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Libby chen
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Shenzhen FIER Lighting Co., Ltd.
Tel: 0755-27252871, 27252872, 27252873
Fax: 0755-27252872
Code: 518125
Sales Manager: Fiona Chu (朱鹰翘)
Taojiang FIER Lighting Co., Ltd.
Sales Manager: Jojo Long

Simplest 100 Watt LED Bulb Circuit

The article discusses a very simple 100 watt LED bulb circuit using a few high voltage capacitors. The entire circuit could be built at a cost less than $25.

I have already discussed many capacitive type of transformerless power supply circuits in this blog, however all these suffers from a couple of issues, namely lack of optimal current output, and surge inrush vulnerability.

Upon studying capacitive power supplies deeply I could conclude a few crucial things regarding these configurations:

Capacitive power supplies are quite like solar panels which work efficiently, at their maximum power point specs when they are operated with their open circuit voltages, otherwise the current specs from these units go through heavy losses and produce highly inefficient results.

In simple words if we one desires to acquire high current outputs from a capacitive power supplies at will, the circuit will need to be operated with a load having a voltage requirement equal to the maximum output of the system.

For example with a 220V input, a capacitive power supply after rectification would produce an output of around 310V DC, so any load assigned with a 310V rating could be operated with full efficiency and at any required current level depending upon the requirement of the load.

If the above condition is satisfied, it also tackles the current inrush issue, since the load is specified at 310V, an inrush of full input voltage now has no effect on the load and the load remains safe even during sudden switch ON of the circuit.

In the proposed 100 watt LED bulb circuit we employ the same technique as discussed in the above sections.

As discussed, if the input is 220V the load would need to be rated at 310V.

With 1 watt 350mA standard LEDs this would mean adding 310/3.3 = 93 LEDs in series, that’s close to 100nos.

A single 1uF/400V capacitor produces around 60mA current at the above specified 310V DC, therefore for achieving the required 350mA more such capacitors will need to be added in parallel, to be precise a total of 350/60 = 5 capacitors, that could also be a single 5uF/400V but should be a non-polar type.

An NTC thermistor may be added for extra safety, although it may not be critically required.

Similarly a resistor could be also included to provide extra bit of safety from fluctuating voltage conditions.

The resistance value may be approximately calculated as R = Us – VFd/I = 310-306/.35 = 10 ohm, 1 watt

For a 120V input, the above specs would simply need to be halved, that is use 47nos of LEDs instead of 93, and for the capacitor a 5uF/200V would be enough.

Portable Density Meter: DMA 35

The DMA 35 portable density meter measures the density and concentration of your sample and is characterized by the highest level of user friendliness. Its robust and lightweight design enables on-site operation in a wide range of work environments. The four product versions – DMA 35, DMA 35 Tag&Log, DMA 35 Ex and DMA 35 Ex Petrol – differ from each other in terms of interfaces, housing material and intrinsic safety. Each instrument version is tailored to the needs of certain fields of applications.

জাতীয় পরিচয় নিবন্ধন
জাতীয় পরিচয় নিবন্ধন [ আপনি যদি জাতীয় পরিচয় নিবন্ধন করে থাকেন, জাতীয় পরিচয়পত্র সংক্রান্ত অনলাইন সেবাসমূহ পেতে নিচে রেজিষ্ট্রেশন করুন। যদি এখনও নিবন্ধন না করে থাকেন তবে  এখানে ক্লিক  করে অনলাইনে…



Department of Inspection for Factories and Establishments

Ministry of Labour and Employment

Government of the People’s Republic of Bangladesh



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