SC1 AND SC2 SWITCH CONTROLLER QUESTION

The SC-1 is cheap for a reason.  As long as you practice replacing TO-92 package triacs, you're all set.   They do work for switches, but I've had to replace the triacs on a number of them.  I bought a few cheap, and after a handful of triacs, they're all functional.  The triacs are only rated at 600ma continuous, though they manage to handle the surge of the switches.

The SC-2 has real 15 amp relays that are robust, so it's a lot harder to damage those.

Hello

Much thanks for the reply. First of all, what are Triacs and how can they be replaced ? Where can I get them? The three SC ones I have are used so how can I tell if they have blowin Triacs ? I plan to use them for switches only. Is this okay?

Much thanks again, Jerry

This is a triac, at least the ones in the SC-1.  It's a three-pin TO-92 package part on the circuit board.  There's two for each channel, they're the most common failure for the SC-1.

You can tell they're probably blown if that channel doesn't work.

MAC97A8

Here's the circuit board and where they are located.

Hennings Trains

Thanks for the candid explanation of the Lionel SC-1 vs. SC-2.  The local train club (Central Arkansas Model RR Club) here in Conway, AR, intends to add a Lionel Switch Controller to its 20x26-feet O-gauge layout to activate four yard switches.  We'll be sure to buy a SC-2 device. The club installed Atlas O three-rail NS track and O45 RC switches in the yard area and also installed a Lionel 180w PowerHouse, Lionel TMCC-Legacy Command Base, and a CAB-1L.  As I understand it, the SC-2 picks up and responds to the TMCC-Legacy signal carried by nearby tracks. Power to the SC-2 would be applied by a connection to a nearby track section inasmuch as a constant 18v source would be available there; a separate power supply for the SC-2 is not necessary.

Mike M.
(ritrainguy)

You don't need a separate power supply if  you use track power.  Also, if you want to use all six channels for switches, there is a simple modification to remove the extra ground from channel #1.  Cut the trace indicated that is next to the aux power and the channel #1 connections.

Much thanks for the information!,

Jerry

By the way where do I get Triacs and how much do they cost?

Jerry

Jerry A posted:

By the way where do I get Triacs and how much do they cost?

MAC97A8 Triacs at Digi-Key

If you do eBay, dozens of listings such as ...

I buy them from the link I posted, they're 32 cents when I buy 10 or more, which I always do.  I also batch them with other parts, so shipping is a non-issue.  Digikey only charges actual First Class shipping on small orders.

I asked my older brother who is a EE about triacs and this was his response:

A triac can be used to turn AC on and off when used in binary mode or to adjust voltage if used linearly.  The most common place that a triac is used in a house is a light dimmer (or transformer).  It can be used to turn off the AC as the sign wave amplitude gets larger limiting the voltage and making the light bulb dimmer.  It can also be used to do the same in a transformer (or external to one like we used on dads old transformer).

It can also be used to adjust voltage or turn it on or off in other parts of the train set.  Within an engine if it has motion control, turn lights on or off, etc. 

The one shown on the link (ebay) is not in a heat sink case so it doesn’t look like it can handle much power.

No new information there, Harvy, the traics I specified are the ones that are used in the SC-1.  You could probably tinker around with some replacements and get a little more power handling, but what would be the point?  If you need more power handling, buy the SC-2 with the 15 amp relays, they're a much better solution!  These are the same traics that are used on the R2LC and R4LC as well for lighting and couplers.  They're sized to the task, and they work fine when used as intended.

If I need more power handling, I design for more power handling.

Another comment from my brother that may be helpfull:

I see from the picture there are no heat sinks. You can also get little metal heat sinks in various shapes that clip on the device.  This will help a lot if they are operating on the edge of designed power handling.

Yep, there are TO-92 heatsinks, however you have to look for a style that will fit.  I know for the R2LC/R4LC, it's a pretty tight fit.  Here are a couple of common styles.  Obviously, the center one is designed to be bolted to a chassis or other heat sink source.