This is a compact, easy to build amplifier that uses one IC only but delivers 40 watts of audio power. It is ideal for amplifying audio from your mobile CD player or iPod. The chip being used here is the TDA1514 originally brought to the market by Phillips/Valvo. The best characteristics of this chip is its high output power and robustness. It is available in a 9-pin SIL plastic package with a metal mount.
Its package has a heat resistance of less than 1.5K/W. This means that the heatsink must have a heat resistance of only 3.8K/W when the chip reaches its maximum power dissipation of 19W (at Ub = +/-27.5V, Tu = 500C).
One can see from the diagram that only a handful of passive elements are needed to build the chip into a powerful audio amplifier. The power supply as supplied must be able to deliver a current of at least 3 amperes. The standby current consumption is about 60 mA. The supply voltage must never go beyond 27.5 volts!
In building the circuit, keep the wires to the power supply and outputs as short as possible. The resistos R4 and R5 set the voltage gain at the feedback which, in this case, is between 20 and 46 dB.
For a single channel amplifier(mono), a 80 VA transformer (T1) should be sufficient. If you construct two channels (or stereo) amps, 120 VA is recommended. Capacitors Cx and Cy should be at least 4.700uF rated at 35V. It can be up to 10.000uF.
Capacitors twice as large discharge slower giving better peak power potential resulting to better power output. Feel free to increase the capacitance but take note that you may not get much additional benefit for the price involved. Make sure they are connected the right way around too or they will blow and cause injury.
A 0.25 mA fuse (F1) should be installed. If using toroidal transformer, the fuse must be a time delay (slow blow) variant. Be sure to correctly earth the supply and any metal casing around it. The components on the earth and ground connections (Dx, Dy, Rx, Cz) form a loop breaker. This is recommended because it can eliminate those troublesome earth loops. Rx is a 5 W or better wirewound resistor. The Cz capacitor must be rated for 250 V AC.
Do NOT use a 250 V DC capacitor for Cz as it would fail if there ever was a fault causing mains current to flow to earth. Dx and Dy are rated at 250 V/ 1 A. If your local rules and regulations prohibit constructing this, omit all these components and connect the earth to ground but NEVER disconnect the earth lead… it could save your life or somebody elses!
Constructing the power supply for this amplifier is simple. As shown on the schematic above you need to wire up a 18-0-18 (center tapped) transformer in order to get the recommended +/- 25V. Be very careful since this construction involves mains wiring.
MAINS VOLTAGE IS VERY DANGEROUS. DO NOT WIRE IT UNLESS YOU ARE QUALIFIED. DEATH OR SERIOUS INJURY MAY RESULT.
Parts Placement Layout for mono 40 W amplifier
Printed Circuit Layout for stereo 2×40 W amplifier
Parts Placement Layout for stereo 2×40 W amplifier