Boost Converter 12V to 120V DC Step-Up Circuit raises a 12V DC input to 120V DC output; it helps convert voltage levels when required and delivers a high 120V output from a 12V source.
Circuit is good for using high voltage from low voltage like battery and output powers to about 100 watts.
Here, circuit has two parts first is simple inverter and second is rectifier and filter.
IC 555 timer runs at 100Hz as astable multivibrator and it connects to clock input of CD 4013 flip-flop IC and also circuit works by switching with IC 555, CD 4013 flip-flop, power transistors and step-up transformer to raise the voltage.
Circuit Working:

Parts List:
| Components | Values | Quantity |
|---|---|---|
| Resistors (All resistors are 1/4 watt unless specified) | 18k | 1 |
| 3.3k | 1 | |
| 1k | 1 | |
| 1.5k | 2 | |
| Preset 100k | 1 | |
| Capacitors | Ceramic 330nF | 1 |
| PPC 220nF 250V | 1 | |
| Electrolytic 1000µF 25V | 1 | |
| Electrolytic 2200µF 250V | 1 | |
| Semiconductors | Transistor MJ3001 | 2 |
| 9-0-9V /120V / 3A Mains Transformer | 1 | |
| 1N5408 Bridge Rectifier Diodes | 4 |
Boost Converter 12V to 120V DC work like this:
Oscillator Stage IC1 555 Timer:
IC1, a 555 timer, works as an astable multivibrator and generates clock pulses to control the flip-flop IC2 (CD4013).
Resistors VR1 and R1, along with capacitor C1, determine its operating speed.
Flip-Flop CD 4013 IC2:
CD 4013 flip-flop cuts frequency from IC1 555 timer in half and then make pulses to turn power transistors Q1 and Q2 ON and OFF.
Power Transistors MJ3001:
Q1 and Q2 act as switches and they control current in transformer primary side and then make magnetic field to raise voltage in transformer secondary.
Step-Up Transformer:
Transformer 9-0-9V raise voltage from 12V AC to about 120V AC.
Rectification and Filtering:
Bridge rectifier D1 changes AC to DC and capacitors C3 and C4 smooth output to steady 120V DC.
How to Build:
To build a Boost Converter 12V to 120V DC Step-Up Circuit follow the below mentioned steps for connections:
- First, get all parts from circuit diagram
IC1 555 timer:
- Next, pin 1 connects to GND and pin 2 connects to pin 6
- Then pin 3 connects to pin 3 of IC2 through resistor R4
- Now pin 4 & 8 go to +12V supply and then VR1 resistor connect between pin 7 and +12V
- Also, R1 resistor connect between pin 7 and pin 6
- After that, C1 capacitor connect between pin 2 & 6 and GND
- R2 resistor from pin 3 goes to GND and C2 capacitor positive go to +12V and negative go to GND
IC2 CD 4013 flip-flop:
- Next, pin 1 go to base of Q1 through resistor R4
- Now pin 4, 6, 7 go to GND
- Then pin 2 & 5 go to base of Q2 through resistor R5
- Lastly, pin 14 connects to +12V supply
Transistors Q1 and Q2:
- First, collector of Q1 goes to primary transformer wire and emitter of Q1 connects to emitter of Q2
- Next, primary center wire of transformer goes to +12V
- Then collector of Q2 connects to other primary transformer wire and transformer secondary wires goes to bridge rectifier D1 to D4 ends
- Also, other two bridge rectifier ends connect to 120V DC output
- Finally, capacitors C3 & C4 connect across bridge rectifier output
Conclusion:
To conclude, this Boost Converter 12V to 120V DC Step-Up Circuit raises 12V DC to steady 120V DC using 555 timer, CD4013 flip-flop, power transistors and transformer.
Also, it is good for small power, emergency lights and portable high voltage devices.
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