Stereo Amplifier 12V 20W Full Power Performance Scheme

Posted by Erick Widyanto

For those of you who like to audia definitely want to listen to the music in good quality. a power which is not much but can produce incredible sound. And we will learn how to create a series of amplifiers that we dream.
This is an ideal project for anyone wanting a compact stereo amplifier that can run from a 12V battery. It could be just the ticket for buskers who want a small but gutsy amplifier which will run from an SLA battery or it could used anywhere that 12V DC is available – in cars, recreational vehicles, remote houses with 12V DC power or where ever.
12 Volt 20W Stereo Amplifier circuit schematic 
Because it runs from DC, it will be an ideal beginner’s or schoolie’s project, with no 240VAC power supply to worry about. You can run it from a 12V battery or a DC plugpack. But while it may be compact and simple to build, there is no need to apologise for “just average” performance. In listening tests from a range of compact discs, we were very impressed with the sound quality.

Long-time readers might recall that we presented a similar 12V power amplifier design back in May 2001. It was a similar configuration to this one but it is now completely over-shadowed by the much lower distortion and greatly improved signal-to-noise ratio of this new design. In fact, let’s be honest: the previous unit is not a patch on this new design. It used two TDA1519A ICs which resulted in distortion figures above 1% virtually across the board and a signal-to-noise ratio of only -69dB unweighted.

However, by using the TDA­7377 power amplifier IC and making some other improvements, the THD (total harmonic distortion) of the new design is about 50 times better than the older unit (see performance graphs for details). The bottom line is that the THD under typical conditions is around just 0.03% or less. It is also able to deliver more output power due to the improved output transistors in the new power amplifier IC.

In addition, its idle power consumption is low – not much more than 1W. As a result, if you don’t push it too hard it will run cool and won’t drain the battery too quickly. And because the IC has self-protection circuitry, it’s just about indestructible. It will self-limit or shut down if it overheats and the outputs are deactivated if they are shorted.

12V 20W Stereo Amplifier circuit schematic 
With a 12V supply, the largest voltage swing a conventional solid-state power amplifier can generate is ±6V. This results in a meagre 4.5W RMS into 4O and 2.25W RMS into 8O, without considering losses in the output transistors. Even if the DC supply is around 14.4V (the maximum that can normally be expected from a 12V car battery), that only brings the power figures up to 6.48W and 3.24W for 4O and 8O loads respectively – still not really enough.

There are three common solutions to this problem. The first is to boost the supply voltage using a switchmode DC converter. This greatly increases the cost and complexity of the amplifier but it is one way of getting a lot of power from a 12V supply. However, we wanted to keep this project simple and that rules out this technique.

There are variations on the boosting method, such as the class H architecture used in the TDA1562Q IC featured in the Portapal PA Amplifier (SILICON CHIP, February 2003). It is able to achieve 40W/channel but with >0.1% THD. In that case, the amplifier output itself provides the switching for a charge pump. The second method is to lower the speaker impedance. Some car speakers have an impedance as low as 2O, which allows twice as much power to be delivered at the same supply voltage. However, we don’t want to restrict this amplifier to 2O loudspeakers.

More aboutStereo Amplifier 12V 20W Full Power Performance Scheme

Schematics-Charging Battery Indicator

Posted by Erick Widyanto

We will learn how to make Schematics-Charging Battery Indicator. is very easy, you can make it with the instructions that I will give below. Think not too clear on how to make this circuit is very simple and will not trouble you.
Schematics-Charging Battery Indicator

Battery-Charging Indicator Circuit Diagram
You should have some idea of the charging current. In case you use an adaptor which is adjustable but of the unregulated, low output current type, you can adjust the current by adjusting the output voltage.
You have to know if the current actually flows through the battery. A current-detecting indicator is therefore much to be preferred over a voltage indicator.
To prevent you from forgetting all about the charging cycle, the indicator should be visible from wherever you pass by frequently. Using the circuit shown here, the LED lights when the baseemitter potential of the transistor exceeds about 0.2 V. Using a resistor of 1 ? as suggested this happens at a current of about 200 mA, or about 40 mA if R1 is changed to 4.7?. The voltage drop caused by this indicator can never exceed the base-emitter voltage (UBE) of the transistor, or about 0.7V. Even if the current through R1 continues to increase beyond the level at which UBE = 0.7 V, the base of the transistor will 'absorb' the excess current. The TO-220 style BU406 transistor suggested here is capable of accepting base currents up to 4A. Using this charging indicator you have overcome the restrictions 2 and 3 mentioned above.

More aboutSchematics-Charging Battery Indicator

Power Suply DC 1.5-3.5 Volt Scheme

Posted by Erick Widyanto

The wonderful evening I will give tutorials schematics of power supply current 1.5 -35 volt DC voltage for you. May be useful to all of you who are want to learn to make this series.
 1A 1.5 volt to 35 volt dc Regulated Power Supply Circuit Schematic 1A 1.5 volt to 35 volt dc Regulated Power Supply Circuit Diagram

IC = LM317
P1 = 4.7K
R1 = 120R
C1 = 100nF - 63V
C2 = 1uF - 35V
C3 = 10uF - 35V
C4 = 2200uF - 35V
D1-D4 = 1N4007

  • Just add a suitable transformer (see table)
  • Great to power your projects and save money on batteries
  • Suitable as an adjustable power supply for experiments
  • Control DC motors, low voltage light bulbs, …

Specifications :
  • Preset any voltage between 1.5 and 35V
  • Very low ripple (80dB rejection)
  • Short-circuit, thermal and overload protection
  • Max input voltage : 28VAC or 40VDC
  • Max dissipation : 15W (with heatsink)
  • Dimensions : 52x52mm (2.1” x 2.1”)

Technical Specifications
  • Input Voltage = 40Vdc max Transformer
  • Output Voltage = 1.5V to 35Vdc
  • Output Current = 1.5 Amps max.
  • Power Dissipation = 15W max (cooled)

More aboutPower Suply DC 1.5-3.5 Volt Scheme