Fluorescent Circuits

A number of people have been unable to find the transformer needed for the Black Light project, so I looked around to see if I could find a fluorescent lamp driver that does not require any special components. I finally found one in Electronics Now. Here it is. It uses a normal 120 to 6V stepdown transformer in reverse to step 12V to about 350V to drive a lamp without the need to warm the filaments.

If you are tired of replacing small night light lamps, try this circuit. The line powered circuit uses a long life cold cathode fluorescent lamp. A simple charge pump technique runs the lamp without any transformer.

The circuit was designed to experiment with using small fluorescent lamps as a broad pattern source of modulated light. The circuit hits the small lamp with narrow 1us pulses at a rate of 10KHz. Each pulse launches about 10 watts of visible light. The lamp starting method is a bit crude but the circuit does work.

The IRPLLNR2 is a high efficiency, high power factor, fixed output electronic ballast designed for driving rapid start fluorescent lamp types. The design contains an EMI filter, active power factor correction and a ballast control circuit using the IR21571. This demo board is intended to ease the evaluation of the IR21571 Ballast Control IC, demonstrate PCB layout techniques and serve as an aid in the development of production ballast’s using the International Rectifier IR21571.

The circuit is built around the IR2520D Ballast Control IC. The IR2520D provides adjustable preheat time, adjustable run frequency to set the lamp power, high starting frequency for soft start and to avoid lamp flash, fault protection for open filament condition and failure to strike, low AC line protection and auto-restart after line brownout conditions. The IR2520D is a low-cost solution with only 8 pins and allows the component count for the complete solution to be reduced down to 19 components.

Vacuum fluorescent displays, known as VFDs(because both vaccuum and fluoroscent are hard to spell) are commonly used in VCRs and microwaves. They are relatively bright and have a low power consumption. Some older calculators used them before LCDs became popular. Having obtained a few Futaba VFDs from a surplus dealer, I went about trying to interface it to a PIC. A plea went out on the PIC list and was soon answered by Kalle Pihlajasaari with a few details on VFDs.

Zetec Semiconductors Applications Notes An overview of the principles behind typical emergency lighting systems, fluorescent tube behaviour, and the requirements of the transistors for efficient voltage inversion. The note also includes two "Royer" based designs for low voltage systems.

Figure 1 presents a block diagram of a typical emergency lighting system. The control circuit monitors the mains supply, and if all is well, allows the charger to trickle charge the battery pack. In the event of the mains voltage failing, the controller then enables the inverter which provides sufficient power to a fluorescent tube to provide illumination.

This application note describes a high performance low cost ballast design using the ML4831 electronic ballast controller IC. The design can be evaluated by assembling the parts listed in this document.

This Application Brief exists as a supplement to Application Note 63. When used with Application Note 63, this document contains all the necessary information to convert an ML4833 Evaluation Board into a low-cost, non-dimming 220V ballast.

Vacuum Fluorescent (VF) displays are becoming more and more common in a variety of applications. Manufacturers of everything from Automobiles to Video Recorders have taken advantage of these easy to read displays. VF displays are available in a wide variety of configurations; clock displays, calculator displays, multi-segment, and dot matrix displays are readily available at a low cost. This application note develops and covers in some detail a small CMOS system consisting of a single chip microcontroller and two display drivers which control a 20 character, 5 x 7 dot matrix VF display.

This reference design is a high efficiency, high power factor and digital dimming electronic ballast designed to drive rapid start fluorescent lamp types. The design contains an active power factor correction circuit for universal voltage input as well as a ballast control circuit using the IR2159. The design also includes a PIC16F628 microcontroller and an isolation circuit for connecting to a Digitally Addressable Lighting Interface (DALI). Other features include EMI filtering, transient protection and lamp FAULT protection.

This circuit is a simple ultraviolate light that can be powered by a 6 volt battery or power supply (such as the power supply on the "Circuits" page) that is capable of supplying 1 or more amps.

Virtually all domestic and professional dimming systems are based on triacs. These devices will conduct once they have been fired, only while current flows in excess of the holding current of the device. These dimmers work very well with a resistive load such as an ordinary Tungsten filament light bulb as the triac can be fired at any point during the mains half-cycle and will continue to conduct until very close to the end of the half-cycle as current is drawn continuously over this period. In this way the lamp current can be adjusted from maximum to zero.

A complete digital dimming system includes the dimming ballasts and a digital control unit for converting information from an Ethernet connection to the communication protocol required by the micro-controller in each ballast (Figure 1). Applications for this system include building management or studio lighting where it is desired to control single or groups of lamps for conserving energy, performing lamp maintenance or creating precision lighting effects.

A zero-voltage-switching (ZVS) controller usually integrates a one-shot circuit, embodied in a VCO system. An error amplifier monitors the output voltage and adjusts the VCO's off-time to keep the output value at a constant level. Each on-time period commences as soon as the primary voltage drops to zero, thus eliminating on/off commutation losses associated with the switching element. The controller also incorporates other convenient features, such as MOSFET drivers, a voltage reference, and overvoltage and undervoltage lockouts. In low-cost circuits, such a complex architecture can lead to a prohibitive cost, especially if you don't need the cited features (in open-loop systems, for instance). Figure 1 shows an 8W, ZVS fluorescent-lamp converter made from two low-cost ICs, a CD4538 and an LM393.

In this circuit the switches are power MOSFETs driven to conduct alternately by windings on a current transformer. The primary of this transformer is driven by the current in the lamp circuit and operates at the resonant frequency of L-C. Unfortunately, the circuit is not self starting and must be pulsed by the DIAC connected to the gate of the lower MOSFET.

The IRPLLNR1 is a high efficiency, high power factor, non-dimmable electronic ballast designed for linear fluorescent lamp types. The design contains an active power factor correction circuit for universal voltage input and a ballast control circuit using the IR2153 for controlling the lamp. Other features include EMI filtering, transient protection and lamp fault protection.

The IRPLCFL5E reference design is an electronic ballast for driving 26W compact fluorescent lamps from 220VAC. The circuit provides all of the necessary functions for preheat, ignition and onstate operation of the lamp and also includes the EMI filter and the rectification stage. The circuit is built around the IR2520D Ballast Control IC.

This reference design is a high efficiency, high power factor, digital dimming electronic ballast designed to drive rapid start fluorescent lamp types. The design contains an active power factor correction circuit for universal voltage input as well as a ballast control circuit using the IR21592. The design also includes a PIC16F628 microcontroller and an isolation circuit for connecting to a Digitally Addressable Lighting Interface (DALI). Other features include EMI filtering, transient protection and lamp fault protection.