Problem: I have built a wooden model of a lighthouse. I want to make the light in the house flash. I am can use a soldering iron. I have no circuit experience.

Question: How can I build a simple circuit with the following requirements?

  • 9 V battery (or AA, just not C or D size)
  • bulb could be anything like a Christmas tree light bulb or bigger.

The resulting circuit and battery will fit into a 2" x 2" box that the light will screw into.

It has been suggested to use LED flashers, but how can I control the speed of the flash?

This looks like the right speed to me:

enter image description here

  • \$\begingroup\$ You should be able to easily find LED flasher circuits with a simple search. Looks like about 1/2 Hz to me. You can get them with a kind of "sine wave drive" where the LED gradually grows in strength and then diminishes or else just harshly pulses ON and OFF. I also think blinking LEDs can be bought with the blinking circuit already built into them. Have you done any searching at all? \$\endgroup\$ – jonk Nov 21 '17 at 21:13
  • \$\begingroup\$ Yes, you can buy "flashing" LEDs for this purpose that require no additional circuitry. \$\endgroup\$ – pjc50 Nov 21 '17 at 21:23
  • \$\begingroup\$ Technically this question is not off topic, they are asking for a circuit. \$\endgroup\$ – Voltage Spike Nov 22 '17 at 16:25

Look for something like http://www.ebay.co.uk/itm/3mm-FLASHING-WHITE-Ultra-Bright-3mm-LEDs-pk-of-5-/360320012646. You can run it directly off a 9V battery if you add a 285Ω resistor. Just get the resistor value closest to and higher than my value as they come in all sorts of values depending on what range you can buy. You'll want a little 9V battery clip too to connect on the wires as soldering to a 9V is sometimes hard, and it makes it easy to change the battery.

This is absolutely the simplest arrangement. If you can't get a flashing LED then you're looking at soldering up a more complex circuit that probably isn't worth the effort unless you're into electronics and stuff...

PS. Do you want a switch too?

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  • \$\begingroup\$ Shirley this must be a duplicate, but on the off chance that it's not... \$\endgroup\$ – Paul Uszak Nov 21 '17 at 22:42
  • \$\begingroup\$ ... and don't call me Shirley, Over. \$\endgroup\$ – Transistor Nov 21 '17 at 22:47
  • \$\begingroup\$ @Paul Uszak Thank you. Looks like this will solve the problem. I have switch already mounted and a package of 9v clips. Guess I thought this would be more complex than you have demonstrated. \$\endgroup\$ – Marinaio Nov 22 '17 at 15:43

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