DPDT Momentary (ON)-OFF-(ON)

In the Silicon Valley area:

Halted Electronics Central & Lawrence

Sorry, that's not much help if you aren't in the Northern CA.

Try:

Minatronics is a bit on the expensive side.

Paul

You don't need DPDT (Double Pole Double Throw) but rather the SPDT switch will do well. There are a lot of suppliers of used/surplus electronics out there as well as such places as Mouser and DigiKey and JameCo that will supply the switches. As to size, even the small ones will work with some of the twin coil machines but the larger current ones work longer before failure. I'd do a google for "SPDT toggle switch" and see who has them at the best price. Current capability is paramount here and any voltage will do well.

-- Bob May Losing weight is easy! If you ever want to lose weight, eat and drink less. Works every time it is tried!

Nothing of a DPDT Momentary sort online, Paul, but thanks for the ideas. It may be that their walk-in inventory is more varied than that which they list on their sites.

- Bob

Look at:

Correct. I'm using the other pole to drive indicator LEDs. Could go either way.

- Bob

If you are talking about Halted (HSC) you need to stop by and pick through the parts bins. I'm pretty sure that's where I picked up the last dozen.

Paul

I have quit using the switch to carry device current. I now buy small, inexpensive switches and use them to control the few milliAmps of current needed to actuate a relay coil. The relays are suitable for current in excess of that provided by the power supply and are often less expensive- not to mention easier to find at almost any auto parts store- than a suitable switch. The switch never sees much more than

20 mA and the relays will last longer than the Energizer Bunny. After all, they are made to survive in the engine compartment of an automobile.

Captain Handbrake

Ever thought of using a four position/3 (or 3+) pole rotary switch? Use the inner two as passing contacts, the outer two to light a LED to show turnout position. Now, I realise that using this method to indicate turnout position may freak out some, conventional wisdom being that you should use the turnout itself to "prove" the linkage has actually thrown. Well, I can see that, but (ahem) how often do our turnouts NOT throw when we press the button or throw the switch? Less than 1%? And even then, what happens if you try to cross a turnout set against you? In most cases, just a short. Sounds like a good trade-off to me for much more simplified witing!!

Extra poles on the switch can be used to spread the current load, signalling, interlocking, etc.

Steve Newcastle NSW Aust

Bob

Yes, you got it right, positions 2 and 3 on the rotary switch are "passing" contacts as the selector is not left on them, but keeps going to limit of travel. The arcing problem can be either ignored - I used to use el-cheapo momentary normally-off push buttons, which probably arced to their hearts content. Didn't seem to cause any problems - or you can use unused poles on positions 2 and 3 to gang the contacts which would halve (at minimum) current flow.

Useful things, rotary switches, even on a DCC layout. I used an old 3 position rotary from a previous cab-control* layout instead of a DPDT switch to the program track. The extra position enables me to run a small 0-12v controller, very useful for testing locos prior to decoder install.

Steve Newcastle NSW Aust

• - soon, very soon, we will have people asking "What's cab control?". We have had DCC now for at least 10 years..

Won't work as the switch will return to the center off position and the LEDs would then be off. Besides, if you really want an indicator, the return of the indication from the turnout motor is a much better idea. A SPDT contacts at the turnout which switches between a voltage and ground will drive the LED indicator at the panel quite nicely with one LED connected to ground and the other to the power.

-- Bob May Losing weight is easy! If you ever want to lose weight, eat and drink less. Works every time it is tried!

Without a latching relay, you're right, an DPDT alone won't work.

I don't follow "SPDT contacts at the turnout..." Switch motor driven?

Thx.

Yes, most switch motors have at least one set of SPDT contacts and many have more than that. Put power to one contact and ground to the other, making sure that the contacts are break before make (the wiper drops contact with one contact before touching the other one else you get a nasty short), and you have the wiper telling you which way the switch motor is. At the control panel end, you setup a pair of LEDS so that they are both lit somewhat dimly with the power on and you then put that wire from the turnout to the junction between the two LEDS and one will light while the other will go out.

-- Bob May Losing weight is easy! If you ever want to lose weight, eat and drink less. Works every time it is tried!

try these guys...................

#51-219

best >Any recommended source for DPDT Momentary (ON)-OFF-(ON) switches

Great resource. Thanks!

- RWM