I would suggest

I would suggest Roundhouse/MDC tender wipers.  I think they were set up to wipe the axles.  One of the modular club member uses them with the trucks on his steam engine tenders reversed so that the front truck picks up from one side and the rear truck picks up from the other rail to complete the circuit.  I think I would use a rechargeable AA or AAA battery to power it, but the only Fred I will use will be the name of the conductor in the caboose!

another approach

I have seen this done in N scale using a watch battery with a hidden switch to turn FRED on and off.  It is claimed that batttery will last multiple years.

Batteries...Really?

I am somewhat surprised to see batteries being suggested, although the rechargeable idea had crossed my mind too.

I assumed the best way to do this would be to use the power available from the tracks rather than a battery.  Any specific reasons why you think a battery would be better?

Thanks for the input!

Proto Power West. . .

PPW offers a FRED in HO:

http://www.ppw-aline.com/EotDevice.htm 

EOT Device

brothaslide,

Thanks for that link.

I think the EOT device they sell is a  bit pricey considering what it really is but their method of mounting the electronics in the truck is very interesting.  Making me wonder if I can fit the 555 IC, diodes, caps and resistors into a truck making it useful for flatcars too!  I'll bet they are using smd components.

Anybody have one of these they want to take apart and take pictures of. [wink]

Oh...OK skip that I see further down the page a picture of the bottom of the truck...sure enough smd components to make it small enough...

Oh sorry I finally

Oh sorry I finally realize what F.R.E.D.but don't know what the acronym stands for except as an E.O.T device I thought Fred was a conductors name that rode in a lit caboose. I saw a really cheap way to build one(E.O.T)in MRR magazine. As well as an easy way to constantly power it

I didn't mean to imply

I didn't mean to imply batteries were better. I can only assume the battery choice is a viable  option because it is cheap and easy and doesn't require changing trucks, wheels or axles which then may not meet required "looks" nor match the other 49 cars in your unit train.

F.R.E.D.

No Dan, this has nothing to do with residents of Bedrock!  Flashing Rear-End Device I think or maybe Flashing Red End Device?

I have a circuit that is easy to build and for which I have all the parts on hand, although I would be interested in checking out the MRR issue you mention.  Any idea what issue it was in? 

Steve,

I see what youa re saying now.  Yes a battery is a viable option too but ideally power from the rails would be desireable.  Not sure if it is practical yet though.

Green Steam Products

Hi Blue

Have a look at Green Steam Products

They do an EOT kit along with other electronics kits. Price is a lot more reasonable and they also operate by batteries

http://www.greensteamproducts.com/index.html

Green Steam

Ian, thanks for the link.

Yes the EOT device is much more reasonable and they have some other interesting items as well.

Thanks again!

3909 flasher-updated because it's discontinued

The 3909 IC is an 8 pin chip designed to flash lamps and LED's.  I've bought them before at Radio Shack, and the simple circuit is on the back of the card.   That's it.  I've soldered it up to a AA battery, and it lasts well over a year (with no off switch!).   Use an electrolytic capacitor and just watch its polarity.  If you're not brave, you can solder everything to an 8 pin chip socket, then insert the chip.  Flash, Flash, Flash,..........

Update:  per Blue's response, this chip has been discontinued for several years, so I'm feelin' really Old.  Did some research today (12-12-09) and I found no good substitute.   I'll leave the circuit up just because it was a good exercise for me in how to draw and post a circuit diagram, and it's useful if you find a surplus LM3909 or an NTE876.

Blue! Phosphor Bronz sheets for Pick-ups

Blue I'll try to find which issue the F.R.E.D. is in tomorrow Saturday, as it's 1:00 A.M. and I'm headed to bed after this.

Also Phosphor Bronze pick ups are the best 10 Times better than copper or Brass and Micro-Mark sells 5 inch X 7 inch sheets 3 in a pack for $14.50 part # 83100 they are on page 80 bottom left of both their Fall and winter Expanded Format Catalogs. That's enough material for a hundred engines or cars. I've used The Phosphor Bronze sheets for years they work great on all kinds of electrical Appalachians including on switch machines linkage and they take about 5 years of non stop running and sliding on track to wear out and they keep their flex once you set it also it's easy to cut to shape with small shears. Well Good night all

Dan

Thanks!

Don, thanks for the idea.  It's unfortunate that the LM3909 IC was discontinued.  I did find some on eBay and Futurlec has stock on them still but Mouser, Jameco, Radio Shack, Electronic Goldmine, etc. have no stock left.

Apparently the chip only caught on with hobbyists so with limited sales the manufacturer pulled the product.  Too bad as it was a simple way to get a flasher working from a 1.5V source.

I have found a couple of circuits that replicate the function of the 3909, but of course they are not nearly so compact.  Futurlec list the LM3909 at $2.45 each, so I may pick up some to try and have on hand.  I'm still hung up on powering the FRED from the rails but the LM3909 seems like a great alternative.  Thanks again for pointing me in that direction.

Dan,  thanks for the info on the phosphor bronze sheet!  I can't believe I have not stumbled across it in the Micro-Mark catalog yet.  I'm off to check that out now.

I searched for the FRED article in the MR Index and found two past articles that appeared in MRR.  January, 86 and February, 90.  Going to read the articles online for free to see if I need to get a copy or not.

Edit: Oh, scratch that.  For whatever reason, neither of those articles are available online.

Another thought on batteries

I have 6 Rapido (MRH sponsor) N scale passenger cars and four HO passenger cars that use their "Easy-Peasy Lighting" in them, run off of watch batteries and actuated by a reed switch and magnet.  They work very well and don't require any pickup off track power.  I don't think track power is always ideal, either, because you'd be drawing power away from your locos.  Granted, this would be a minute amount, but if you have many other things pulling power as well, it can add up.  Just a thought.

Another thought

And it's a good thought.

It is not my intention to have  a lot of draw on the DCC bus that is not locomotive related.  Any switch machines, lighting or animations would be powered from a separate supply leaving the DCC system to power locos and sound decoders.  The EOT device will draw so little power that having one per train should not be an issue.

I agree, track power is not always ideal.  I may end up using a battery in the long run so I think I will try to get a few LM3909 chips.

I'm curious how the reed switch is activated with the magnet on your cars?  Do you have to stick the magnet somewhere on the car to illuminate the lamps and keep them on?  I understand how a reed switch works with a magnet, just not sure how it is applied in this case.

My experience with reed switches would be having a magnet pass a reed switch, with the reed switch being used to initiate an event that then completes on it's own.  The magnet and reed switch just trigger the event.

I think the advantage of a battery is that it is a 1.5v source.

If you use track voltage, you need to drop it from 14-16 volts down to 1.5 to run the led.  I've found that the new rechargeable nicads work a lot longer between recharging in my digital camera, and they also seem to hold their charge indefinitely until called upon to work.  I've quit using standard batteries in my digital camera completely, and gone entirely to rechargeables.  You could install circuitry in the car to recharge the batteries, but I think that would defeat the purpose of running battery power on your F.R.E.D.  I don't know how much power a dropping circuit to drop voltage from track voltage to 1.5 would use.

I'd like to see a portable FRED

I'd like to see a portable, battery-powered FRED in HO.

The circuit card and battery pack could be made flat and small enough that they could be mounted on the underframe of the car, and the FRED would drop into the coupler.

This way we who are into realistic ops in the modern era could put the FRED on the rear car during an op session. Yes, I'd have to 0-5-0 the car to install the FRED, but I could live with that.

Or if someone would figure this out and write us an article, please contact me - I'll make it worth your while with some extra incentives including payment for the article!

If you use track voltage,

Actually wont it be dropping it to between 2-3 Volts to run the LED?

I figure it will be less than 20 milliamps.

A portable FRED

Ahh...that's a good idea!  Portable so one does not have to use a specific car as the end unit...which would not be very realistic in practice.  Ok battery operated is the only way to go in that case.

The best solution I have seen so far, in regards to compact size, uses the discontinued LM3909.

Mounting should be simple enough.  Having the LED FRED fit in the coupler would take some figuring perhaps.  Making it compatible with Kadee or Sergent would be a consideration too.

Hmm...

Reed Switch

With the Rapido lighting, the reed switch is located on the roof of the car by the roof grabs so its easy to know where to touch the magnet.  And that's all you do - touch the magnet to the car roof and the lights come on.  Touch it again and they go off.  Very simple.

3909 Flasher IC

Don, don't feel bad.  In my searching it seems lots of people assumed this chip was still being made and are surprised that no substitute seems readily available.

I have found a supply of them online I believe, and am talking to my electronics guy to see if he can source them for me as well.

Alternately, I have another circuit I want to try, using a hex inverter IC that is nearly as simple.

My electronics guy tells me there are a couple of other chip options, so I am looking into that as well.

Dave, thanks for the explanation.  The Reed switch latches until the magnet is re-applied.  That works slick.

Flasher IC's

Well, so far it looks as though the best component for a battery operated EOT device is a discontinued chip with limited availability that is becoming a bit pricey as it gets harder to find.

I am looking at other options, using the hex inverter I mentioned but the circuit is a bit more complex and thus more bulky.  The neat thing about the circuits I am looking at is the "charge pump" aspect of the circuit that bumps the 1.5 volt supply up high enough to light a red LED which typically would have a minimum forward voltage of around 1.7 volts to as much as 2 volts, depending.

I have to get a couple of hex inverter chips from my supply guy before I can try the ideas I have.  Once i have them I'll breadboard the circuits and see what they are like.  I am really tempted to grab a bunch of the LM3909 chips if I can source them, just to have them on hand.  They seem like a very handy IC to have in ones parts drawer.  I really don't understand why they would have discontinued them.  I can replicate the chip with a discreet component circuit but it takes 4-5 transistors, a capacitor, a diode and 10 resistors to recreate the circuitry on that 14 pin DIP!

Oh well, having fun all the same.

Flashing LED's

12-13-09:  Well, a little more research into how to flash an LED.  The LM 3909 chip was discontinued because it's really not needed.  3mm T-1 size flashing LED's are available in a variety of colors.  For instance, in the Mouser Electronics Catalog they show red, yellow, or green 3mm LED's for $0.88 each.  Just apply DC power:  3v. gives a 40 second flash rate, and 14v (the max) gives a 20 second rate.

The ref. is on page 134 of the Mouser on-line catalog..

http://www.mouser.com/ProductDetail/Kingbright/WP36BHD/?qs=JPafQrpKLhhHh%252bktbOnE6Q%3d%3d

Flashing LED's

Don,

In reading the data sheet I see that the minimum voltage is 3.5V and that at that voltage the frequency is 1.5Hz.  Now I am no mathematician but isn't that one flash every .6 seconds and at 14 volts the frequency is 3Hz, so isn't that 1 flash every .3 seconds?

I think one flash per second is more suited to mimicking the EOT devices so the rate seems a bit fast for an EOT.  Please correct me if I am wrong about any of this.

The nice thing about the blinking LED's is that they may not need a circuit for flashing if powered from the track under DCC, but the current will still need to be limited to below 20ma would it not?

The other issue with the blinking LED's is the minimum voltage.  Joe is interested in a portable FRED concept that he can attach to the end unit of a train and easily remove again.  With the minimum voltage being 3.5V, I wonder how a battery pack with enough power to light the LED could be easily mounted beneath a car body?

The nice thing about the LM3909 is that it used a charge pump to bump the 1.5 volt supply up high enough to provide the forward voltage of 2 volts the red LED needs to illuminate and at the same time it provided a flash rate of about 1 per second.  Honestly, with this and the other applications I have seen for the chip I think it should still be in production, but what do I know?