This kind of power supply is like a tiny adapter for your electronics.
It takes regular electricity usually high voltage and converts it to a lower safer voltage that your gadgets need.
Instead of using a bulky transformer, it uses special components like capacitors and diodes to do the job.
For example, a 30V 1A transformerless power supply would take high voltage and turn it into a steady flow of 30V at a maximum current of 1 amp which is perfect for powering smaller electronics.
This type of power supply is great for projects where you need a simple and affordable way to adjust the electricity for your gadgets.
However, transformerless power supplies have limitations including safety concerns due to the lack of isolation between the input and output circuits.
Circuit Working:
Parts List:
| Category | Item | Quantity |
|---|---|---|
| Resistors | 330k | 1 |
| 5Ω 2W | 1 | |
| 100k | 2 | |
| Capacitors | PPC 470nF 400V | 1 |
| PPC 560nF 700V | 1 | |
| Electrolytic 1µF 50V | 1 | |
| Electrolytic 2200µF 35V | 1 | |
| Electrolytic 22µF 400V | 1 | |
| Semiconductors | Thyristor SCR 5P4M | 1 |
| Fast diode BY127 | 1 | |
| Diode BA100 | 2 | |
| Zener 15V 1W | 2 |
This circuit for a transformerless power supply is intended for medium current applications.
During the negative half of the cycle capacitor C5 charges to the peak voltage of the network.
When the positive half wave arrives the thyristor opens and the electric charge stored in C5 transfers to C4.
The flow of electric charge through the thyristor begins when the voltage on C4 drops below a specified level set by zener diode D4 and D5.
As a result, the output voltage is not significantly affected by voltage fluctuations or changes in the output load.
The control signal for the thyristor is generated as follows: the main sinusoidal voltage is applied through capacitor C1 to zener diode D4 and D5 which limits the voltage to 30 Vpp.
The thyristor triggers at the leading edge of the limited voltage applied through C2 and R2.
Electrical characteristic of SCR 5P4M:
| Attributes | Symbol | Test Conditions | Min | Typ | Max | Unit | Remark |
|---|---|---|---|---|---|---|---|
| Repetitive Peak Reverse Current | IRRM | VRM=VRRM | 100 | μA | Tj=25∘C | ||
| VRM=VRRM | 2 | mA | Tj=125∘C | ||||
| Repetitive Peak Off-state Current | IDRM | VDM=VDRM | 100 | μA | Tj=25∘C | ||
| VDM=VDRM | 2 | mA | Tj=125∘C | ||||
| Critical Rate Rise of Off-state Voltage | dV/dt | Tj=125∘C | 40 | V/μs | VDM=2/3 VDRM | ||
| On-state Voltage | VTM | ITM=10 A | 1.4 | V | |||
| Gate-trigger Current | IGT | RL=100 Ω | 10 | mA | |||
| VDM=6 V | V | ||||||
| Gate-trigger Voltage | VGT | VDM=6 V | 1.5 | V | |||
| RL=100 Ω | V | ||||||
| Gate Non-trigger Voltage | VGD | Tj=125∘C | 0.2 | V | VDM=1/2 VDROM | ||
| Holding Current | IH | ITM=10 A | 6 | mA | VDM=24 V | ||
| Circuit Commuted Turn-off Time | tq | VR≥25 V | 50 | μs | ITM=5 A | $V_{DM}=2/3~V_{DRM},\) diRdt /= 15 A/μς$ | |
| Tj=125∘C | μs | dVD/dt=10 V/μS | |||||
| Thermal Resistance | Rm(j-c) | Junction to case DC | 3 | °C/W | |||
| Rth(j-a) | Junction to ambient DC | 65 | °C/W |
How to Build:
To build a Simple Transformerless Power Supply 30V 1Amp Circuit follow the below mentioned connections steps:
Gather Components:
- Collect all the required components for the circuit, including capacitors, resistors, thyristor and zener diode.
Circuit Design:
- Follow the circuit diagram provided earlier to design the circuit on a breadboard or a PCB.
Capacitor Connections:
- Connect capacitor C1 in series with the main sinusoidal voltage source.
- Connect capacitor C2 in parallel with C1 and in series with resistor R1.
Thyristor Connection:
- Connect the gate of the thyristor to the junction of C2 and R2.
- Connect the anode of the thyristor to the positive terminal of capacitor C5 and the cathode to the output terminal.
Zener Diode Connection:
- Connect zener diode D4 and D5 in parallel with C2 and R1.
Final Checks:
- Double check all connections and ensure that there are no short circuits or incorrect connections.
Power Up:
- Apply power to the circuit and check for proper functioning.
- Use appropriate safety measures when working with high voltage circuits.
- Test the output voltage of the circuit under various load conditions to verify its stability and performance.
Note:
- Please note that building and working with high voltage circuits can be dangerous.
- Ensure you have the necessary knowledge and take appropriate safety precautions.
Conclusion:
To conclude, a transformerless power supply rated at 30V 1A offers a compact and cost effective solution for low power electronic applications.
However, due to the lack of isolation between input and output it is essential to use these supplies with caution and ensure proper safety measures are in place.