Today the ‘fresh air’ can only be imagining. Because, nowadays due to the big industrial developments, the air becomes so polluted that most of the people have to suffer from lot of diseases. But now because of the magic of this small unit, you may say bye-bye to all of these disorders. Although it has lot of advantages, it is a very simple and inexpensive circuit that the people can use it very easily for several years. Room Air Freshener Circuit works on the principle of ionization, which, helps to remove polluted air
Pure air has positive and negative ions in 1:1 ratio approximately. Air becomes polluted due to the ionic imbalance. Ionic imbalanced air has less negative ions and more positive ions. The idea mainly employs here is to apply a high negative voltage, several KV in fact, to a sharply pointed emitter. The negatively charged air is repelled from the emitter resulting in an ‘ion breeze’ you will feel if you put your hand close to the ionizing point.
About the Circuit :

• In the present design, there is a ladder of resistors and capacitors to step up the voltage up to a few KV. The justification for these cumbersome process appears to be little more than the reduction in size of the ladder capacitors achieved by running the oscillator at a fairly high frequency. The ladder runs directly from the mains.
• The circuit works at 50Hz instead of 50 KHz or so is that 1N4007 rectifiers can be used. Ordinary rectifiers are not too keen to work at high frequencies, the main reason being there painfully slow reverse recovery time, which begins to degrade the circuit performance at frequencies as low as 2 KHz in the case of a 1N4007. Readers may be interested in the results of applying a sine wave of increasing frequency to the circuit.
• The main idea behind this is that the charge is transferred backwards and forwards from one row of capacitors to the other on each main cycle, but always moving further up the chain because of the action of the rectifiers. When all the capacitors are fully charged, there will be a voltage across each of them equal, in theory to the peak-to-peak voltage of the mains.
• In practice, the regulation of this type of circuit is very poor, and the full voltage will never be measured because of leakage, corona discharge, and so on. The tiny ionizing current is quite enough to drop the output voltage to about -4KV, which by a strange coincidence is the ideal output voltage from an air ionizer. Voltages above this level tend to produce ozone rather than ions, whereas voltages much lower will not ionize the air efficiently. Touching the emitter directly is enough to reduce the voltage to almost nothing.

Testing :

• A simple tester can be made from a 10KpF capacitor and a neon bulb. Plug in the circuit, and if all is well, its own neon lamp will glow and a few seconds later you will hear a soft hiss from the emitter. If you hold one lead of the tester and move it towards the tip of the emitter, the neon bulb on the tester will begin to flash when its free lead is about ½” from the emitter, and will flash faster as it is brought closer. The flashing is not very bright, so it won’t show in the direct sunlight.
• If the power on LED D33 light unplugs the unit at once and touch the mains plug to the emitter to remove any residual charge on the capacitors. Check the mains plug to the emitter to remove any residual charge on the capacitors.
• If LED D33 glows, but the emitter does not hiss and the tester’s neon does not flash, remove the emitter wire and try to get a sharper point on it. If there is no sign of activity at the emitter at all, check again for a solder bridge between tracks, one of the diodes back to front, a short circuit in one of the capacitors, or a dry solder joint.

Precautions :
Although the circuit as a whole has a very high output resistance, individual capacitors don’t work, so please take care when you are testing the circuit. The capacitors will retain their charge for some time after the circuit is unplugged, and a painful shock can be received from the back of the PCB if you are careless. The circuit can be discharged by touching the mains plug to the ionizing point for a few seconds, and just to be certain you can run the mains plug down the line of diode connections on the PCB.

Today the ‘fresh air’ can only be imagining. Because, nowadays due to the big industrial developments, the air becomes so polluted that most of the people have to suffer from lot of diseases. But now because of the magic of this small unit, you may say bye-bye to all of these disorders. Although it has lot of advantages, it is a very simple and inexpensive circuit that the people can use it very easily for several years. Room Air Freshener Circuit works on the principle of ionization, which, helps to remove polluted air
Pure air has positive and negative ions in 1:1 ratio approximately. Air becomes polluted due to the ionic imbalance. Ionic imbalanced air has less negative ions and more positive ions. The idea mainly employs here is to apply a high negative voltage, several KV in fact, to a sharply pointed emitter. The negatively charged air is repelled from the emitter resulting in an ‘ion breeze’ you will feel if you put your hand close to the ionizing point.
About the Circuit :

• In the present design, there is a ladder of resistors and capacitors to step up the voltage up to a few KV. The justification for these cumbersome process appears to be little more than the reduction in size of the ladder capacitors achieved by running the oscillator at a fairly high frequency. The ladder runs directly from the mains.
• The circuit works at 50Hz instead of 50 KHz or so is that 1N4007 rectifiers can be used. Ordinary rectifiers are not too keen to work at high frequencies, the main reason being there painfully slow reverse recovery time, which begins to degrade the circuit performance at frequencies as low as 2 KHz in the case of a 1N4007. Readers may be interested in the results of applying a sine wave of increasing frequency to the circuit.
• The main idea behind this is that the charge is transferred backwards and forwards from one row of capacitors to the other on each main cycle, but always moving further up the chain because of the action of the rectifiers. When all the capacitors are fully charged, there will be a voltage across each of them equal, in theory to the peak-to-peak voltage of the mains.
• In practice, the regulation of this type of circuit is very poor, and the full voltage will never be measured because of leakage, corona discharge, and so on. The tiny ionizing current is quite enough to drop the output voltage to about -4KV, which by a strange coincidence is the ideal output voltage from an air ionizer. Voltages above this level tend to produce ozone rather than ions, whereas voltages much lower will not ionize the air efficiently. Touching the emitter directly is enough to reduce the voltage to almost nothing.

Testing :

• A simple tester can be made from a 10KpF capacitor and a neon bulb. Plug in the circuit, and if all is well, its own neon lamp will glow and a few seconds later you will hear a soft hiss from the emitter. If you hold one lead of the tester and move it towards the tip of the emitter, the neon bulb on the tester will begin to flash when its free lead is about ½” from the emitter, and will flash faster as it is brought closer. The flashing is not very bright, so it won’t show in the direct sunlight.
• If the power on LED D33 light unplugs the unit at once and touch the mains plug to the emitter to remove any residual charge on the capacitors. Check the mains plug to the emitter to remove any residual charge on the capacitors.
• If LED D33 glows, but the emitter does not hiss and the tester’s neon does not flash, remove the emitter wire and try to get a sharper point on it. If there is no sign of activity at the emitter at all, check again for a solder bridge between tracks, one of the diodes back to front, a short circuit in one of the capacitors, or a dry solder joint.

Precautions :
Although the circuit as a whole has a very high output resistance, individual capacitors don’t work, so please take care when you are testing the circuit. The capacitors will retain their charge for some time after the circuit is unplugged, and a painful shock can be received from the back of the PCB if you are careless. The circuit can be discharged by touching the mains plug to the ionizing point for a few seconds, and just to be certain you can run the mains plug down the line of diode connections on the PCB.