Sinclair Spectrum128 Keypad

Posted on Feb 6, 2014

The features available via the keypad are mentioned in the Spectrum128 Introduction Manual that was included with every machine sold. The service manual for the Spectrum128 is aimed at repair technicians and describes the circuitry and communications protocol used by the keypad. Extracts from both of these documents are reproduced below.

Click here to download the full size of the above Circuit.

Visit page

Leave Comment

characters left:

Related Circuits

12V Battery Checker Circuit

This is a 12V battery checker circuit that uses 3 LEDs that light up at their respective voltages. The red LED lights up when the battery voltage is between 8 to 10V, the orange one at voltages...

230V Flasher Circuit diagram

This circuit operates with 230v. you can use this circuit to decorate your parties. I think this will be a wonderful circuit to you all. Here DIAC ER 900 and Triac BTW 11-400.

Automatic light activated switch circuit

The circuit can be used for switching OFF a particular lamp or group of lamps in response to the varying ambient light levels. The unit once built can be used for switching OFF a lamp when dawn...

BC548 Heat Sensor Diagram Circuit

Heat sensor circuit can be used to control any device using heat sensor. In this circuit a thermistor and a resistance is connected in series. This arrangement makes a potential divider circuit....

GSM CELL PHONE JAMMER SCHEMATIC

A wonderful diy gsm jammer or cellular mobile phone jammer schematic diagram for use only in GSM1900 with frequency from 1930 MHz to 1990 MHz. The GSM1900 cellular cell phone network is made use of...

Biosensor circuit

This week was spent completing a number of different objectives. Firstly, the software was downloaded to design the schematic for the circuit to be translated onto a PCB. Much of the week was spent...

Instrumentation circuit

The mechanical chassis prototype, as can be seen from the image on the left, was made using two materials: foam and aluminium. Foam was chosen due to its easy manipulation and aluminium due to its...

Hum Circuit

Although our kit utilizes an off-the-shelf microcontroller (AtMega328P-PU based Arduino), we additionally designed a simplified version. This allows other collaborators and students to potentially...

New Circuits

Zero consumption Anti-theft High power Code Switch for E-Bike Batteries

This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
Ultrasonic distance finder circuit

The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Simple Metal detector circuit with CD4030

Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Fully automatic watering circuit for flower pots

Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
Simple deep searching metal detector circuit

The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
Sub-Harmonic Bass Converter for Electric Guitars

The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
Echo Depth Sounding Sonar for Boats

In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
100W HiFi Audio Amplifier Circuit

This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
Plant-Pot Water Level Indicator Circuit

A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....