose the signal is 1.8V.
It causes the current can flow to three diodes, D1, D2, D3, So, LED1-LED3 glow up. But LED4 and LED5 will go out.
Note: likewise you can see the second circuit that using more LEDs, too.
25 LEDs VU meter Circuit (Increase LED)
The weakness of the previous circuit is cannot display low voltage. So, we need to improve it.
In the circuit below. It has a voltage doubler circuit, C1, C2, R1, R2.
They approximately double an incoming AC voltage. Also, the output is DC voltage.
Adding LEDs for 25 LEDs Analog VU Meter circuit using transistors
Make the audio signal into more voltage. So, all transistors can drive all LEDs to emit light much more.
How it works
First of all, when applying the power supply to the circuit. And VR1 passed the input signal and adjust the sound more or less.
Then, flows through the C1 signal coupling.
Next, the signal goes into the circuit to increase the voltage with D1 and D2. Which both diodes rectifier AC to DC with positive and negative together.
After that, DC voltage comes to C2 to filters into a smooth DC voltage.
The first part of the signal will flow through R1 to the base of Q1. It works to drive LED1-LED5 to light up.
The remaining signal is sent through diodes D3, D4 and D5. This will serve to break the sound signal to gradually decrease, respectively.
To forward to the transistors Q2-Q4, each level of the signal strength coming.
Then expand to the LED current to light the rhythm music.
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