Powering 25W Loads: CMOS to 12V Circuit Design

Description

The circuit presented below is intended for utilization alongside the referenced bi-directional lamp sequencer, also located on this same page. Additional transistors are employed to elevate the current delivered by the 74HCT138 decoder, allowing for the operation of twelve 25-watt lamps. A 6.8-volt/1-watt zener diode is incorporated in series with the ground connection of all CMOS integrated circuits – namely the 74HC14, CD4516, and 74HC138 instances – to ensure the total voltage across these devices remains approximately 5.2 volts, resulting in outputs transitioning from +12 volts to roughly +7 volts when selected. These integrated circuits, commonly known as microchips, are complex semiconductor devices containing multiple electronic circuits fabricated on a small silicon chip. They are designed to perform specific functions, such as logic operations, data processing, or timing control. The selection of these specific chips – 74HC14, CD4516, and 74HC138 – ensures compatibility with the overall sequencing system. The utilization of these ICs allows for precise control of the lamp outputs.

74HC14

The 74HC14 is a versatile quadruple NAND gate integrated circuit. It consists of four independent NAND gates, each implementing the basic NAND logic function. This integrated circuit is commonly used in digital logic circuits, digital timers, and other applications requiring boolean logic operations. It offers excellent noise immunity and high speed performance. It is a key component in the sequencer's logic control.

CD4516

The CD4516 is a six-input multiplexer integrated circuit. It allows selecting one of six inputs and routing it to a single output. This integrated circuit is frequently used in data selection, analog-to-digital conversion, and digital logic circuits. The CD4516 is essential for managing the control signals within the sequencing system, directing power to specific lamp sets.

74HC138

The 74HC138 is a quadruple decoder integrated circuit. It converts a single binary input into four output signals, allowing for the selection of one of four output lines. These integrated circuits are commonly utilized in digital logic, address decoding, and control systems. The 74HC138 provides the core decoding functionality for the lamp sequencing system, determining which lamps are activated based on input signals.

Circuit diagram