# HO DC Simple Reverse Circuit



## T-Man

Update, this is the first thread. The second thread is complete and uses a walwart power supply to keep it simple.
Here is the link

I have seen this question at least twice in the forum and thought I would expand on it. Using our new resource from Bob Paisley (let us give the guy some credit here) has a circuit for a simple reversing circuit used for a trolley.
http://home.cogeco.ca/~rpaisley4/AutoRevCheap.html
For Parts
Old transformer with ac accessories output with a least 16 volts
DPDT 12 v relay 275-249
555 timer
LM7812 12v voltage regulator 276-1771
3 capacitors 1uf (272-0996),100 uf (272-1028), and 330 uf (not in stock) (I used a 470uf. 272-1030)
A 10 k resistor. (This is not used since I did not use pots.)
6 1n4001 diodes. ( I went with a bridge rectifier. 2726-1146)
R1 and R2 are shown as 1 million ohm potentiometers or pots ( not used)
Availability at radio shack? They should stock the timer, regulator,resistor, and the diodes. I need to check on the capacitors and the pots if you use them.
The illustration discusses R 1 and R2 and how can substitute different values and get desired results.( I used a 470K resistor for both.)
( I did not use the pots)
I am going to start with the pots. They are varable resistors so you can change the timing. (I went with a 70 second one way and 35 second return) 
First problem is how to wire the the three prong pot when the diagram shows two. Heres how.
Refer to figure 6 third picture, the variable resistor. It shows you how to connect 2 and 3 to ground.
http://sound.westhost.com/pots.htm#pots-knobs
One setback is I don't know if it is directional and what side the ground should be.
Pots when purchases have the leads numbered 1,2,3. One is ground ,2 is output, and three is positive. It is very much like the voltage regulator. Positive on the left, output in the center and negative on the right when facing the screw or stamping. I guess I will have to wait to test it out.

Resistors R1 = 0 and R2 at 500k Will give a 34 second run and a 34 second stop
I played with the calculator and with R2 at 250 k you get 1 17 sec run and a 17 sec rest.
With R2 = 100k you get a 7 sec run and a 7sec stop
With R1 and R2 at 500k you get a 69 sec run and a 34 second stop.
I would think a short runtime would be more desireable. 34 seconds is a long time. ( I went with R1 and R2 at 470k resistors)

Now, What if the trolley gets to the end fast. Now this is interesting. you rig the track with a diode so the trolley wil go only in one direction. When the trolley hits this space it will rest until the cycle reverses. So 35 seconds to get there it stops for 35 ,and then returns for 35 ,stops and the cycle repeats. So travel time must be less than 35 seconds for the trolley to reach the end before the reverse kicks in.

Time for a break. I may more editing but this is it until I make one.
The 330 uf capacitor is not instock I may go with a higher in the 470 range.All the other parts are there. I did test the 470 uf capacitor on a bread board and still got the 12 volt supply.
Bob


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## stationmaster

I am so lucky to have a "smart" layout. The decoders "sense" the change in polarity and adjust accordingly. My soldering skills are below the "sucks" level.

Bob


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## T-Man

Thanks for the chuckle:laugh:
I started mocking up a diesel horn circuit today.More to follow later.
I got a monotone horn from the breadboard mockup. Had a few mixups on assembly.

I thought this thread would be of interest. One could even use it as an argument to go to DCC if they can't solder. 
Anyway I am trying to build one for my friend Matt just to prove it's doable and get some pictures.
Bob
For soldering, when it gets ugly I use thin wire and then clean,tighten, or replace the tip.
Make sure it's in a box when competed.


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## T-Man

*Update*

So far I have made two units. The simple circuit is are not simple. The real problem has been reading the circuit diagram. The voltage regulator is shown with connections that are reversed. Causing confusion. The first had errors in the power supply and cooked some parts. It has more wires because I attempted corrections. 
The second is not done. It has a timer problem. The power supply has giving me problems but that is solved. I mocked up both, the timer and the power supply. All I need is to get them working at the same time. I am confident I do not have a connection problem. The parts are were they should be. I have to start testing the parts.
I fixed up a building to house the unit with lights and directional lighting. 
I went with 18 gage wire on the relay for the track. The track feed is in red.
I corrected the first post marked in parenthesis with my current substitutions.
The second picture has the relay on top, the power supply to the right, and the timer on the left.The bridge rectifier is the thin black object on the right.










The right picture is a bread board set up of a two tone diesel horn. It works but reminds me of a Vokswagen beetle horn.


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## T-Man

*Timer vs Power supply*

I retested the timer with my newly fixed 12 power supply and it worked. One chip was toast. SO my guess is the power supply is not reliable. I may go with a 1000 cap and a 100 uf capacitor ( The same setup I used to modify an old the power supply.) Like what I used in the power supply. I figured out how to wire the directional lighting. The red is on when the relay is on and the green is on when red is off. I connected the green from three -to four + on the 555 chip. Three turns negative when off. I used a 480 ohm resistor to protect the LEDs.
Orientation of the chip as shown.
........................8765
........................1234










These pictures are not that great for reference. I get confused looking at them. Some of the connections on the timer are not visible. One capacitor on the power supply apears to be facing in the wrong direction.
To explain the bread board. The chip has a jumper from 2 to 6 and 4 to 8.
7 has two resistors of 450 k to 6 and 8 The 100 uf capacitor goes from 2 to one. Negative arrow toward one. Three goes through a diode to the coil. 1 goes to the other side of the coil with a diode between the coil connections. The siver bar of the diodes point to the coil connection of the the number 3 connection. The Led will go from 3 to 1 when the coil operates it will light, and when off the Led at 4 to 3 will light.


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## T-Man

*Power supply*

This is the 12 volt DC power supply connected to an AC power supply. The Circles are the capacitors. 1000 uf and 100 uf Left and right. The negative(black sides ) face inward. The 12 volts come off each side of the 100 uf capacitor The green line is negative and the positve is the out side of the 7812 voltage regulator to the 100uf capacitor. My problem is that the diagram shows the reverse order. I was suppose to know the difference DUH! This should clear that up.












I am thinking of setting this up on the table to give it a test run. Table adjustments will be needed.
Power supply is made up and works with 11.87 volts.


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## T-Man

This project hasn't died. I have the L set up with a DC transformer and my DC LASER switcher in O27. The AC engines won't reverse without an eunit but HO engines are fine. AS a matter of interest the AC engines run on DC but won't reverse at all. No matter which direction you point the engine it will go in the direction pointed. I may tinker later with this but this is a DC project. Next step is to add the timer but my local train vendor is moving today so I am assisting. Later.


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## T-Man

*Side Track*

The electronic switch circuit is easier to troubleshoot when it is attached to a directional light. I set up a two sided light. The LEDs are standard Radio Shack from their assortment package 5mm. I placed a red and green in series and the second set opposite in polarity so only one set lights at a time. and the feed had a 470 ohm resistor.










Depending on the current direction only two LEDs will light up, one on each side. Then you play wit the two leads to make sure you train is going in the green lit direction (facing the engineer). 










The LED positive side is the long lead.
Round LEDs have a flat side at the base , this indicates the negative/short, lead
The tower will be homemade with a 1/2 inch PVC pipe for height and 5/8th for the top. Not exactly a scale model but it will work.


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## T-Man

*Directional Light*

A made a tower for the Directional Light . I previously had added something similiar to an HO structure with 3 mm LEDs. These are 5mm . This track does have DC power. I used water caps for the light housing. I didn't need any glue to hold them on.










A 5/8 butterfy bit made a perfect fit into the wood for the PVC.
SO a three dollar LED assortment. A 470 ohm resistor, wire 22 gage, and scrape pvc/wood.
Another angle.


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## T-Man

*Power Supply*

Gee, I guess I take my time. I started this in February and am almost finished. I did redo my train table. Anyway I soldered the diodes in the track and tested fine. I used a larger 3 amp capacity ( 1N5400 Radio Shack 276-1141)since the motor may draw 2 amps. The track is rusty but have been cleaning and using it to get the stall points out.

The timer now has some block terminals I got from ebay. My brother gave me an idea to use a Brick. A brick is one of those techno terms for the black power supply we use so often.I find them at yard sales for a dollar. I couldn't build them that cheep. 

The selection was tricky I tested a 12 and 9 volt DC power supply. With a meter I got 17 and 14 volts from them The 9 volt tested fine and worked the relay. I just had to make sure I conected the positive side correctly to the timer. It has 480 milliamp output. Next test is install and test run.









I guess I don't need weathering on the track.


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## T-Man

*Success!*

It Lives! It survived a test run. I got some video clips. The Simple Circuit has been an adventure. I wil post when I can get the editting done.
To recap I have A DC Lionel Locomotive on an L shapped track. At each end I have a diode to stop the incoming engine. I have an tower to tell me the direction and all is working. I have a board powered by a brick. And a DC transformer fed into a relay on the timer board to reverse the current and have the engine go back and forth. The timng is 70 seconds one direction and 30 seconds to reverse. Due to the corrosion on the track I had the speed up to prevent stalling. Remember the transformer shuts down the engine but the electroncs will work as long as the brick is plugged in. A s witch may be in order here.


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## T-Man

*House Cleaning*

These pictures show my first two attempts at the reverse circuit. It was actually the third try that made the video. Recently, I redid this thread to improve the explaination. 

I went back to review the first two boards to see the problems. To make it simple they both had badly sodder joints (or should I say unsoldered?). For now, I gave up on the power supply and use the simple wall plugs. I wil say they have worked out very well.


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## raleets

I sure admire all you technically-bright guys who can create that neat stuff from scratch. A true talent, and one I don't happen to have.
If it comes in a box then I'm all over it!
But many thanks for the info on trolleys. I kind of figured there was some type of internal switch that caused the little bugger to reverse itself and head in the other direction. Kind of like the wife when I tell her I'm about to spend some more money on my trains! :laugh:
A happy wife is a happy life.
Bob


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## gunrunnerjohn

Most trolleys that reverse indeed do have a switch that hits the bumper and reverses. I have one that has the bumpers and an electronic E-Unit as well.


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## T-Man

This circuit has a wide range of scales Too. It is DC dependent so some Lionel works with it, but HO N and others will work also. For some reason we had a rash of requests on how to do it, this is the result.

Updated version: just connectors, relay, chip two resistors and the capacitor. The other pictures may be scary.


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## gabrielrb

*automatic reverse circuit*

hy alls
I but a trolley Ho and I wish built a reverse automatic circuit but I not whow are this.I live in Colombia,please pardon my bad english..Please teel my about this and wiring diagram.
I have 2 micro switch and 1 latching relay(here send)Thank you very much for this favor.
Best wishes
Gabrielrb


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## gabrielrb

*automatic reverse circuit*

hy alls
I but a trolley Ho and I wish built a reverse automatic circuit but I not whow are this.I live in Colombia,please pardon my bad english..Please teel my about this and wiring diagram.
I have 2 micro switch and 1 latching relay(here send)Thank you very much for this favor.
Best wishes
Gabrielrb


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## wvgca

gabrielrb .. your image shows a standard relay, which is different than a latching relay?? just use a resistor that is sufficient to keep the relay energized .. then one end switch to 'break' the circuit, to reverse power, and micro on other to 'make' again .. my auto reverse test track uses the same, works okay


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## gabrielrb

*to wvgca*

Dear Wvgca:
Thanks by write to my.It is possible send to my a wiring diagram.Thank you for this.
Best regards
Gabrielrb


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## gabrielrb

*to wvgca*

Dear Wvgca:
Thanks by write to my.It is possible send to my a wiring diagram.Thank you for this.
Best regards
Gabrielrb
Beautiful maquette


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## wvgca

i never did do a wiring 'diagram', just put it together


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## gabrielrb

*to wvgca*

Please pardon
Gabrielrb


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## T-Man

Posts number one has a link to the circuit diagram




Mensajes número uno tiene un vínculo con el esquema de conexiones


This is the link to google translate.

Este es el linkt a google translate


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## T-Man

I do have another version of this circuit. A man was at the LHS and wanted a circuit to start and stop a train that runs in a circle.

It got me thinking. The timer has 1 minute in one direction and 30 seconds the other. WIth no diodes on the track the train would circle. Now place a slide switch on the relay. So only one output would work. The train would travel I minute and stop for 30 seconds. Or travel 30 seconds and rest for one minute.


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## DonR

That system is a Cadillac. Makes for nice realistic starts.

My system is more of a Yugo.

I'm working with a guy to use a simple 2 coil latching relay
to reverse the polarity on an HO DC track that will have a loco going
back and forth. It'll hit a microswitch on each end and take
off going the other way. 

Don


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## wvgca

DonR .. easy to do, that's what mine is ...but even simpler, standard single coil DPDT relay, two micro switches with paddles on each end of track, and wall wart for relay power, only part that requires any precision is the hold resistor... enough to hold, but not enough to move / latch in ...and ordinary DC train transformer to make the loco move, never did make a schematic, or look for one on the net, just built it... lol


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## T-Man

I see, yes it is simple. I like the delay feature in mine. How do you stop before reversing? Doesn't sound good for the motor.


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## wvgca

Well,it doesn't stop, no provision for that .... just reverses, it's fine for newer style motors, the only ones that it can be hard on are the old style open frame motors with AlNiCo magnets ... the magnets can be weakened by abrupt flux field reversal, but I don't run the DC transformer at a very high voltage, just enough for the loco to move back and forth .. but component cost as well as complexity is very low, and sufficent for occasional usage


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## T-Man

I was thinking about the stress on the drive gear, but that would be on the cheep pancake style motor.


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## wvgca

T-man .. i actually never thought about that, lol .. yes there may be some due to reversal without stopping, but I run pretty low speed on the back and forth reversing track, it's not even three feet long ... I don't use it much anymore, have a three foot circle of Atlas 100 brass track on a piece of 1/4 plywood, and an old DC transformer mounted that I use more often, if it doesn't run there it probably won't on my layout as I think I have one or two turns that are closer to 18 than 20" radius there ..


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