Thread: dome light dimmer (with delay)

pat o change your incadensants out for leds and then use the circuit as is that would probably work

my van has 3 floors and 2 overheads i might do that

BTW MSpaint!!!! DAYUMMMMMM that was a few hrs worth of work

LED's... Hadn't thought of that. Thanks!
MS Paint? Are you on drugs?

MS Paint! Are you Monk? Good job though.

Originally Posted by kronos

just one bulb which is 15W or so. for your 4 you may need a heatsink. a pretty big one

You could also change the 2n3055 from a TO220 package to a TO3 package. It can handle larger currents without a heat sink. Better yet, the 3055 has a large on resistance, a FET would be able to handle a much bigger load without heating up because of the much lower on resistance.

Originally Posted by PatO

MS Paint? Are you on drugs?

I don't do drugs, but since you're such a nice and courteous guy why don't you redesign the scheme in a more evolved graphics package instead of throwing offensive remarks. This kinda behaviour will make me think at least twice before I will share any of my other projects. As they say no good deed goes unpunished.
FWIW I already had the main components in a png so it was a simple matter of copy & paste and some rearranging so no big deal.

Originally Posted by widower

You could also change the 2n3055 from a TO220 package to a TO3 package. It can handle larger currents without a heat sink. Better yet, the 3055 has a large on resistance, a FET would be able to handle a much bigger load without heating up because of the much lower on resistance.

the 2N3055 IS a TO3 package, the MJE3055 which I used is a TO220. of course the 2N3055 is way better, but I was a little constrained on space: it had to go in the lamp assembly which is kinda tight and the TO3 package is almost as big as the whole circuit so for me the MJE3055 was the choice. anyway, to each his own... so if you have the space go for the 2N3055 by all means.

my roomate at school and i are attempting to build this and have hit some issues. Im not a EE but he is, so he understands the electrical diagrams, he says there are a couple components that dont appear on the diagram, the resistor to the left of the pot, and the beige component in front of it. we built the circuit to spec based on the diagram as far as we could tell on a protoboard and hooked it up to a 12v supply and everything but couldnt get it to work. any troubleshooting suggestions?

Originally Posted by kronos

I don't do drugs, but since you're such a nice and courteous guy why don't you redesign the scheme in a more evolved graphics package instead of throwing offensive remarks. This kinda behaviour will make me think at least twice before I will share any of my other projects. As they say no good deed goes unpunished.
FWIW I already had the main components in a png so it was a simple matter of copy & paste and some rearranging so no big deal.



the 2N3055 IS a TO3 package, the MJE3055 which I used is a TO220. of course the 2N3055 is way better, but I was a little constrained on space: it had to go in the lamp assembly which is kinda tight and the TO3 package is almost as big as the whole circuit so for me the MJE3055 was the choice. anyway, to each his own... so if you have the space go for the 2N3055 by all means.

I'm sorry if that remark was taken negatively. I meant it in a sarcastic tone to indicate that I admire your dedication to creating accurate and descriptive diagrams. Please don't think that I am bashing you in any way, shape, or form! I truly appreciate this diagram and will implement it as soon as time permits!

Originally Posted by ethlar

my roomate at school and i are attempting to build this and have hit some issues. Im not a EE but he is, so he understands the electrical diagrams, he says there are a couple components that dont appear on the diagram, the resistor to the left of the pot, and the beige component in front of it. we built the circuit to spec based on the diagram as far as we could tell on a protoboard and hooked it up to a 12v supply and everything but couldnt get it to work. any troubleshooting suggestions?

I have added two small resistors; 470ohm in series with SR1 and 1k2 in series with SR2 in order to have a small impedance when the pot's is zero so as the capacitors discharge or charge through some impedance instead of straight through wire (they're limiting the current a bit); they are not critical and as long as you don't set the pots to zero you don't have to worry. Indeed I added them after the scheme was done and I forgot to draw them in... my bad, but it should work without them given that they are a kind of... let's say added protection. check your connections on the protoboard, because my prototype was done without the small resistors as well and it worked from the moment I powered it up. what exactly is not working? does the led light when you power up the circuit? also take a multimeter and check voltage at:
pin 3: it should be aprox half the voltage of the source
pin 2: after power up it should raise from zero to aprox the voltage of pin 3 in somewhat less than the time constant for the SR1-C1 (time constant[seconds] = R [ohms] x C [farads])
tell me more details cause I'm troubleshooting blind here.
... ok, edited the first post with the updated scheme (the two resistors added)

Originally Posted by PatO

I'm sorry if that remark was taken negatively...

ok, no offense taken. I was tired and just had one of those days and everything upset me.

thanks for the update. we were able to get the led to light but couldnt get the dome light, which i had removed from the car, to light up. we will get back into the electronics lab and check the voltages you listed. i will try to get more details after we get back in.