Don't forget the two diodes. Any small silicon diodes will work, such as the common 1N4001. And make sure the relay coil is 15ma or less.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Very true. I think i will go with the NCE Switch-It and small relay. Thanks for the input.
Philip
Well, the Aux-Box is $150 and that's just relays, so the LS-150 is cheap relative.
You'd need to build something yourself to get lower cost, the relay and couple of diodes with a basic Tortoise machine stationary decoder, like the NCE Switch-It. Hardly anyone makes a stationary decoder with just 1 output, because it makes no sense - even the smallest microcontroller has ports for at least 2 and often 4 outputs.
If it's cheap or not depends on if you're a Gates family member, or me. I'm not on a super tight budget, but the LS-150 has 6 outputs, and is $80.00. What do we have for about 20.00 ? It looks like it would work well, but I would need to find a use for the other 5 outs.I understand about the diodes, but how would you know what a stationary decoder will handle power wise in order to size the relay? I don't know the draw of the supplied motor for the bridge, but according to the article excerpt above, it varies from 70 to 180 ma.
Thanks,
You may be thinkign of the Aux-Box. It's basiclly an accessory decoder with 8 relays. Problem is, it costs more than the bridge. Plus there are 7 extra relays then.
A pair of diodes, one across the relay coil, and one in series witht he relay, should work with any always-on stationary decoder (ones meant to drive a Tortoise). The parallel diode is to supress the BEMF spike fromt he relay coil, and the series diode is so that when the output is reversed, the relay cuts off since current flow would be blocked. Just find a relay with a 12V coil and a current rating below what the decoder of choice can supply - most meant for a Tortoise are 15-20ma tops, but you can find relays with this rating. Another option might be to use a Lenz LS-150. Even in "stall motor" mode, it still cuts off after a time delay, the longest delay might be enough for the bridge to completely raise or lower and hit th elimit switches, plus the LS-150 can drive more than the typical Toroise load. Have to check the bridge motor current draw, but it may be enough to directly run the bridge. Basically bypass the control switch and hook the bridge motor and limit switches right to the decoder. LS-150's are pretty cheap, so even if none of the other outputs get used, it's not a huge deal.
I was thinking that it's more like a turntable. I don't have this bridge, so my reply was based on conjecture.
If it already runs kind of by itself, with limit switches built in, then yeah, a stationary decoder is the way to go.
Didn't somebody have a DCC accessory that was just a set of contact closures that could be controlled by a throttle?
It takes an iron man to play with a toy iron horse.
WHy wouldn;t you want a stationary decoder for something like this? The bridge is effectively emulating a turnout - in fact the open and closed terminology is exactly appropriate here. This thing only turns about 90 degrees and then back. Driving it with a motor decoder seems way too involved, vs just pressing a button and letting it do its thing.
The motor decoder idea does make a lot of sense for a turntable bridge, more so than Walther's clunky way of assigning a turnout address to each stop that gets programmed in. Just select an address and have the speed curve set so you get a traverse speed and a jog speed - speed steps 1-5 or so as jog speed, anything higher all set to the same traverse speed.
Edit: OK, up and down - there are too many Walther bridge threads going on around here!
You really don't want a stationary decoder. You want a motor decoder. Wire the bridge motor to the motor leads of the decoder. You'll even have some extra functions for lights if you'd like to add that.
All you need is a simple decoder like a DH123. You can set the Max Voltage CV to limit the output, and you'll even have the ability to play with acceleration to get more realistic motion out of the bridge.
My only concern would be with applying the pulsed DCC signal to a 6-volt motor. You might need to add a resistor in series with the motor to limit the maximum voltage.
Randy, I have some switch machines that I made, with 6 volt motors. on some of them I used a transformer with some diodes which resulted in about 5V through a relay. Maybe I could use that same power supply through a relay as you suggested. Thanks for the help.
Rich, I'm not a wizard, but I do well with smaller electronic projects. Thank you for the link.
That's certainly one way to do it, just drop the voltage. Might be simpler to have the stationary decoder drive a small relay which simply takes the place of the existing switch.
Be advised, this bridge has a six volt motor. Decoders put out 12 to 14 PWM. Positive or negative pulses. Wider pulse, faster the motor turns.
Look at the below link.
http://tinyurl.com/nd68b66
I am assuming you have electronic experience.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
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What I would like to do is operate a walthers bascule bridge with an MRC wireless handheld. how it works now is 4 d cell batteries running thru a dpdt switch. I have no experience with stationary decoders. most of the boards seem to made for tortoise. I'd appreciate it if someone could point me in the right direction.