Automotive grade

What's New at Firstohm Autumn 2015



What's New at Firstohm
Autumn 2015


20150921 102253There is everlasting debate when it comes to MELF 0204 vs. CHIP 1206. This round in the “Do You Know” section, Firstohm will present anti-surge capability comparison conducted by its own engineer team. And we bet that you do not know this – other than special resistors such as anti-surge resistors, high voltage resistors, or high power resistors, Firstohm also prides itself in “fusion” resistors, or those of multiple functions.
Looking for an anti-surge resistor that would short-circuit (or fuse) when passing current is at certain level? You will be interested in our short-circuit protection resistor (SCP series) or anti-surge wirewound resistor (SWA/SWM series).
In this latest edition of Firstohm e-newsletters, you would have a peek into our ultra low resistance fusible resistor, which, along with a surge absorber, can form an effective surge-protection mechanism. Also, you wouldn't want to miss our latest non-resistor innovation - surface mount MELF fuse.
As always, we are grateful for your time. Any questions or comments, do contact us!


Firstohm In Action


10/06/2015 ~ 10/09/2015 (TAITRONICS 2015)Nangang Exhibition Center, Booth J0812.

20150921 102912
1/13/2016 ~ 1/15/2016 (Nepcon Japan 2016)Booth EM2-0006.

20150921 102836

Do You Know


- MELF 0204 vs. CHIP 1206 -

Previously, we shared with you the difference between the two from mechanical as well as from electrical perspectives. As importance of component's anti-surge capability grows along with the increasing intricacy of circuit designs, we conducted further experiments and found that 0204 MELF resistors are better than 1206 CHIP resistor in both resistor structure and resistance variation when sustaining prolonged surge energy.

Comparison 1 -
Firstohm SRM204T and anti-surge 1206 CHIP resistor by company V1 connected in series,AC12.25W applied individually:

20151005 01

Comparison 2 -
Firstohm SRM204T and anti-surge 1206 CHIP resistor by company V2 connected in series,AC20.25W applied individually:

20151005 02


Structure of CHIP resistor is prone to damage as the heat induced by surge energy tends to accumulate on one-side of CHIP resistor surface, rendering CHIP resistor relatively unreliable against impact of prolonged surge energy (approximately 0.1s-0.8s, with 10w-81w power).

Through this experiment, users should be reminded to choose the most suitable types of anti-surge resistors based on the designed circuit functionality in order to effectively protect the circuitry.

[Note: Excerpt above is provided for reference only. Please check with us for the detail information, including assumptions behind the entire experiment.]

New On the Block


(1) Ultra Low Resistance Fusible Resistor (ULF) 

20151005 03ULF series, as the name suggested, has very low resistance and functions as fuse. As depicted in the simplified graphic, ULF used together with other SPD's (or Surge Protection Device), the formed surge protection mechanism can sustain high surge voltage. In addition, ULF and SPD combined will meet the safety standard of UL 1449, which requires end-products to short circuit in time for safety purposes when abnormal current occurs.


(2) Surface Mount MELF Fuse (SMF)

0204 MELF packaging, SMF is Firstohm's second non-resistor product. Stand-alone, SMF would fuse within short time to protect the circuit from overcurrent. Used in parallel with other surge-resistant components, SMF would delay unexpected surge entering the circuit, thus allowing surge-resistant component in parallel more time in responding and depleting the strength of unwanted surge.


~ end~