Using illuminated switch to control LED lights.

[trader_4]

The impedance would be 56 ohms and the resistor part is 470 ohms.

[gfretwell]

We used similar RC nets on AC stuff all the time. If you are really talking about DC, a diode is a better solution.

[Dean Hoffman]

No, I haven't in any scientific sense using meters and making comparisons. I based it off practical experience and amateur guess work. A forward control wire powered when the pivot is running in forward will supply a tower micro switch which tells that particular tower it's time to move in forward. The switch releases, supplying 120 vac to a three phase contactor coil. A reverse control wire will tell the particular tower when it's time to move in reverse. Putting power to the reverse control wire when the pivot is running in forward can make it reverse, or vice versa. The systems would change direction sometimes when they weren't supposed to. We found that putting those suppressors in the computerized control panels seemed to cure this. The factory has been putting some form of these suppressors in the tower boxes since the 1970s. They wire them across the 120 volt contactor coils. Our parts books call these things suppressors. I'm sure not knowledgeable enough to say otherwise.

[Clare Snyder]

May work VERY well for that application - but I'd bet pretty heavilly against it having a positive effect in the case being discussed - where, from my experience, NOTHING is required.

[Dean Hoffman]

It was a big enough problem that the factory (Valley) started shipping a kit to fix it. Part of the kit is a surface mount light socket and what some called a hand heater that's screwed into the socket. It's shaped roughly like a cylinder of a toilet paper roll. The heater is wired through a relay to take stray power from what's supposed to be the dead run circuit. No idea why one of us tried the suppressors. Probably because we don't know any better and didn't have the factory parts. They seem to work. Fretwell's comment about them preventing voltage spike across contacts makes sense. They're in every tower box to reduce the wear on the run micro switches that start and stop the towers. Some version of them has been in tower boxes since the 1970s, well before any control panels had computers.

[gfretwell]

If you look at a 3890 check sorter you will see over 100 similar RC nets, for exactly the same reason, to protect the switching device from the coil collapse. Even electronic switching devices need them in spite of the fact that they are supposed to switch on the "zero crossing". We suspect it is because there is no real zero crossing on a line to line 3 phase load. (there is no neutral in a computer power panel. All loads are line to line). On the 3420 tape drive they were constantly tweaking the RC net for a big solenoid that operated the transfer valve. We kept burning them up. The final fix was a motor start type capacitor (big silver can) and a 1 watt carbon resistor.

[Clare Snyder]

Just to be clear here - we are talking about illuminated light switches controlling LED lights - right??? I know there is a lot of subject drift - but the original discussion, to which I am responding, has no inductive loads, no relays, no directional control,and no "irrigation systems" or "tower boxes".

Somehow someone came up with the idea of putting a "suppressor" in a lighting control circuit utilizing a self-illuminated switch controlling LED bulbs - - - -

I have numerous illuminated switches opperating LED lighting (both dedicted and converted luminaires) with no problem (with either the lighted switch or the controlled lamps).

Just for "clare"ification!!!

[Clare Snyder]

Actually the "final fix" was doing away with nasty things like tape drives and DASDIs !!!

[gfretwell]

They still have plenty of DASD, it is just 3.5" disk drives packed into a rack as tight as they can get them and not burn up.

It is still the same thing, only in a smaller box. Direct Access Storage Device

As opposed to an ISAM file like a tape.