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The Grainger catalog shows very expensive ways to do this. If you can work with the ballast secondary windings it might be easier but this would still involve reducing the current of a current source. Flourescents running on DC are also probably easier.
I dont advise running a fluorescent lamp on pure DC because it causes
the bulb to blacken quickly on one end. A better way is to use a pulsing
source though a capacitor of suitable size.
Sorry i dont have a schematic handy.
actually I want to use only AC power, and I want to control this dimmer using a remote control. Please suggest on this, and thanks very much for suggesting Grainger. i found one. but they are too costly. Let me see if I can get anythhing in local market
It occurs to me that to control the output of a current source you need a (remote-controlled) variable shunt resistor across it, with the resistor being "off" during startup.
I don't know how well the ballast will tolerate current draws above or below design values. You may need some sort of an L network or a T network that attenuates current to the tube but so the ballast sees a constant current load but presents another current source of lesser value to the tube.
You need the dual of a network that does this with voltages, in the sense that a current source is the dual of a voltage source.
Good problem!!!
I'd start by searching online patents to get some idea of the complexity you'll be looking at.
The most efficient way to dim a fluorescent lamp is using RF. Throw away the ballast and forget about heating filaments.
Connect an RF-generator (powerful enough) to both filaments and you're able to dim from slight glow to full brightness without flickering.
If you happen to have a radio ham nearby he can demonstrate that using his transmitter. Hold the lamp close to the transmitter antenna, put the hand on one filament heater terminal, and the lamp will be lit when he transmits.
Hi!
You can do it by single phase inverter circuit, use IR2109 mosfet driver IC which works upto 600v and it control the output voltage with PWM input signal.By varying the PWM duty cycle you can change the output (AC voltage) produced by the inverter circuit.
I dont advise running a fluorescent lamp on pure DC because it causes
the bulb to blacken quickly on one end. A better way is to use a pulsing
source though a capacitor of suitable size.
Sorry i dont have a schematic handy.
A simpler solution is to build a squarewave inverter using an h-bridge. It doesn't have to be fast or high frequency as long as the dead time is short enough.
Here's an example of a circuit which I designed awhile ago.
I don't know how well it works but someone on another forum built it and it worked.
The incandescent bulb might need increasing up to 40W depending on the dimmer's minimum wattage rating.
I am not sure who told you that or where you got that information,
but the blackening is caused by migration of the metal on one end
of the tube which is caused by a relatively constant dc current flow
or even an average dc current flow. This can only be remedied by
using an ac waveform to drive the bulb and this is the way most
commercial lamps of any significant quality are made.
What helps is to insert a capacitor with the correct rating in series
with the tube, provided of course the drive circuit can work that way.
This guarantees ac operation for the tube.
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