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Audio Description – Course 7, Non Sinusoidal Transformer Core Testing
Metglas / Nanocrystal core

– Clip 1 Introduction – Clip 2 Course Description – Clip 3 Test Parameters – Clip 4 Test Equipment – Clip 5 Overview – Clip 6 BD437G – Clip 7 BD135-16 – Clip 8 2SC5707 – Clip 9 2N5681 – Clip 10 2SD882 – Clip 11 2N3055 – Clip 12 BUF644 – Clip 13 Calculation 1 – Clip 14 Summary – Clip 15 Load, No-Load – Clip 16 Wave Characteristic BD437G SG – Clip 17 BD135-16 SG – Clip 18 2SC5707 SG – Clip 19 2N5681 SG – Clip 20 2SD882 SG – Clip 21 2N3055 SG – Clip 22 BUF644 SG – Clip 23 Calculation 2 – Clip 24 Conclusion – Clip 25 End of Part 3

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In our third test serie we look at the Metglas / Nanocrystal core

We test with the evaluation board 7 transistors. Test is conducted in self-oscillation and signal driven from a signal generator. We also look at the Load, No-Load values.

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Course Description

Non Sinusoidal Transformer Core Testing
for Metglas / Nanocrystal

– Compare a fixed power consumption to the light level output
– Use many Transistors for the test
– Apply Load, No-Load measurement
– Compare self-oscillation to signal generator driven transistors

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Test Parameters

1. One evaluation board with transistors and LED array
2. Metglas / Nanocrystal Core

 

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Test Equipment
Tools

– EA, PS 2000 B, 84 V 5 A, Power supply
– Agilent/Keysight InfiniVision 3000 Series oscilloscope DSOX3014A
– External 19 Inch Monitor for Oscilloscope
– Gossen Mastersix light meter
– Agilent 34450 A 5.5 digit Benchtop DMM

 

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We integrate our measurements into the formula

Core, Metglas / Nanocrystal, 120 m SWG22 and 2 X 1.2m 16/02 EQ wire
Reference power value 400 mV and 0.030 A = 0.012 Watt
Load: 5 LEDs in series, 3 Volt 20 mA = 15 Volt and 100 mA = 1.5 Watt

1. BD437G, NPN TRANSISTOR, 26 Hz, 1300 LX
2. BD135-16, NPN TRANSISTOR, 36KHz, 800 LX
3. 2SC5707-E, NPN TRANSISTOR, 31 Hz, 1100 LX
4. 2N5681, NPN TRANSITOR, 74 Hz, 520 LX
5. 2SD882 , NPN TRANSISTOR, 25 Hz, 1800 LX
6. 2N3055, NPN TRANSISTOR, 31 Hz, 1400 LX
7. BUF644, NPN TRANSISTOR, 83Hz, 370 LX

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Summary

The property of the Metgas / Nanocrystal core becomes in the self-oscillation
mode apparent.
The back EMF is almost fully absorbed by the load so that no free resonance
can occur. Only at very low frequency self –oscillation is possible. The Overdrive
is when no resistance is at the base than all current can be drawn from the
source to the load wsiht increased frequency. This core Is perfect for utilising
impulse power and high current. It is also the core of choice for high frequency
and high voltage applications. The performance of the transistors is reflected
from all previous tests.

We move on to frequency driven via the signal generator and Load, No- Load test

 

 

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We integrate our measurements into the formula

Source Voltage , 400 mV
Square wave, 50%, 5 Volt, High Z

1. BD437G, NPN TRANSISTOR, 26 mA, 0.0104 Watt, 22 KHz, 1800 LX
2. BD135-16, NPN TRANSISTOR, 32 mA, 0.0128 Watt, 79 KHz, 1100 LX
3. 2SC5707-E, NPN TRANSISTOR, 36 mA, 0.0144 Watt, 46 KHz, 2000 LX
4. 2N5681, NPN TRANSITOR, 16 mA, 0.0064 Watt, 37 KHz, 370 LX
5. 2SD882 , NPN TRANSISTOR, 34 mA, 0.0136 Watt, 43 KHz, 2000 LX
6. 2N3055, NPN TRANSISTOR, 26 mA, 0.0104 Watt, 31 KHz, 1200 LX
7. BUF644, NPN TRANSISTOR, 11 mA, 0.0044 Watt, 42 Hz, 750 LX

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Conclusion

Under frequency driven High Z from a signal generator with the Metglas / Nanocrystal
Core we have a much better performance as with self-oscillation. We notice that the
transistors show the same pattern but also that the No-Load test is frequency depended.
We have for one transistor no difference between load and No-Load. The magnetisation of
the secondary winding is costing current. A clear indication how much the load requires
differs with frequency and transistor. I recommend to use a bifilar primary coil. I noticed
that a higher voltage level is required but the output and voltage increase on the
secondary is much higher as well. This core has very interesting properties but does
not match our requirements for an ultra-efficient LED driver. When using high voltage
and high frequency this core will shine. I will pick up this test in the future.
We move on to the smaller cores, Ferrite N30.

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The End Part 3
Non Sinusoidal Transformer Core Testing

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