Electronic Circuits and electronic circuits, electronic schematics plus an extensive resource for hobbyists, inventors and engineers

DiscoverCircuits.com, has 40,000+ electronic circuits, cross-referenced
into 500+ categories.    We have searched the web to help you find quick design ideas.
We make every effort to link to original material posted by the designer. 
Please let us if you would like us to link to or post your design.

HOME Schematics Index Hobby Corner Dave's Circuits Electronic Resources Contact Info
Imagineering Ezine    Discover Solar Energy Dave Johnson & Associates Faraday Touch Switches

DiscoverCircuits.com -- Hobby Corner
Last Updated on: Thursday, November 16, 2017 06:30 AM

Hobby Circuits List

The contents & graphics of Discovercircuits.com are copyright protected.
LINKING to Dave's circuits is permitted but DO NOT COPY any files to your WEB SITE server

More  Model Train CircuitsLED Circuits; Flashing Lights; Models

HO Train Lighthouse Flasher Revisited
December 16, 2012
designed by David A. Johnson, P.E.

HO Train Lighthouse Flasher Revisited
HO train sets often have authentic looking scale model homes and buildings.  A while back someone asked me to design a flashing LED light, which he could mount inside a model lighthouse and have it operate so it would appear to rotate and flash.  I designed a working circuit but I was never pleased with the results.  Iím still not 100% pleased but the revised circuit below seems to operate a bit better than the older circuit.
The circuit below can be mounted inside a model lighthouse and powered by 4 AA alkaline cells or a 5v to 6v supply.  The circuit drives a single LED lamp with a pulse width modulation (PWM) ramping signal.  The ramp simulates the rotating light from a lighthouse beacon.  The circuit uses two CMOS versions of the 555 timer and a common LM393 dual voltage comparator.  The triangle signals generated by the two timers converge at the inputs to the comparator.  The slow 0.14 Hz lower oscillator makes a complete cycle in about 7 or 8 seconds.  The second oscillator runs at about 10KHz. The PWM output of the LM393 is connected to a FET switch.  The PWM signal at the FET gate causes the average light intensity of the LED to swing from about 5% to 95%, with R4 limiting the current to about 4 milliamps.  At the peak of the PWM signal, a pulse from the lower 555 timer is routed to a second FET switch.  The signal applies a 50ms pulse to the LED through a second resistor R5.  The result is a LED light, which gradually grows brighter, then flashes even brighter before dimming down again. This produces a light, which somewhat simulates a rotating lighthouse light although I think a llogarithmic waveform would produce a better intensity ramp than a triangle waveform.   Perhaps that feature could be added later.
 
HO Train Model Lighthouse  HO Train Model Lighthouse

Click on Drawing Below to view PDF version of Schematic

HO LightHouse Flasher Revisited designed by David Johnson, P.E.

More  Model Train CircuitsLED Circuits; Flashing Lights; Models

Hobby Circuits List
eMail David A. Johnson, P.E. about this circuit

 


HOME Schematics Index Hobby Corner Dave's Circuits Electronic Resources Contact Info
Imagineering Ezine    Discover Solar Energy Dave Johnson & Associates Faraday Touch Switches


 About Us   |  Advertise on DiscoverCircuits.com   |   Report Broken Links  |    Link to DiscoverCircuits.com  |    Privacy Policy

Copyright  2002 - 2015 David A. Johnson & Associates.  All Rights reserved. 
 Linking is ALLOWED but COPYING any content or graphics to your web site is EXPRESSLY PROHIBITED.