Showing posts from December, 2016

How to make a DC power supply for your amplifier

Hello, today I will show you how to make a DC power supply for your amplifier project. An audio amplifier normally needs DC power supply to feed it so you need to know how to make it if you want to make a good amplifier. Now, let's start. 1. Find your amplifier's recommended voltage. I use TA2024 amplifier board, the amp board recommends voltage is 8.5 - 13.2 volts so I need a DC power supply that output voltage does not exceed 13.2 volts. 2 Find the right transformer for your project. When you convert AC to DC with full bridge diode rectifier, the DC voltage increase around 1.4142 - 0.6 volts from an AC input when DC output doesn't connect to a load. I found the formula on the internet and it is AC x 1.4142 only but it was not same as I measured because the DC output voltage decreases around 0.6 volts. The transformer on the above picture provide 9.65 volts AC without connecting to a load, the voltage will drop when you connect to a load. So t

Automatic night light switch project

Hello, today I'm going to show you how to make automatic night light switch. This circuit is easy to make and uses few electronic components. This automatic night light switch project makes you save your electricity bill and makes your light bulb life longer. The circuit uses 5 volts power supply so you can use old USB cell phone charger as a power source or you can use any 5 volts adapter that rate at least 100 mAh.  Electronic components list: BD139 npn transistor = 1 BD140 pnp transistor = 1 100 kilo-ohms resistor = 2 5Volts@100 mAh adapter 1 kilo-ohms resistor = 1 Led = 1 ( you can remove 1 kilo-ohms resistor and LED if you don't need LED indicator) 1 LDR (light dependent resistor) = 1 5 volts Relay = 1 All resistor are 1/4 watts rating Full wiring diagram Circuit explains: BD 140 is a PNP transistor that amplifies small current from 2 x 100 kilo-ohms resistor and sending current to  BD 139 NPN transistor Base (B) and amplifies current