An SMPS halogen lamp circuit mostly needs a transformer to work and in this post we explain a new type of transformer using a switching power supply.
Also, the circuit is simpler than old transformers and it can work with other bulbs too but only if they do not use RF (radio waves), furthermore, this new design also saves energy.
What is a SMPS Halogen Lamp Circuit:
A power supply circuit made to safely power halogen lamps is called SMPS (Switched Mode Power Supply) and these halogen lamps need steady, controlled power and run at high heat.
Hence, SMPS gives fixed voltage or current to turn on the halogen lamp properly.
Circuit Design and Working:
Parts List:
| Components | Values | Quantity |
|---|---|---|
| Resistors (All resistors are 1/4 watt unless specified) | ||
| 33k 4W | 1 | |
| 47k | 1 | |
| 47Ω 2W | 1 | |
| 15Ω | 2 | |
| Capacitors | ||
| PPC 470nF 400V | 2 | |
| PPC 1μF 250V | 2 | |
| PPC 330pF | 1 | |
| PPC 100nF 25V | 1 | |
| PPC 2.2nF 1kV | 1 | |
| Electrolytic 220μF 25V | 1 | |
| Semiconductors | ||
| Diode 1N4007 | 4 | |
| Schottky Diode BA159 | 1 | |
| MOSFET IRF840 | 2 | |
| IC IR2153 | 1 | |
| EMI Filter | 1 |
First, the circuit uses MOSFETs in half-bridge style and the IR2153 chip drives them and this chip has an RC oscillator and a floating driver for the top MOSFET.
Transformer from mains give around 107V when working at about 50 kHz frequency.
Formulas and Calculations:
Below is the voltage formula:
Uef = (Uvst − 2) × 0.5 × √(t − 2 × deadtime / t)
where:
- Uef is a final voltage coming out which is the effective voltage.
- Uvst is goal voltage SMPS try to reach or keep.
- t is time in switching maybe from timing part.
- Deadtime is short pause time in SMPS switch cycle.
- The part (t − 2 × deadtime / t) shows how voltage change with timing.
- The 0.5 number is scaling to fix voltage output.
Transformer Tr1:
This transformer use ferrite core EE or EI type and it come from old computer power supply like AT or ATX.
The core size should be around 90 to 140 mm² and how many wire turns needed depends on bulb it needs.
So, we wind the coil like this to reduce magnetic loss:
20 turns bottom + 20 turns top is the secondary and 40 turns in primary for normal ATX.
Transformation Ratio:
If input is 230V and we want 107V at transformer primary then:
Ratio = 107V / 11.5V = 9.304
If bulb is 12V but works good at 11.5V and secondary have 4 turns then:
Primary = 9.304 × 4t = 37t
Be sure winding is correct for best working.
Safety Warning:
Always be very careful because almost all parts of this circuit connect to mains voltage, which is very high.
Also, if we do not make transformer Tr1 properly, dangerous mains voltage can go to the output.
So always follow safety rules while making or using this halogen transformer and do all steps very carefully to keep it safe and working properly.
Below is the guide to make the transformer:
Circuit Design:
Make circuit diagram using instructions from start and put IR2153 IC, pulse transformer Tr1 and half-bridge with MOSFETs.
Check if circuit board gets enough space to fit all parts and connect them good.
Transformer Construction:
Also, if the ferrite core is not the right shape, cut and shape it same like the transformer design.
When winding primary coil do like 20 turns under and 20 turns above the secondary and follow the way it say.
First, remove all secondary and top part of old primary winding.
Now wind new secondary coil and use correct number of turns for required bulb voltage, before putting core back, make sure we seal all windings properly.
Circuit Assembling:
Solder all parts on circuit board same like the layout and design and make half-bridge connection from IR2153 IC to MOSFETs.
Also, connect capacitor divider and diode bridge same like in circuit diagram.
Before giving power, check that the transformer is connected with correct polarity.
Use multimeter to test voltage at many points in circuit if something is not working.
Overall, remember if output is not good then try changing number of turns on transformer or other settings.
Since, problem take place than use oscilloscope and multimeter to check and fix the issue.
Conclusion:
Always be careful while building or using SMPS Halogen Lamp Circuit because halogen bulbs can get very hot, it is important to follow all safety rules and laws.
Better to follow design rules and safety steps to stay safe.