I'm applying 1-12vdc to 12 light bulbs. Need them to light in sequence as the voltage increases.?

Question

Please tell me how to wire the bulbs together, the voltage ratings of the bulbs and the values of any componants (resistors?) needed between each bulb to allow them to light in sequence as the DC voltage increases from 1 to 12 volts. I would be extremely appreciative of this information on a home project of my own. Thank you in advance for your considerations. Monty

Answer 1

use voltage dividers with a transistorized switch. this method lights a number of lights matching the input voltage in this case, all the way up the tree to it, rather than just one, so note that. (7V in gives 7 lamps on).

the first transistor comes on if the base reaches .7V (2N2222 or so will work). the next transistor is attached to the base of the first transistor through a voltage divider, the third .... From the collector stick in a 1V Zener for regulation (make sure you get one that withstands 12v in), and the lights then go from there straight to ground (include a resistor here to limit current, try 15 ohms to start, experiment!).

decide how many lights you want, divide your final voltage by that number, and that is the voltage per step (here, 1V). the voltage divider then comes from the voltage per step versus the transistor base ON voltage, across a good sized resistor (say 470 ohms or 1k, whatever you want (watch the current and the power drain here). in your case, if you use a 470 load resistor on the voltage divider, then the second leg of the divider is (470 / (1V/1V-.7V)) = 141 is about a 130 (less is more on the base!).

recap:

so the voltage divider goes from the input into the 130, into both the base and the 470, the 470 goes to ground. the emitter can tie to the input voltage, the collector goes to a 1V Zener, to a 1V lamp, a small resistor, and ground.

the other stages stack right onto this. the input still goes to the 130, then to the base and the 470, the 470 ties to the base of the previous stage. the emitter again goes to the input voltage, and the collector goes to a 1V Zener, a 1V lamp, and a small resistor to ground. sorry, i can't attach a picture here.

Answer 2

You will need a non-linear device, such as transistors or zener diodes to get the light bulbs to light in series. If you use linear devices like resistors then all of them will glow, but some will glow brighter than others.

The easiest and most precise way to do this would be to use 12 comparators and a resistor ladder to compare the input voltage against. Use a comparator such as a LM324. These come in quad packs so you will only need 3 of them and they are cheap. Instead of light bulbs use LEDs and you will be able to drive them directly with the comparator.

Answer 3

To do this right, you are going to need some additional components, and Zener diodes would be one way of doing it. Get a dozen Zener diodes of progressively increasing breakdown voltage, hook each in series with a light bulb, and hook all of these assemblies together in parallel. It will act as you decribed.

Answer 4

If you connect all 12 bulbs in series, and assuming each has the same resistance of the filament, then you would need 144 volts for each individual bulb to drop 12 volts across it. In this configuration if one bulb should burn out they all go out. Now if you connect them in parallel then you will need 12 volts. In either wiring scheme your power supply must supply the necessary current for the bulbs to light.

Answer 5

just use 12 zener diodes, with appropriate B/D votlatges, hooked up in parallel with the source,,, but u will need resistors in dropping order, the closest one with higher value, between diode and bulb, and farthest one with lowest value - to save ur bulbs from burning out from higher current...

Answer 6

basically one, if the information ability that the mild bulb needs to get replaced. Or None, the mild bulb needs to realize the point end that it needs to alter on its very own.