Introduction: Small AC to DC Converter
Created By: Haotian Ye
The small AC to DC Voltage Converter project uses four diodes to make one bridge rectifier to transfer AC power to DC power. Also, we use capacitors to remove ripples in the circuit. After we transfer from AC power to DC power, we need to use one 5v voltage regulator to give 5v DC output from 12 v DC output.
Parts You Will Need:
Transformer 12VAC 20VA (Lee's ID:10641)
IN4001 Diode (Lee's ID:796)
16V 1000UF Electrolytic Cap (Lee's ID:867)
50V 0.1UF Ceramic Cap (Lee's ID:8175)
50V 0.22UF Ceramic Cap (Lee's ID:8174)
Breadboard (Lee's ID:10686)
Jumper Wires (Lee's ID: 21802)
Mini Voltage Display (Lee's ID:1265)
IC Regulator 7805 +5V 1A (Lee's ID:7115)
Step 1: Choose the Transformer
In this project we choose a 12VAC 20VA transformer with screws at the bottom. In order to power the circuit with this transformer, we have to screw the jumer wire pin inside and plug to the breadboard. Because this is an AC power supply, the positive and negative side does not matter.
Step 2: Build the Bridge Rectifier With One Capacitor in Parallel With It
In this step, we build an bridge rectifier which make up of four 1N4001 diodes. Then, we parallel this rectifier with an 1000uf parallel to remove some ripple. The thing need to be noticed is the polarity, remember the silver line on the diode indicates that it is a cathode terminal. After finishing building, please use mini voltage display to test the voltage across the capacitor. It will give you an around 18v DC power.
Step 3: Add the Voltage Regulator to Give 5v DC Output
In this step, we need to use the 5v IC Regulator, one 0.1uf ceramic capacitor, one 0.22uf ceramic capacitor and one 1000uf electrolytic capacitor. For the IC regulator, with the lead on the bottom, the left is input, the middle is ground and the right is output. After finishing building the circuit, you can use voltage display to test the output voltage by paralleling it with the last 1000uf capacitor. You will see the output is 5v DC.
Step 4: Future Improvement
In this project, we can only have a 5v DC output. However, we can try to figure out output any voltage from 0v to 12v DC. This can be solved by replacing Voltage regulator 7805 with a variable voltage regulator LM317.
Question 2 years ago on Step 4
Hi, can I ask a question?
Can you explain how all the capacitors work, and what are their mission in this circuit?
Why are they 1000uF capacitors? Can I use another value for them?
Answer 2 years ago
Capacitors serve as an energy storage element, they have a smoothing or "filtering" effect as they absorb/dissipate charge depending on the conditions of the nodes they connect. The 1000uF value describes the "capacity" they have for storing charge. There will be a minimum value required to smooth out the spikes coming off the rectifier section (to a degree, it'll never be perfect) but exceeding this value doesn't get you much. When selecting a capacitor value, keep in mind that standard manufacturer tolerance is +/- 20%, thus your selected value should be at least 1.25x the minimum value. If you want to be as precise as possible, there are plenty of resources online to help you calculate the capacitance value you'd need