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Subject: Re: Help with Lighting control
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Date: 09/08/00 at 2:16 PM
Posted by: Eero Heikkinen
In Reply to: Help with Lighting control posted by Dev on 09/05/00 at 6:10 AM:
Well, you _can_ rectify the output of your AC power supply. All you need is a bridge of four diodes rated for the current you are going to use, and this is propably the simplest way of getting your lamps under control.
The reason for DC power suplies being so expensive is that they are really deacently build, offering accurate and well stabilized output voltage and over current limiting. Rectifying the AC power supply wont give you clean DC, but it's good enought for driving lamps. For the controlling circuit you have to make better supply voltage; put in at least a capacitor and perhaps a regulator like 7805 etc.
If you want to control the lamp current gradually (not just on - off) you may find better to use PWM rather than linear current regulation, to avoid power losses and heat. You can use the 555 for PWM - see data sheet / application notes.
Hope these few lines give you some help.
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