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  1. Fluorescence

    Boost converter transfer function

    Hello, I have designed a boost converter with the following specification Vin = 24V Vout = 40V Output power = 10W Switching frequency = 100KHz Continuous conduction mode Output caps = 400uF Output caps ESR = 0.33R Boost inductor = 1mH Ripple current = 10% PWM controller = LT1241 Current mode...
  2. Fluorescence

    Non compensated SMPS works fine

    Hello, A circuit that doesn’t work is not nice, but a circuit that does work when it shouldn’t is even worse!………. I am designing mains LED lighting and am using UC3842 PWM controller since it costs just 20 Cents. (Specific LED drivers are too expensive) I have designed two similar current...
  3. Fluorescence

    Minimum voltage level required or Powering CFL's

    Hello, I am writing concerning powering CFLs (Compact Fluorescent Lamps) from the mains. The following App Note from IRF.com shows a fluorescent lamp being powered from the UK mains (240V) .... ...but uses a "valley filler" passive power factor corrector, so the DC bus actually varies from...
  4. Fluorescence

    SMPS stability

    hello, With these fora having recently debunked myths concerning 1. Power factor correction and efficiency 2. Right half plane zero of boost converter ...i wonder if the situation concerning ensuring the stability of a switcher power supply using time domain (step response) methods only is...
  5. Fluorescence

    Feedback compensation on flyback PFC

    Hello, I write concerning a flyback PFC stage with L6561. I refer to Figure 16, page 18 of the following app note... http://www.st.com/stonline/products/literature/an/5956.pdf There are feedback compensation components on both primary and secondary sides. Is this unusual? I would have...
  6. Fluorescence

    RMS current in "Valley-Filler" capacitors of SMPS

    Hello, I am writing with regard to the RMS capacitor current in the “valley filler” capacitors in an 8W off-line 1 transistor forward converter SMPS. I cannot understand why the LT Spice simulator has calculated this charging current so low. Here is the circuit…… *** FIGURE 1 The “valley...
  7. Fluorescence

    Power rating of LED bulb

    Hello, I recently purchased a 1 Watt Mains LED light bulb (240V, 50Hz) Using a 220R resistor in series with the live (hot) line i looked at the current entering the bulb using the scope. The bulb is said to be 1 Watt but i calculated that the RMS of the input current waveform was 8.75mA...
  8. Fluorescence

    Input cap ripple current calculation

    Hello, I just took apart a 15W CFL (240V 50Hz) and did a test on the DC bus just after the diode bridge. (This CFL has a mini , 2 transistor SMPS inside it to power the bulb) The Capacitor just after the diode bridge has 110V of (100Hz) ripple on it (it goes from 220V to 330V) I am trying to...
  9. Fluorescence

    Ripple current rating of SMPS input electrolytic caps.

    Hello, I am trying to work out the RMS ripple current in the DC Electrolytic Caps that occur just after the diode bridge rectifier in my 10W offline SMPS. I apologise for the lengthiness of this post. It is a one transistor forward converter (Mains is 240V, 50Hz). Here is the representation...
  10. Fluorescence

    Electronic design

    Hello, I have designed an electronics product and need to find an investor to take it to market. I don't have finance so am willing to donate the product IP to the investor, in return i would be willing to work for them and finalise the design, get EMC tests done etc. Do you know of anybody...
  11. Fluorescence

    Light bulbs - CFL versus LED

    Hi, I am thinking about how to do a light bulb (~10W) with LEDs..... http://www.lightbulbs-direct.com/product/1007/gls-40w-bc-pearl/ Being offline, the SMPS would need to go in the base, where it would be unventilated and very hot since its above the bulb itself. The heat is thus the biggest...
  12. Fluorescence

    Fluorescent Lights automatically turn off/on

    hello, I recently went to the conveniences in Tesco, Aldershot , UK... and the lights were out when i walked in but came on automatically as i entered. The lights were many small fluorescent tubes. since this is a busy shop...these lights will be OFF and ON'ing all day long.. do you think...
  13. Fluorescence

    CFL versus LED lights

    hello, I am seeking advice on Compact Fluorescent Lamps. They are selling them for 8p each in places in UK now...as they say they are answer to energy saving over incandescent. However, June 08 "Electronics world" says each CFL contains 4g of Mercury.......and in EU alone this equates to...
  14. Fluorescence

    Power factor of mains diode bridge

    Hello, I just bought an 8p Compact Fluorescent Bulb (11W) from Tesco, UK. http://en.wikipedia.org/wiki/Compact_fluorescent_lamp They are supposed to be excellent at being much more efficient than the usual incandescent bulb. I sawed the base out to see what kind of ballast it was using...
  15. Fluorescence

    Which fluorescent lamps are dimmable

    Hello, I am having trouble finding a datasheet for my General Electric, 18 Watt, Biax, 4 pin, compact fluorescent bulb (F18BX/827). I can find various details but none so detailed as would be required for designing a high frequency dimming ballast for the lamp.....eg i need ignition current...
  16. Fluorescence

    Powering Fluorescent Ballast IC

    Hello All, I am making a dimmable fluorescent ballast for fluorescent light using IR21593 Fluorescent driver IC......(datasheet) http://www.irf.com/product-info/datasheets/data/ir21592.pdf Pagfe 11 of this application note shows a full circuit set-up involving the IR21593...

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