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Controllers off mini lights (racing style)????


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I asked this over in lights lights lights but no one has anything to offer so maybe one of you guys or Dan might know??

So, I have a simple 4 output (racing NOT multifunction) controller from and old mini light string

I wanted to use it to animate a display however I have a few questions.

I found that all four outputs remain on and they all flash off at different times but all with the same period.

I wanted them to flash ON in sequence so my logic is reversed. Decided to hook up some AC relays (DPDT) to allow me to reverse the logic.

I found that the relay alone would come on but would not turn off UNLESS I added more load to the output (put a light on there in parallel with the AC relay).

I dont understand why this is.

BTW.....MY LOR will control the relay just fine with no additional load.

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That is one of the potential problems with inductive loads (like your relays) being controlled by a circuit that is designed to be used with resistive loads (like lights)... Your solution with the lights in parallel should work.

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Turns out I cant do what I want...this thing overlaps the "offs" so I can not do the animation I need. Looks like I either need to use the LOR or buy something else for this task....

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OK, Tonight I set all this up using a simple 4 channel shadow racing style mini light controller from an old set.

Since I needed 3 off and 1 on I needed to reverse the logic so I took the outputs of the controller to 4 AC driven DPDT relays.

When driving the relay by itself the controller would turn the relay on and never turn it off. Adding a 40W bulb in paralell witht he relay did the trick and the logic worked.

I assumed some lower wattage bulb would work with this (4w nightlight bulb). It did NOT work. Only the higher load will work apparently.

I also found the inductance of the relay coil to be 0.6 henrys. At 60hz and 11uf AC rated cap should negate the inductance. I only had a 2uf cap rated for 200V and it did not work when I put the cap in parallel with the relay (On second thought, this should have been in series with the inductor..? I forget?? Anyone?.

Anyway, somewhere in my trials I blew the first channel of the mini controller. I guess these things aren't too bullet proof.

Bottom line, if you use a 40W bulb then this method should work. You can buy a controller for about 60 bucks Neglecting time, you should be able to put this together for 25 or 30 bucks by the time you get your relays, spade connectors, wire wood for a mounting surface. Probably not worth the effort unless you have this stuff laying around.

Also, you will have 160 watts extra running in bulbs you have to hide and the sequence is not exactly 3 off and 1 on...its more like 1.5 on and 2 off as the sequence overlaps the previous step.

Anyway, I"m not sure what I will do at this point. Scrap this and buy what I need or try something else. Any suggestions?

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  • 2 weeks later...

I did a little circuit analysis and found that the AC relays (600mH) WITH the resistive component (about 4Kohms) does not present much of a phase shift between the voltage and current through the relay. The current phase shift does become significant if the resistance was 50ohms say.

This leaves me a bit perplexed as my 4W bulbs wont allow the SCR (half wave rectifited) to switch OFF. It requires a 25W bulb to allow the SCR to switch off. This isn't even a holding current issue? There is a dV/dt issue that can hold triacs on but thats due to inductive loads also which analysis shows is insignificant on this AC relay. (unless I'm doing this wrong).

Funny, my LOR switches these guys just fine (which I'm glad of becuase that was their intended use).

LightORama wrote:

That is one of the potential problems with inductive loads (like your relays) being controlled by a circuit that is designed to be used with resistive loads (like lights)... Your solution with the lights in parallel should work.
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