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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
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
