What is the easiest way to make a 40W incandescent light bulb flash on and off at regular intervals?

Question

I would prefer to use batteries as a power source.

Answer 1

There are several products available to flash lights. Some specialized replacement ligh switches have a flasher function, these are intended to flash a driveway lamp post to aid locating a home

Below is a link for a button which is placed into a light socket which will flash the bulb.

Flashers are also used frequently for the deaf to signal door bells and ringing phones. Check out this type of equipment as it may help you .


You can use X-10 remote modules connected to lights across the home and use an X-10 Alarm interface in mode 2 to flash these lights...

Answer 2

You might have already noticed that the measured resistance of your light bulbs is a lot lower than the 144 ohms expected from the voltage and wattage rating. I was puzzled at first when I discovered the same thing many years ago. The answer to this paradox is that the resistance of the light bulbs at low voltage has been accurately measured but as the filament heats up, its resistance increases, in this case by a factor of about 16 between room and operating temperature of about 3,000 deg K. When you first turn on the light, it does indeed draw a large surge of current that quickly decreases to the operating current after a fraction of a second. This is why switches sometimes have a separate, lower current rating for operating incandescent lights. The answer to your problem is therefore this: a) at nominal rated voltage, your bulb will consume the nominal rated power; the resistance measurements of the filament at room temperature don't apply. The RMS current can therefore be computed from the equation I = P / V, for a current of 0.83 amps. b) At 12.0 volts, the filament will dissipate enough power to heat up significantly and raise the resistance noticeably but nothing like the factor of 16 that occurs at full operating voltage. The current will therefore be less than 12.0 V / 8.9 Ω or 1.35 amps but a lot more than the 0.083 amps you would expect if the light offered the same resistance it did at full working voltage. My seat-of-the-pants estimate would be a current draw in the range 0.2-0.4 amps based on my somewhat limited experience with incandescents. Do try this at home.

Answer 3

Light Bulb Flash

Answer 4

Here is a circuit that uses 4 lamps, but you can modify it for just one lamp (the first one, only -- just don't connect the other parts of the circuit for the other 3 lamps).
http://ourworld.compuserve.com/homepages/Bill_Bowden/page7.htm#aclamps.gif

If the page doesn't come up on the right part, just scroll down until you hit, "120VAC Lamp Chaser".

As for battery power, 40 Watts is an awful lot for batteries. It is too much for alkaline D-cells, and even for small automobile batteries. You wouldn't get much useful life lighting a 40 Watt bulb. I suggest using the AC mains like the circiut does. To generate the necessary 9 Volts a battery would work OK for quite a long time.

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Answer 5

Hire somebody to stand there and flip the switch on and off.

Doug

Answer 6

First, flip the on/off switch to on, then off, then on, then off, etc.

Answer 7

flip the switch up and down over and over.

Answer 8

Doug, you and Steve should start your own electrical engineering firm. You guys are a "gold mine" of knowledge! Thanks!