Guitar Circuit description:
This small amplifier was intended to be used in conjunction with an electric guitar to do some low power monitoring, mainly for practice, either via an incorporated small loudspeaker or headphones. The complete circuit, loudspeaker, batteries, input and output jacks can be encased in a small box having the dimensions of a packet of cigarettes, or it could be fitted also into a real packet of cigarettes like some ready-made units available on the market. This design can be used in three different ways: Loudspeaker amplifier: when powered by a 9V alkaline battery it can deliver about 1.5W peak output power to the incorporated loudspeaker. Headphone amplifier or low power loudspeaker amplifier: when powered by a 3V battery (2x1.5V cells) it can drive any headphone set type at a satisfactory output power level or deliver to the incorporated loudspeaker about 60mW of output power. This configuration is useful for saving battery costs. Fuzz-box: when powered by a 3V battery (2x1.5V cells) and having its output connected to a guitar amplifier input the circuit will behave as a good Fuzz-box, showing an output square wave with marked rounded corners, typical of valve-circuits output when driven into saturation.
Guitar amplifier circuit diagram:
Guitar amplifier partlist:
- R1__________22K 1/4W Resistor
- C1__________10µF 25V Electrolytic Capacitor
- C2__________100nF 63V Polyester or Ceramic Capacitor
- C3__________220µF 25V Electrolytic Capacitor
- IC1_________TDA7052 Audio power amplifier IC
- J1,J2_______6.3mm Stereo Jack sockets (switched)
- SPKR_______8 Ohm Loudspeaker (See Notes)
- B1_________9V PP3 Battery or 3V Battery (2 x 1.5V AA, AAA Cells in series etc.)
- Clip for PP3 Battery or socket for 2 x 1.5V AA or AAA Cells
Technical data:
- Max output power: 1.5W @ 9V supply - 8 Ohm load; 60mW @ 3V supply - 8 Ohm load
- Frequency response: Flat from 20Hz to 20kHz
- Total harmonic distortion @ 100mW output: 0.2%
- Max input voltage @ 3V supply: 8mV RMS
- Minimum input voltage for Fuzz-box operation: 18mV RMS @ 3V supply
- Current consumption @ 400mW and 9V supply: 200mA
- Current consumption @ 250mW and 9V supply: 150mA
- Current consumption @ 60mW and 3V supply: 80mA
- Quiescent current consumption: 6mA @ 9V, 4mA @ 3V supply
- Fuzz-box current consumption: 3mA @ 3V supply
