Vermes
Advanced Member level 4
It is a simple amplifier based on TDA7294. Interesting thing in this project is the design of wooden housing.
Assumptions:
The main assumption was to create device in an original housing which refers to the furniture of the old school and retain the simplicity of form and structure. Wooden body with stand and cover was entwined with brass plate which gave the contrast and sharpness.
Construction:
Size of the housing is A4, approximately 21x30x7cm. Such dimensions provide optimal placing of the components, small size of the construction, what more, it is robust and easy portable.
Housing consists of two 3mm plywood pieces, one of them is the base with feet, second is with wooden spacers makes the cover. The cover is wrapped in metal sheet, which in mounted to the spacers. Brass sheet was sanded along to get a uniform scratch, and then protected with a transparent varnish. The back part with connectors was made of a piece of plexiglass, painted and mounted to the base. Potentiometer mounted in the front part connects the base with the cover. Try to design your housing so that you can screw four screws into the feet of amplifier and catch spacers of the cover. Screw the whole so the screws are not visible. Remember about the cooling in the amplifier – holes on both sides of the device make air tunnel.
Electronics:
The device uses TDA7294, because it is not expensive but safe. The whole is powered from a 200W toroid transformer with filtering block, softstart and elements which stabilize ripple. Those components were placed on universal boards. It consists of a simple path through a choke, fuse, varistor and a relay. In addition, there is a small power supply turning on the relays of transformer and speakers. It operates on a simple system on NPN transistor, so that it is turned on with a delay, which eliminates noises. Cooling system is another important part of the project. Heat sink of power amplifiers is drilled, so air can flow through it. In addition, there is a fan with a simple system on thermistor. The fan activates at a certain temperature. LED under the knob slightly backlights it and indicates turning on the amplifier.
Pictures:
Link to original thread - Drewniak - prosty wzmacniacz TDA7294