ZX hardware - Building an Amplifier for the ZX Spectrum

Amplifier for the ZX Spectrum

Lately, more and more programs have been making full use of the BEEP command and offering excellent musical accompaniment.

If you use music-creation programs such as MUSIC MAKER, WHAM! THE MUSIC BOX or similar, you will need to amplify the sound from your computer.

The tone you get from the built-in (let’s call it that) speaker is anything but music you can enjoy. Below are two designs for building a simple, good-quality amplifier. They require very few components and only a little soldering skill.

First version

Parts list:

1. IC: LM380N-8
2. Ceramic capacitors (C2, C3, C5, C7)
3. Resistor (R1): 2.2 ohms
4. Electrolytic capacitors (C1, C4, C6)
5. Speaker (SP): 2 W, 4–8 ohms
6. Potentiometer (P1)

The ceramic capacitors are measured in nanofarads (nF), the electrolytic capacitors in microfarads (µF) and are rated at 16 V, and the potentiometer is a 10-kilohm logarithmic type.

The second version differs only in the type of integrated circuit: the second schematic uses an LM380N.

Which version you build depends solely on the type of IC. Transistors can also be used, but that makes construction more complicated.

You can power the amplifier from the computer’s power supply or from a separate source.

Be careful while working, and pay attention to the power-supply polarity. Incorrect polarity may prevent your masterpiece from working; reversing the supply polarity for either the computer or the amplifier can damage sensitive semiconductors.