Help Needed... Light dimmer

Hey guys,

You're gonna have to be more specific ...
JB

Sorry...

Hey guys,

I want to simulate the sunset and sunrise in my aquarium tank using 2 60 Watts incandescents lights... In order to do that I need help with the circuit design.

I have a Koyo 05 PLC, which can control the start and stop the process. In the morning when the PLC closes a contact, the circuit start to increase the brightness in the bulbs progressively, this last aprox. 10 minutes... In the evening, the PLC will open the same contact and the bulbs goes progressively off...

I know that a SCR or TRIAC will do the job, but I have no idea how increase or decrease the voltage going to the gate...

Would you guys PLEASE help me with this design ???

Thanks in advice,

Seranko

1) SCRs and Triacs aren't controlled linearly by a variable gate voltage.
2) AC lamp dimmers don't use a transistor in series with the lamp as a linear variable power resistor.

Go to www.google.com and search Triac and Lamp Dimmer and you will see how they operate.

One of my friends has written an article about using triacs to dim lights He uses them to control halogen lights but I'm sure you could easily modify his design for what you want. Dimming is controlled by a variable resistor at the moment so you would need to modify it a bit to get it doing exactly what you wanted. You can find it **broken link removed**

Hope this is some help to you.

Here is an old cct...