Skip to main content

SL414 Vintage power amplifier IC

SL414 is combined audio preamplifier and power amplifier IC manufactured by National semiconductors in early days. This amplifier is designed to operate in 10V to a 20V range and deliver 3W (R.M.S) audio output power into the 7.5Ω load. The frequency bandwidth of this IC is between 30Hz to 18kHz and with the 8Ω load, it produces 0.5% T.H.D on 3W.

The most uncommon feature of this IC is its EP-10 package. This EP-10 package is common to most of the SL4xx series amplifiers and thanks to its inbuilt screw it is really easy to attach heat-sinks to these ICs.

EP-10 package of SL414 audio amplifier IC.

During our prototyping, we try several SL414 amplifiers and most of them give quite satisfactory results to us. Link to most stable SL414 design is available at the bottom of this article. As per our experiments, to archive best results it is mandatory to build this amplifier on PCB with screened wires. Also to get the good results to make sure to drive this amplifier with a regulated DC power supply. In our tests, we use an LM317 base PSU to drive this amplifier.

SL414 Amplifier prototype.

SL414 is quite hard to find and no longer manufactured by National (now TI). For those who having SL414’s can try our design/ PCB which is available at google drive.


Popular posts from this blog

Enable WebRTC on QtWebEngine for Raspberry Pi 3

WebRTC is a web technology to enable peer to peer communication in real-time. It mainly uses to create video conferencing and chat applications using web browsers. In this post, we describe how to enable this technology in QtWebEngine on Raspberry Pi 3 platform.

QtWebEngine is an embedded browser component which comes with the Qt framework. This component is based on Google Chromium browser and it supports most of the Chromium features including WebRTC. In PC, WebRTC applications run smoothly on QtWebEngine component. But in Raspberry Pi platform situation is different and none of the WebRTC application is work with the QtWebEngine. The only thing which we can see is a black box in an HTML5 video tag area. At the time of writing this problem exists in Qt version 5.6, 5.7 and 5.8.

BMP180 based USB atmospheric pressure monitor

We initially developed this USB atmospheric pressure monitor to study some operating characteristics of Bosch BMP180 sensor. BMP180 is a low-cost sensor for measuring barometric pressure and temperature. According to the datasheet this sensor can use to measure pressure ranging between 300hPa to 1100hPa. This sensor is introduced a couple of years back but still, it is popular due to lower cost and simplicity of its interface.

We did this unit to test the BMP180 sensor more accurately and to study its behaviors. This unit is based on PIC18F2550 microcontroller and the main reason to select this MCU is because of its built-in USB 2.0 interface.

To display sensor calibration data and it’s readings we did small windows application. This application display and plot temperature and pressure readings captured from the BMP180 sensor.

This unit is programmed to work as a USB HID device and no special device driver is required to use this device. We test this unit in Windows 10 environment.

Programmable light controller

The main objective of this project is to design a maintenance free and low-cost light which automatically turns on and off at the predetermined time of the day.

To meet the above requirement I designed this controller using ATmega8 MCU and DS1307 RTC. The driver stage of this light controller is intended to work with commonly available 7W LED modules.

The core component of this programmable light is ATmega8 low power CMOS microcontroller. The main reason to select this microcontroller is it’s lower cost and higher availability. Except for the above two reasons this microcontroller also bundled with a rich set of peripherals which including 23 GPIOs, 3 independent timers, Two-wire serial interface, EEPROM, etc.

Apart from ATmega8 microcontroller, this system uses DS1307 real time clock to maintain system time. Like ATmega8, DS1307 is also a very popular RTC in the market.

This controller is designed to work with a 24V DC power supply. The main reason to select 24V is that most of the…