Dimmers
- Different lamps/luminaires produce light with constant brightness once they are switched on.
- For the following spots, the variation of brightness of the lamps is required.
For (i) Photo studios (ii) Stage (iii) Drama theatres (iv) Decorations (v) Various functions.
- The device for controlling the brightness is a “Dimmer”.
- Dimmer is an electrical and or electronics device. It basically changes the current or voltage which is the cause of varying brightness of luminaries.
Let us study the circuit arrangements and operation of these dimmers.
1. Variable Resistance Type Dimmer
1.1 Resistance Type Dimmer
1.2 Salt Water Dimmer
2. Dimmer Transformer
In this category there are two transformers
In this category there are two transformers
- Auto transformer dimmer
- Two winding transformer dimmer
- The dimming can be obtained by varing the voltage applied to the luminary. The variable voltage can be obtained from transformers which are known as dimmer transformers. These are used in theater lighting.
- Explanation of these two types is given below :
2.1 Autotransformer Dimmer
Circuit Diagram Of Autotransformer Dimmer
Operation of Auto transformer dimmer
- A.C. supply connected to the single winding of a transformer. Varying the knob a variable voltage is obtained from the other side to which lamps L1, L2 , L3 , L4 etc. are connected. The lamps get the variable voltage for changing the brightness of lamps.
Advantages of Auto transformer dimmer
- Simple operation
- Reliable operation
- Equipment cost low (single device)
- No maintenance
- Many lamps can be controlled simultaneously.
Disadvantages of Auto transformer dimmer
- Due to manual operation the electrician is engaged all the while.
Application of Auto transformer dimmer
- Stage lighting
- Drama theaters
- Recreation halls
- Exhibition-to attract visitors.
2.2 Two Winding Transformer Dimmer
3. Electronic Dimmer
3. Electronic Dimmer
3.1 Thyristor operated dimmer
3.2 Triac Operates Dimmer