Introduction: 12v DC to 20v AC Converter @ 45khz Output

By Trinity automation
About: Iam instrumentation and controls professional working in Emirates global aluminium (EGA) located at Dubai. I'm circuit designer and software developer by passion. Whatsapp (+91)9163954390

This design converts 12V DC input to 20V AC output @ 45Khz.

The design uses IC 555 as an astable multivibrator oscillating at a frequency of 45 khz. The IC 555 is powered with the same 12V DC power supply. The oscillator output is fed to a mosfet IRF840. The drain of the mosfet is connected to a small ferrite ring core with required turns of wire both in primary and secondary. The turns and other data is explained in construction.

The output of the transformer is an AC voltage at a high frequency.

Since it is high frequency of 45khz, the size of the transformer has reduced in size and weight.

Supplies

The spares list used for this project are as follows:

  1. IC 555 1no.
  2. Resistor 1K 1/4w 2 no.
  3. Capacitor 0.01uF 2 no.
  4. Resistor 330 ohm 1 watt 1 no.
  5. Resistor 10K 1/4 w 1 no.
  6. Mosfet IRF840 1 no.
  7. Heatsink for mosfet 1 no.
  8. Ferrite ring core id 1cm 1 no.
  9. Bread board 1 no.
  10. Wires 0.5 mm for wiring for transformer winding
  11. 12V DC SMPS power supply 1 no.

Step 1: Circuit Description

The circuit described here uses 12V DC as power input. Our agenda is to convert it to AC voltage and to step up the voltage. The DC voltage is fed to an oscillator. The oscillator output is fed to mosfet gate. The drain of the mosfet is connected to ferrite torroidal transformer. The output of the transformer is measured using a multimeter.

The circuit can be divided into three blocks. They are :

  1. Oscillator block: This block uses IC 555 in astable multivibrator mode. The IC 555 wired as shown in the main circuit oscillates at a frequency of 45Khz.
  2. Power switch: The power switch consists of mosfet IRF840. The gate of the mosfet is connected to 330ohm 1w resistor. This resistor is a current regulator. In case of mosfet short circuit or output short circuit, this resistor will limit current to mosfet gate, saving IC555 from damage.The gate of the mosfet is connected to 10K resistor to ground. This loop discharges the mosfet gate charge.
  3. Ferrite transformer: This transformer is wound on a ferrite core. ID 1mm. The primary of the ferrite is 12 turns wire. Secondary of the ferrite is 20 turns wire.


The circuit is tested as shown in youtube video.

Attachments

Step 2: Final Video