Low power audio amplifiers.
There are a multitude of low power amplifiers using integrated circuits,
I will show some quite common, easy to make and generally low cost.
Most of these amplifiers are used by televisions, test and measurement equipment, old modems, etc.
At present there is talk of sound equipment of “10,000 Watts PMPO” or more.
Then someone may think that a 20 watt amplifier per channel is low power when in fact it is not, because here we talk about real power or RMS.
And you should know that PMPO is not a real electronic measure .
Low power amplifier projects are 1W, 2W or less than 10 watts.
2.5W Amplifier Using LM380N
First I will present the popular LM380, widely used in televisions, communication radios, measuring equipment, modem, etc.
This integrated circuit is very flexible for the voltage, according to the manufacturer works well from 10 to 22 volts,
delivering a power of up to 2.5 watts. I use it in projects for 12 volts.
LM380 connection drawing:
LM386 <1W amplifier
This amplifier is similar to the LM380 but is much less power, reaching 1 watt the LM386N-4,
the operating voltage ranges from 4 to 12 volts (LM386N-1, LM386N-3, LM386M-1, LM386MM-1)
or from 5 to 18 volts the LM386N-4.
Diagram of the amplifier with LM386:
The gain of this amplifier is adjusted between pins 1 and 8
disconnected approximately 26dB, and with an electrolytic capacitor between the tips up to 46dB. (10uF, positive pin1)
LM386 connection drawing:
Most versions of the LM386 are of the order of 125 mW.
Used quite a lot as an amplifier for hearing aids or as an output in error indicators, alert tones and “buzzer”.
TDA7235 integrated circuit from 1.25 to 4W
The TDA7235 is widely used in televisions, with heat sink can be used as a 4-watt amplifier.
The voltage is surprisingly flexible, it can be used from 1.8 volts to 24.
Connection drawing of the TDA7235:
2W TDA7267 integrated circuit
The TDA7267 is specially designed for televisions, with gain set at 32dB.
Although the voltage is not as flexible as the previous one, it can work from 4.5V to 18V.
With pin 3 (SVR) grounded the integrated circuit is at rest (stand-by)
Connection drawing of the TDA7267:
Integrated circuit TDA2822M Stereo 8 Pin
This integrated circuit in addition to the versatile with the power supply (1.8V to 15V), is double (stereo).
Being the ideal for projects or portable applications, trying not to exceed 1 watt per channel.
Connection drawing of the TDA2822M:
The UTC2822H amplifier, the D2822N and the TDA2822M are exactly the same in connections and the only difference found is that the UTC2822H can only work from 1.8V to 6V, and supports a maximum of 9 volts. While the D2822N does work from 1.8V to 15V.
There is also the TDA2822 which is 16 pins.
TDA2822 16-pin integrated circuit.
This integrated circuit can be used from 3 to 15 Volts, it can handle a maximum of 4 watts
(2W x 2) with heat sink.
The electronic features are similar to the 8-pin TDA2822M amplifier, but used from 3 volts.
Connection drawing of the 16-pin TDA2822:
Both for this amplifier TDA2822 and for all others we must take into account a good ground connection to avoid oscillations that could damage them or produce unwanted noise.