Electronic Ballast

       A write up about connecting a ballast to the fluorescent lamps. Comparison on magnetic and electronics ballest for your fluorescent lamp bulb.

Edited by Lim Siong Boon, last dated 22-Aug-2010.

email:    contact->email_siongboon  

website: http://www.siongboon.com

Topic Discussion Overview

  1. Magnetic & Electronic Ballast Compare
  2. Electronic Ballast Testing & Measurement
  3. Electronic Ballast are Common
  4. Electronic Ballast Circuits

1. Magnetic & Electronic Ballast Compare

Finally the old magnetic ballast will be phasing out. The electronic ballast has so many advantages that I see no reason not to use them. On the web, I see that electronic ballast is also known as digital ballast. Electronic ballast and digital ballast means the same thing.

Electronic ballast used to be expensive; something relatively new. Today, we can get them at a very reasonable price. In long run, it is cheaper to use a electronic ballast than a magnetic one.

Electronic ballast contain less metal parts. It is no doubt that raw material such as metal will be getting more and more expensive. It makes much more sense to start using electronic ballast now. Let's get started, and understand the other advantages of the electronic ballast. Learn how to connect up them with your fluorescent lamp.

I have align the old method of using the magnetic ballast on the left column, and the electronic ballast on the right column, so that we can compare side by side.

Circular Flourescent using
Magnetic Ballast and Starter

Circular Flourescent using
Electronic Ballast

(Click image for larger view)

My old fluorescent lamp installation.

Video: MVI_6953.avi (see how the lamp flicker upon switched on, and the flickering after switching on)

(Click image for larger view)

My new installation using the electronic ballast (model: EBCFL-001) from saveOne. The fluorescent lamp and the AC wiring remains the same. Old ballast and starter are removed, and replaced with the electronic ballast. The ballast is very light and is able to plug onto the circular fluorescent lamp easily.

Video: MVI_6954.avi (see how fast and stable the lamp's light is. It is amazing.)

(Click image for larger view)

(Click image for larger view)

Magnetic Ballast Schematic (Click image for larger view)

Electronic Ballast Schematic (Click image for larger view)

The magnetic ballast is simply a inductor core structure, limiting the amount of current to the fluorescent lamp. The video clearly demostrates the starter assisting the fluorescent lamp to start up. A lot of flickering is observed during the initial switched on. Flickering can also be observed during the steady state; after the initial start up. The steady state flickering is mainly contributed from the 50Hz in the 230Vac power supply. My camera is able to detect the 50Hz, hance the flicking.

I managed to have the electronic ballast connect to my fluorescent lamp. Took some video for the comparison between the two type of ballast. The installation was very easy and straight forward as show in the following schematic. The ballast is specially design so that you can plug directly into the circular fluorescent lamp. There are no starter to replace with.

I am excited by the fact that the fluorescent is instantly switched on without any flicker. The lack of flickering means that we can have longer life lamps; the in-rush current is less as compared to the configuration that uses a starter and magnetic ballast. Lamp often gets black smoke layer inside the tube near the terminal's end. I guess it is due to the in-rush sparkling current. I will monitor my lamp life to see how good the electronic ballast performs.

The switching on and off of the fluorescent lamp is known to shorten it's life-span. With electronic ballast, it will make more senses to switch it on and off more often to save our electrical bills with last impact on the lamp.


The instant on and off of the lamp also means that it is suitable to be integrated to PIR sensor or some home automation control system. You will not get the annoying flickering when switching on the light. It will be on at an instant, just like a digital 1 and 0.

I also notice that it generate less noise when user switch on or off the lights. Have you notice that your radio/TV gets noise disturbance, everytime you switch on/off your lights. The electrical noise can propagate across the room through our AC power line. Ever since I have changed to this electronic ballast, I have not encountered any more of this issue. This would be great for those with Hi-Fi audio system at home. You will get less switching noise on your high end sensitive equipment.

As observed from the video, the lamp hardly flicker during its steady state. There is hardly any, captured by my camera. The electronic ballast drives the lamp at a frequency higher than 50Hz. Human eye will not be able to detect the flickering easily. The higher frequency would also be more comfortable to our eye. There are commericial study lamps that helps user reads more comfortably. The electronic ballast is the one that is providing the result.

Some reference on how a fluorescent light can affect human eye




You may think this product is expensive. This electronic ballast from AM NGV (S) Pte Ltd cost only a couple of dollars each. A cost comparable to that of my starter and old magnetic ballast. It will save me quite a significant cost in long run. I can change my lamp less often and there will be no starter to change. Definately worth much more with all the other benefits that it can deliver.

(Click image for larger view)

My old ballast with the starter & it's holder.

The ballast is made of copper coil and steel plate, therefore there is quite some heavy. The setup generate significant heat during operation. The heat causes the surrounding plastic parts to become very brittle after a very long period of use. Therefore you need to be careful when securing the wire. The old plastic might just shuttled into sandy particles; the metal parts covered by the plastic will be exposed. Remember to tape the exposed metal parts.

(Click image for larger view)

click here for product brochure.

saveOne Electronic Ballast (model: EBCFL-001),
from Power Image Pte Ltd.


Address: 63 Hillview Avenue, #08-01, Lam Soon Industrial Building, Singapore 669569.
Tel: +65 6764 3333, Fax: +65 6862 6277

Product is distributed by AM NGV (S) Pte Ltd




Other electronic ballast brand:

The electronic ballast is much more lighter than my old ballast. It is make up of electronics circuit board; driving the fluorescent lamp. The company claims that it is energy saving; having a power factor of 0.95. Unlike the magnetic ballast, electronic ballast would be of a less inductive load nature. The electronic ballast having a better power factor, draws less current. The reduce in current flow also results in higher efficiency and less heat generated.

The product also claims to have brighter luminence. From naked eye, I can hardly see any difference in the lamp brightness. I may get the lux difference if I measure it with a lux meter, but this does not bother me much. This electronic ballast is still a great choice with it's many other benefits.

They also have the electronic version to replace my 2 pin compact flourescent lamp (PL lamp). The 2 pin PL lamp also requires a magnetic ballast connecting in series to it. You may not notice any starter required for your PL lamp; in fact the starter has been built into the PL lamp tube. This means that if your fluorescent or starter is not working, you got to replace your whole PL lamp. Notice how the PL lamp flicker when it is turned on; it is the starter inside the lamp.


NOTE: Please note that a good power factor does not mean a good efficiency in power consumption. Good power factor indicates a higher efficiency in the use of the current (Ampere).
Power factor of 1.0 is the best efficiency, while 0.0 is the worse.

More information about power factor.

Updated as of Date: 19 Dec 2012


- high reliability
- still adopted widely among the population, therefore it is currently cheaper in cost.

- lamp flicker when it get switched on.
- need a starter component.
- lamp and starter need frequent replacement. (more wear and tear)
- heat generated by the magnetic ballast
- might virbate and generate a humming sound.
- generate noise when switching on/off which will disturb other electronics appliances.
- heavy.
- fluorescent cannot be dimmed.

Updated as of Date: 03 Sep 2010

- instant lamp light up. (suitable for smart control interface)
- longer fluorescent lamp life
- no starter required
- easy to install. (plug ballast directly to the fluorescent lamp)
- power saving
- power factor 0.95, which is close to 1.0
- less heat generated from the electronic ballast (lower current).
- does not disturb other electronics appliances
- cheaper maintainance cost
- light weight
- brighter luminence (not yet verified)
- quieter operation (working at higher frequecy)
- dimming feature is possible with a electronic ballast.
- lamp efficiancy increases ; operating at a high frequency.
- reduces light flicker and eye strain ; operating at a high frequency.


- slightly higher cost. (price would get cheaper and cheaper.)
- not as widely or easily available in the shops. (shouldn't be an issue in future.)
- still a rather new thing to the installers.



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2. Electronic Ballast Testing & Measurement

Setup done to measure the lighting intensity (LUX)

I have received a few feedbacks from friends after installing for them this electronics ballast. They mention that the lighting intensity seems lower than their old magnetic ballast. This is very different from the observation that I had; my observation was that both ballast does not have any noticeable difference in brightness. The light intensity that our eye sees is non-linear and is rather subjective. Non-linear means that in order for our eyes to perceive a double in lighting intensity, the actual intensity will have to be much more than a double. This motivates me to do a brightness measurement test, which is also an opportunity to verify the manufacturer's claim of their ballast being able to increase the lamp's brightness. This will also conclude the perception of my friends and myself. The light intensity LUX meter will be our best judge to provide us the answer that I am looking for.

Some interest article on human perception on lights:
- The whole story behind display specifications and human vision.pdf
- Human Visual System.pdf
- Brightness, Color, Contrast & Resolution Criteria for High Quality Digital Imaging.pdf

The meansurement was setup in my kitchen to compare the lighting intensity (LUX), between the electronic and magnetic ballast. It measures about 165 Lux at about 1450mm away from the center of the circular fluorescent lamp. It was tested that about 160 Lux was from the lamp above the meter while the rest of the 5 Lux unit was contributed from the lamps nearby (about 4m away). They were tested by switching the specific lamps on and off.

After completed my measurement for the electronic ballast, I realised that my starter and it's holder was thrown away after replacing it with the electronic ballast. Instead of spending the money to buy a new holder, I decided to do the test while installing the electronic ballast for my friend and grandmother.

Updated as of Date: 01 Oct 2010


I happen to read some article about electronic ballast controlled fluorescent. The fluorescent tube takes some time to warm up and reach it's full brightness. The follow are some article that I found:

- http://www.nscave.com/Reviews/florescent%20overheat.htm
- http://www.bghydro.com/BGH/static/articles/0506_digiballasts.asp
- http://shine.yahoo.com/channel/life/how-to-deal-if-you-break-a-compact-fluorescent-lightbulb-cfl-2395918
- http://ask.metafilter.com/112732/Why-do-specialtyshaped-compact-fluorescent-bulbs-take-longer-to-come-to-full-brightness-than-CFL-bulbs-in-the-more-standard-helical-shape
- http://www.consumerreports.org/cro/magazine-archive/2010/october/home-garden/light-bulbs/how-to-choose/index.htm
- http://www.life-support-technologiesllc.com/CFL.html


Updated as of Date: 17 Apr 2011

Meter reads 160 Lux at a distance of 1450mm.

Measurement results for my grandmother's house

Living Room Setup

Measurement was done at about 85cm below the center of the lamp. The lamp size was diameter 406mm

The magnetic ballast gave off brighter lights 470 lux, with the AC current reading of 0.357A.

After changing to the electronic ballast the illuminance was reduce to 284 lux, with the AC current readin of 0.110A. The lux drops about a third from the magnetic ballast (reduce), but the current was 3 times much more lower.

This means that the current flowing through the cable was much lesser given the amount of illuminance. The same cable is able to carry 3 times more number of lamps. It might translate to lower energy consumed (please read measurement results).

If we compute the illuminance efficiency over the amount of current flow.
Magnetic ballast (lux/amphere) = 470 lux / 0.357A = 1316.53 lux/A
Electronic ballast (lux/amphere) = 284 lux / 0.110A = 2581.82 lux/A

The efficiency is double in the area of current carrying. This is expected, since a magnetic is inductive in nature. For energy efficiency, it would be measured differently. (see the result interpretation on the measured current)

The following section presents the summary of the results and also a detail interpretation.

Updated as of Date: 03 Oct 2010

Dining Area Setup

Measurement was done at about 85cm below the center of the lamp. The lamp size was 299mm.

The magnetic ballast gave a measurement of 309 lux, with the AC current reading of 0.458A. There are burn mark found near the tube's end; it must be quite an old lamp.

The electronic ballast gave a measurement of 197 lux, with the AC current reading of 0.090A. illuminance is also about a third lower while current flow was 5 times lower.

Compute illuminance efficiency over the amount of current flow.
Magnetic ballast (lux/amphere) = 309 lux / 0.458A = 674.67 lux/A
Electronic ballast (lux/amphere) = 197 lux / 0.090A = 2188.89 lux/A

The efficiency is more than 3 times. That was a lot more different than the measurement done for the living room. Perhaps it was the old lamp that cause the difference.

For all the measurement done for the 299mm diameter lamp, the current reading were almost constant at 0.09A. (please check up the following section on the results) The electronic ballast is about the regulate a constant current for all the lamps.

Summary of the measurement results

The following were the lightings intensity (LUX) and current (A) results taken from various rooms during the day time. The first row shows the result from a magnetic ballast and the second row the result after replacing it with an electronic ballast.

The results were rather consistent, telling the same story as mentioned above.

The first column "LUX (Lamp switched off)" is for nulling purposes. The room/environment lighting condition had to be taken as a reference before the actual lighting intensity was taken. The outdoor sunlight is likely to contribute to the reading especially if the measuring meter is place near the window. Light intensity from the sun can change quite quickly, considering the unpredictable cloud movement blocking the sunlight. Another reference is necessary for the electronic ballast installation because the outside intensity might have changed during the change-over period.

The second column "LUX (850mm below the lamp)" is the intensity reading when the lamp is switched on. The reading includes lighting intensity contributed from nearby light sources.

The thrid column "Effective LUX" is the result from the second column minus the first column. This should take away the LUX reading resulted from other light sources; the remaining will be the actual LUX reading from our lamp of interest. The reading various from lamp to lamp. They were closely related to the lamp in use during the experiments. Old lamps has a lower LUX reading. New lamps has a higher LUX. This was verify during the test against new and old lamps in the coming next section.

The last column "Current" indicates the amount of current flowing through the cable. It might not represent the amount of energy consumed. The energy being consumed is represented by the real power, which can be measured by a power meter. I did not had this equipment, and was unable to do the test. Low current readings indicates that a smaller diameter cable can be use to carry the power. This means that you could carry more loads on the same cable, or using a thinner cable to deliver the power to your load; all these can translate to lower cost. Inductive or capacitive load will have imaginary + real power supplied to it. This imaginary power results in the additional AC current flow (charge & discharge the load), hence a thicker cable is required. Loads that indicate a power factor of 1.0 means that they are drawing 100% real power. Anything thing less than 1.0 indicates the imaginary components. The lower the load's power factor, the more the current will be needed to flow through the cable. Hence, a low power factor is an indication of poor efficiency. Our service provider (Power Station) will always  try to balance the load so that a near power factor of 1.0 can be achieve. This will make the best use of the power transmission cable.

Updated as of Date: 03 Oct 2010

Living Room (Lamp size: 406mm)
Ballast Type
LUX (Lamp switched off)
LUX (850mm below lamp) Effective LUX

Dining Area (Lamp size: 299mm)
Ballast Type
LUX (Lamp switched off)
LUX (850mm below lamp) Effective LUX

Room 1 (Lamp size: 299mm)
Ballast Type
LUX (Lamp switched off)
LUX (1800mm below lamp) Effective LUX

Room 2 (Lamp size: 299mm)
Ballast Type
LUX (Lamp switched off)
LUX (850mm below lamp) Effective LUX

Kitchen 1 (Lamp size: 299mm)
Ballast Type
LUX (Lamp switched off)
LUX (850mm below lamp) Effective LUX

Kitchen 2 (Lamp size: 299mm)
Ballast Type
LUX (Lamp switched off)
LUX (850mm below lamp) Effective LUX

Lighting Intensity comparison with old & new lamps

The electronic ballast mounted for the dining area. Old and new lamps were tested for a comparison. The reading was taken during the night time, therefore the nulling LUX value (contributed from other lighting source) remains the same.

The electronic ballast product results in a lower intensity of light. The low illuminance is also closely related to the condition of the lamp. As shown in the results on the right after changing to a new lamp, the current flow remains the same while the brightness was increase by double. It was definately a lamp problem.

To compare the new/old lamp theory even further, I had done another test in Room 2. This time, I am comparing all the measurements against new/old lamps as well as magnetic/electronic ballast.

Magnetic ballast lighting intensity is much higher, at the expenses of higher current flow. The new lamp was not only brighter, but it also results in lower current flow than the old lamp. This was unlike the electronic ballast where the current flow was almost constant irregardless if it was an old or new lamp.

The new lamp that I brought for this test.

Updated as of Date: 03 Oct 2010

Dining Area (Lamp size: 299mm)
Ballast/Lamp Type LUX (Lamp switched off)
LUX (850mm below lamp) Effective LUX
Electronic/ Old lamp 22
Magnetic/ Old lamp 22

The LUX reading after replacing it with the new lamp was even higher than the magnetic ballast fixing that was measured in the day time! The best part was that the current remains the same. Increase in brightness without spending more energy. This shows that the LUX reading is quite closely related to the condition of the lamp.

Room 2 (Lamp size: 299mm)
Ballast/Lamp Type
LUX (Lamp switched off)
LUX (850mm below lamp) Effective LUX
Electronic/ Old lamp
Electronic/ New lamp 1
Magnetic/ Old lamp 1 424
Magnetic/ New lamp 1

From the experiment for Room 2, it shown that new lamps can emit more lights yet using less current.


The results were quite clear and consistent. I had also done the same measurement in my friend's house before doing the setup as shown above. Their feedback was indeed true as shown in this experiment.

Replacing the ballast with the electronic version from saveOne does improve the efficiency, but at the expenses of a slightly lower illuminance. With the well regulated current from the electronic ballast, I will expect the life-span of the lamp to be longer. For new lamps using the saveOne electronic ballast, the lowered illuminance was not noticable; for old lamps the brightness change was noticable. It is recommended to change your lamp to a new one, when switching from magnetic ballast to an electronic ballast.

The experiment still lacks the test on energy efficiency. I will need a portable power meter in order to do this test. I have to do it another time.

Updated as of Date: 03 Oct 2010

Power Measurement

I have managed to got hold of a power meter to do some measurement.

Energy efficiently using
Electronic ballast (lux/watt) = 145 lux / 27.8W = 5.22 lux/W
Magnetic ballast (lux/watt) = 207 lux / 46W = 4.50 lux/W

The efficiency using the saveOne electronic ballast was better than the magnetic ballast but it was not as good as what I had expected. It was about 16% improvement. However, the current was reduce by 52%. The power wattage was reduced by 40%. The reduced in power consumption results in lower Lux but has increase the efficiency of the lightings. The lower current helps to keep the cable size lean, which may results in lower infrastructure cost.

The next experiment I am looking forward would be to test various electronic ballast, to compare their performance.

Updated as of Date: 06 Oct 2010

My Kitchen (Lamp size: 299mm)
Ballast/Lamp Type
LUX (1400mm below lamp) Power Factor
Electronic/ Old lamp
Magnetic/ Old lamp 207

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3. Electronic Ballast are Common

On the right, are some photos of our current fluorescent lamps that we have outside our Singapore HDB flats. This is the fluorescent lamp that was replaced during the Aug 2005 period. If I am not wrong, all the Singapore HDB flats had been changed with this same with electronic ballast lamp fittings. I could still remember it because I was working as a temperory staff with a lighting company. We were assembling these lamps in-house, preparing for the on-site installation. You can also watch the following video. The lightings were not flicking when captured on my camera. If you noticed carefully, there were no starter.

The new installation makes sense because it will significantly reduces HDB maintenence cost and work. Each HDB flat (12 storey) has about 100 lamps, and the whole town of flats. Imagine the kind of maintenence that has to be done. It make sense to install the electronic ballast, which is why commercial buildings/offices are usually installed with the electronics version. The strange thing was that most HDB home were still using the magnetic ballast. Perhaps the lower material cost was the reason behind most home funishing contractor's choice. I am quite bias against the general contractor; there were a number of incident that I had with them in my work. They had the mentality of using cheaper material at the expenses of their customer to gain more profit. Always seek alternative opinons when it comes to engineering solutions.

Althrough this lamp design looks very simple to most of us, it was one of the most efficient lamp design I had seen so far. I was quite sensitive to the reflector design during that time, because lightings design was part of my work in my previous job. I was working on a security imaging equipment.

The lamp itself has no cover, which was something good.  The cover can block a significant amount of light; the attenuation could be as high as 50% or more; even if the cover is clear, see through. I like the reflector design for this HDB lamp. The reflector was one of the most efficient reflector that I ever seen for the fluorescent tube.

The reflector has a sharp bended on the center (which is block by the tube) and formed a curved shape down to both sides. This shape can deflect the backward direction light energy, back to the front. The reflector surface was coated with matt white paint, which is an excellent surface to disperse the lights evenly in all the direction. If you look at the photo with the lights on, you can hardly see the fluorescent tube itself. The reflector has done a good job.

When I first started designing the reflector, I had this myth that a reflector need to be a shining surface; I think most of us will think the same. This was what my company were doing. If you notice the old reflector design, they were made of stainless steel with mirror surface finishing; I could still see it on today's lamp too. This type of reflector will not be able to lit up your room as evenly and as bright as the one with a matt white surface. The result would be a room that seems not bright enough. Unless you want to focus the lighting source to a location, you should use a reflector with matt white surface. Those in the field of interior design/art/photography will understand it better. I actually got to learn about this through the internet. I was very shock and surprised when I first learned about it.

Energy Audit of selected HDB residential blocks in Singapore Aug 2004.pdf

Updated as of Date: 25 Sep 2010

(Click image for larger view)
(Click image for larger view)

Watch the video >> hdb lamp video cliphdb_lamp5.avi




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4. Electronic Ballast Circuits

Investigating 12Vdc operated fluorescent lamp  

I have been learning about fluorescent for quite some time. The fluorescent that I have encountered were operating with 230Vac. Learning about them is difficult and dangerous for me. I saw in the internet that fluorescent can be operated using only a 12Vdc power. The circuit is unbelievable simple. There were still many concepts about fluorescent that I could not understand. This makes me very interested to understand more about 12V operated fluorescent lamp. I prefer playing with low voltage.

Real Star 12Vdc fluorescent bulb



Dated: 2012-04-01

I am at my luck. Managed to see this 12Vdc operated lamp in one of the shop. I tried this lamp using a 12Vdc seal lead acid battery and it works. Yes, this is the lamp I was looking for. The instruction guide behind mention that it will work even if the power polarity is reversed. I am impressed and tried it out. The bulb smoke out. The bulb was burned. Oh dear, I have burned the bulb before I have the chance to open it up for probing. Really regret trying what the user guide said.



It no longer work anymore. I have had powered it up only once. The pictures on the left shows how it looks like inside. Simple circuit. Then I saw components missing. They were the diode bridge. The circuit that enables the reverse polarity feature. No wonder the bulb was burned.

I managed to reverse engineered the circuit, which as follows. Still new to coil and transformer, I am not sure how to work out the transformer used.

This lamp consumed about 0.5A, the reading from my power supply. The circuit uses a transistor D882. The interesting thing to note is that it uses only 2 pin to power up the flourescent. I always thought that 4 pins are required to power up a fluorescent tube. This is not true. What most schematic for 12V operated fluorescent shows is that both pins from one end of the fluorescent tube are shorted together. This is what fascinates me to explore DC operated fluorescent. I learn something new,

Actually I wanted to probe this circuit with my oscilloscope, but it was damaged. The worst part was that, this was the only lamp the shop had. I went to many other shop, but non of them sell 12Vdc fluorescent lamp. There goes my experiement.


12Vdc blue fluorescent lamp (for car lighting)





Dated: 2012-04-17

This was another lamp that I purchase from Mustafa. When I powered it up the lamps works ok, but after about 10sec, I smell smoke. The capacitor pops up. This is bad. I tried to reversed out the schematic. The design uses 4 pins of the fluorescent which is not what I was looking for. So the story is short for this lamp.

Component includes 1N5404, npn transistor D2061.

12Vdc fluorescent lamp (for car lighting)



Dated: 2012-05-18

Thank god, I managed to purchased this dc operated fluorescent lamp that I was looking for. The following is the schematic. The design is what I was looking for. The two pin at one end of the fluorescent tube is treated as a single point.



Power drawn from the power supply is 12V 0.4A.

The npn transistor used is D313.

Let's get started to probe the waveform that lite up the fluorescent lights.

Waveform probe on the 12Vdc fluorescent circuit

Test point 1

Click to enlarge the waveform


This is my setup. My scope can only accept a maximum of 300V. I have to be careful not to damage my scope. My probe allows attenuation. I have set to x10 mode. This will attenuate the signal by a factor of 10 before reaching my scope.

The probe will be place at test point 1, 2, 3, 4, 5, 6 which are clearly indicated on the schematic.

Test point 1 is simple. It is the 12Vdc from my power supply. The ground reference is the power supply gnd.

Test point 2


This is the waveform at the middle of the two short fluorescent tube. Voltage is quite high at 120Vp-p. The frequency of the fluorescent light is flickering at a very fast rate of 80Khz.

The means that the fluorescent is able to light up itself with a voltage of about 120V at a fast frequency of 80Khz.

Test point 3


This is the full waveform found at test point 3. It shows the waveform that is powering up the two fluorescent tube. The voltage is even higher at 288Vp-p. Do not touch those high voltage point as you may get a little shock.


Test point 4

  This is the input to the transistor, which is switching the voltage. The voltage here is quite small at 17.6Vp-p, switching on and off.

Test point 5

  The same switching signal after attenuated by the resistor and capacitor at 11.6Vp-p.

Test point 6


This is the driving power for the primary coil of the transformer. Peak to peak is relatively higher due to the switching effect. The 12Vdc has been switch to generate this waveform 34.4Vp-p.

This input power will go through the step up transformer, resulting in the 288Vp-p output that we have observed earlier. The circuit is simply an inverter circuit, that converts a 12Vdc input to 288Vp-p or 203Vrms at a frquency of 80KHz. The high voltage and frequency is enough to light up a fluorescent lamp.


The tube taken from my first Real Star's compact fluorescent tube was used to replace one of the short tube.

Two different tube connected in series.

Both the compact tube and the short straight tube lights up.


Next the wiring from the compact tube's wiring was unwind.

You can see the 2 pair of wire from both end of the tube.

Only each wire from each end of the tube was connected.

The tube lights up normally. This shows that the fluorescent tube only requires 2 pin in order to light up.


A 40W round fluorescent tube was connected, with the 2 small tube removed. Only 2 pin out of the 4 pins on the round tube were used. The tube was powered up by the full 288Vp-p voltage.

The circuit is able to powered up the 40W tube. The power input to the circuit observed is 12V 0.7A.

There is an increase in current draw from the power supply.

  The same round tube is now connected in series with the short tube. The tube lights up as well. Seems to be a little bit dimmer.

Test point 3

  This is how the waveform looks like at test point 3 when the tube was replace by the 40W fluorescent tube. The voltage is much higher at 448Vp-p 85KHz. My scope has reached its limit, and could not display the full waveform. The change in the fluorescent tube will affect the driving circuit.

The Real Star's compact fluorescent tube was powered up by the saveOne PL lamp's electronic ballast. The electronics ballast requires all the 4 pins of the fluorescent tube. 4 wire or 2 wire from the fluorescent, the tube will light up.


What I have understand from the internet is that the coil on one end of the fluorescent will helps to warm up the gas inside which helps it to start up. With the high frequency electronics drive, it may be unnecessary.

Now I have a better understanding of the fluorescent after doing all these experiments.



DC Voltage input electronic ballast from other website.

(Click image for larger view)

Other related articles:

- 12V operated electronic ballast fluorescent lamp, from website http://www.repairfaq.org/sam/schfil.htm
- How does a fluorescent starter work.pdf
- A simple inverter for flourescent lamps.pdf
- self oscillating dimmable electronic ballast.pdf
- 702PET20, microcontroller simplify lamp ballast design.pdf

- AN1501 Simple Microcontrolled Ballast.pdf
- AN1543 Electronic Lamp Ballast Design.pdf
- electronic fluorescent lamp ballast, st application notes.pdf



- http://www.newworldencyclopedia.org/entry/Fluorescent_lamp
- The ABC of electronic ballast (from Philips), ABC of electronic fluorescent ballast.pdf
- Ballasts for Fluorescent Lamps.pdf, (from NLPIP National Lighting Product Infomation Program)
- http://www.sizes.com/home/fluorescents.htm
- Electronic ballast report, SREB2.pdf
- flicker or humming, http://home.howstuffworks.com/fluorescent-lamp6.htm
- electronic ballast advantages, http://www.eballast.com/ballast_savings.aspx
- Metal Halide Ballasts, http://www.bchydro.com/powersmart/technology_tips/buying_guides/lighting/metal_halide_ballasts.html
- Electronic and Digital Ballasts from HID Hut, http://www.hidhut.com/catalog/digital-ballasts-c-21.html
- Fluorescent Dimming, http://www.etcconnect.com/Community/wikis/products/fluorescent-dimming.aspx
- Compact Fluorescent Lamps, http://www.energysavers.gov/your_home/lighting_daylighting/index.cfm/mytopic=12050
- The Impact of Electronic Ballast on Fluorescent Lamps, http://www.bestproducts.com.hk/en-gb/light/eb/electronic_ballast.htm
- T12-Magnetic to T8-Electronic Ballast/light, http://reviews.ebay.com/T12-Magnetic-to-T8-Electronic-Ballast-light_W0QQugidZ10000000007691483
- T8 Fluorescent Lamps and Electronic Ballasts, http://www.mge.com/business/saving/detail/t8.htm
- Fluorescent Ballasts, http://www.lightsearch.com/resources/lightguides/ballasts.html
- FUTURE BRITE ELECTRONIC BALLASTS vs. MAGNETIC, http://www.planetnatural.com/site/xdpy/kb/future-brite-ballasts.html
- Don’t get your fingers burnt: The truth about electronic ballasts, http://www.maxigrow.com/Resource/Downloads/Dont_get_your_fingers_burnt_The_truth_about_electronic_ballasts.pdf
- These ballasts convert the incoming power to an output frequency in excess of 20 kHz. This increases lamp efficiency. http://www.answers.com/topic/fluorescent-lamp#ixzz1LlxlSTRV


Topic/Questions for further research:
- ballast affects fluorescent lamp brightness
- fluorescent lamp compare to LED lighting power consumption
- electronic ballast produce less heat
- lightings without cover. lightings intensity.

Keyword: electronic ballast, magnetic ballast comparison, energy saving, long lasting fluorescent lamps, starter.