Alternating Flashing Lights

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Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=25593
Printed Date: July 15, 2025 at 1:11 AM

Topic: Alternating Flashing Lights

Posted By: atwageman
Subject: Alternating Flashing Lights
Date Posted: January 30, 2004 at 9:20 PM

I am in the process of building a wig wag circuit using a diagram from David Levy's relay application guide on page 24, 6th edition. My question is what would be a good value for the rheostat to use. I may use instead a fixed value wirewound resistor. I will be alternating flasing two 50 watt lamps. Any ideas would greatly be appreciated.

Replies:

Posted By: Teken
Date Posted: January 30, 2004 at 11:37 PM

Anything which will handle at least 30-40 amps. Technically speaking, it will only require the unit to be 8.33 amps for the rheostat.

But there is a fudge factor, which needs to be addressed assuming the circuit, and its wiring are not up to task.

Regards

EVIL Teken . . .

Posted By: atwageman
Date Posted: January 31, 2004 at 5:07 AM

Thanks for the help. The wiring etc will be up to task. In your opinion what value in ohm's should the rheostat be? thanks

Posted By: Teken
Date Posted: January 31, 2004 at 2:48 PM

Here, I will do you one better. I will show you how to make a rheostat. The basic principle is the same. Once you have found the resistance to which you like in terms of the flash rate.

Then you will simply tap the coil winding to that point via soldering. I know the reason for the rheostat is to have the ability to adjust the flash (rate) pattern.

But once the novalty has worn off, you will realisticly, leave it in one place. At that point you may use a fixed resistor to perform the exact same function.

So to answer your Q, there is no fixed value of resistance to which applies. Only when you have found the resistance which provides the amount of on-off duration you like, that is the resistance you will implement into the circuit. The wattage of the rheostat would however be from anywhere from 50-100 watts, the reistive values range from 1 ohm, to 100,000 K ohms.

Regards

EVIL Teken

https://www.energyquest.ca.gov/projects/rheostat.html