sdr1 Posted February 14, 2005 Report Share Posted February 14, 2005 hi. i am working on a project and nee some advice about variable resistors.I have 1 power source.2 light bulbs.and 1 variable resistor.is it possible to wire these in such a way that bulb "A" will stay at a constant brightness, while bulb "B" can be made dimmer using a variable resistor ? thanks,sion. Quote Link to comment Share on other sites More sharing options...
Kevin Weddle Posted February 14, 2005 Report Share Posted February 14, 2005 This is simply a parallel circuit. The trick with the lightbulb is that it requires a certain voltage range to operate within. It will draw current that will drop the voltage because of the resistor. So all you need to do is calculate. If you have the bulb requirements then I will tell you what resistance you are looking for. Quote Link to comment Share on other sites More sharing options...
sdr1 Posted February 14, 2005 Author Report Share Posted February 14, 2005 thanks. im not sure what the bulbs are at moment. but thanks coz i just needed to know if it was possible for now.so, if i connect 1 bulb straight to the power supply, and the other to the power via a v/r then i should be able to lower the brightness of the 1 bulb. thanks again.sion. Quote Link to comment Share on other sites More sharing options...
audioguru Posted February 14, 2005 Report Share Posted February 14, 2005 I am also not sure which bulb you will use.If you use a 100W bulb and turn it down to half-power, the variable resistor will heat with the other half of the power, 50 Watts!You would need 100 regular 1/2W variable resistors, or a huge expensive one.That's why people use inexpensive dimmers that have electronic switching circuits in them. The circuit switches full power to the bulb 120 times per second. When you turn it to bright, the power is switched to the bulb most of the time. When you turn it to dim, the power is still switched at maximum, but the 120 times per second pulses are very narrow, so the power to the bulb is on for hardly any time.Because the circuit switches, it doesn't get hot. One moment it is on, it doesn't heat. The next moment it is off, it doesn't heat.It is called, Pulse-Width-Modulation. Quote Link to comment Share on other sites More sharing options...
prateeksikka Posted February 21, 2005 Report Share Posted February 21, 2005 IS IT ALSO POSSIBLE TO CONTROL BRIGHTNESS OF BOTH BULBS BUT IN A VARIABLE MANNER RATHER THAN CONNECTING ALL 3 IN SERIES?PRATEEK Quote Link to comment Share on other sites More sharing options...
audioguru Posted February 21, 2005 Report Share Posted February 21, 2005 Hi Prateek,Dimmers control the brightness of more than one lightbulb by connecting all the bulbs in parallel. Quote Link to comment Share on other sites More sharing options...
login
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.