How to make the simplest amplifier

The need for a makeshift booster happens regularly to guitarists. Concert set, as a rule, stands in the rehearsal room. It weighs a lot, each time to carry uncomfortable, hence the desire to collect something for home rehearsals. But at concerts like this amplifier can also be used. The output power reaches 3.5-4 W at a fairly high sound quality.

You will need

• - power supply from an old tube receiver or radiograms;
• - electron tube and socket thereto;
• - variable resistance 220 ohms;
• - the input Jack;
• - mounting wire;
• - a piece of plywood with a thickness of 3-5 mm;
• - fine brass mesh or radiating;
• - output transformer from a vacuum tube receiver or TV
• - housing cover from the old CD or DVD drive;
• - an electric drill;
• jig - saw;
• - soldering iron, rosin, tin.

Instruction

1. Body cover mark and drill out the holes for the socket and for mounting the transformer TVZ or the like. Install the components on the lid of the chassis. In its lateral wall socket hook up input connector, variable resistor, which is the volume control of the amplifier. If the power supply is missing the switch and install it into the side wall. Try to make all of the mentioned elements were on one side of the chassis. If the items that you have, have the fasteners, make them the necessary holes.
2. Mount on the chassis of the radio according to attached chart. While on the lamp insert. Keep in mind that in the anode circuit of the lamp turns on the high impedance winding of the output transformer.
3. On a separate wooden or plywood panels, secure the speakers, having cut holes for them. It can be 2 speakers of 1.5 W from the television or gramophone. Maybe 1 speaker 3-4 watts from a tube radio. Speakers can be of different shapes. You only need to provide a total power of not less than 3 W and the total resistance in a parallel inclusion of 3-8 Ohms.
4. If desired, protect the dynamics of fine brass mesh or radiomenu. If you use two parallel dynamics, they must be spaserovat. Pick up this integration, in which the diffusers will be drawn or pushed out simultaneously, the circuit to apply a constant current to a small voltage (e.g. from batteries)
5. Connect the power supply unit, amplifier and speakers so that the intensity apply an alternating voltage of 6.3 V. connect the DC plate voltage in the 210-300 V and negative connect to the body chassis. Connect to the output (low impedance) winding of the output transformer dynamics. Insert the lamp into the panel. Turn on the amplifier to the network. If it is assembled correctly, then after two or three minutes of warm-up it will be ready to work. If from the speakers you will hear a loud buzzing sound, then you need to reverse the wires connecting them to the output transformer.
6. Using a guitar cable to connect the amplifier with the electric guitar. Volume control of the amplifier gain the greatest power In the guitar sound.. the controller must be set on maximum volume. This amp typically does not require additional adjustments and settings.
7. Plywood make the body. The power supply can be placed in the lower part and the chassis of the amplifier over it. There are other layout options. If desired, you can decorate the enclosure with leatherette, mount a handle on it for carrying etc.