HELP - RC servo controller switched by 555 / 4017 traffic light controller circuit

Thread Starter

vtolman

Joined Jan 13, 2017
13
Newbie help needed please.
I made this model 4-way traffic circuit and its working good.
I want to control 2 separate RC servos each switched automatically by the traffic light controller 555 / 4017 board (I'll call it the TLC)

PURPOSE IS - each servo lifts a neodium magnet up under the model traffic lights intersection to stop HO scale model cars (with reed switches inside the cars) at the RED and YELLOW lights independently on each roadway.
I'm trying to make a poor mans FALLER CAR SYSTEM traffic lights - but they use electro magnets which loose magnetism when hot and don't work properly.
There new FALLER digital system solves this but I'm staying analogue for now ... I'm way to green so please no suggestions to do micro controllers / arduinos etc.

The model cars magnetically steer and follow a hidden wire under the road surface.
The cars have a reed switch inside which stops the cars at these traffic lights by those neodium magnets lifted by the servos.
The servos need to travel to two end point positions which I assume I can adjust with trim pots or fixed resistors.

QUESTION 1. Before I make the so called "servo tester circuit" below ... is that a suitable circuit which can wired to and be switched from the TLC ?
Question 2. If so how ?

I assume it needs another circuit which is either a light activated switch (adding extra LED's and a sensor) to turn the servo controller on and off.
The TLC has weird voltage outputs to the LED's from 9.3 to 1.9 to 0.5 and it reverses to - 1.9 etc as the circuit timing changes the lights.
I'm totally new to electronics SORRY and need the explanation dumbed down or a circuit diagram posted to show how the two circuits can be wired together.
It's a tall order.
So Thanks to all who can help me.
Kingsley


image.png image.png
 

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LesJones

Joined Jan 8, 2017
2,417
I think that you could do what you want using quad bilateral switches (CD4066) powered from the 12 volt rail and controlled by the 4017 outputs. The switch in and out pins on the CD4066 could switch in a resistor in parallel with the resistor that sets the longer of the pulse widths so that the combined value gave the required shorter pulse width. (This is on the 555 that controls the servo.) If you did not want to use the CD4066 method you could use a small relay (Driven by a transistor from the 4017 outputs.) to switch the resistors that set the pulse width for the servo.

Les.
 

dannyf

Joined Sep 13, 2015
2,197
I want to control 2 separate RC servos each switched automatically by the traffic light controller 555 / 4017 board (I'll call it the TLC)
that's like trying to control a car with a toaster, :)

if I read you correctly - i'm not confident at all about that, you wanted a motor to be activated based on the state of the lights. if so, it is not that difficult to implement it.

if not, you will need better explanation.
 

Thread Starter

vtolman

Joined Jan 13, 2017
13
that's like trying to control a car with a toaster, :)

if I read you correctly - i'm not confident at all about that, you wanted a motor to be activated based on the state of the lights. if so, it is not that difficult to implement it.

if not, you will need better explanation.
Ok sorry ...
Forget about the car ... That's just telling you what the project will be used for.
I have got the traffic lights sequenced correctly driving the red yellow and green LED's.
I need a circuit diagram to activate two RC servo's (or the servo driver circuit)image.png by the Traffic Light Controller - somehow.
Example ... One LED Light is green and one RC servo rotates to its end travel point for the north south traffic to flow.
And when the other green light turns on a different RC servo will rotate to its end point for the East West traffic to flow.
 

Thread Starter

vtolman

Joined Jan 13, 2017
13
To me the lights are mixed up, Y should be followed by R, R followed by G.
CORRECT The diagram is wrong and I fixed it yesterday - I swap the outputs 3 & 1 wires to the yellow LED's so the Amber lights follow the green.
Not sure why but I redid all all the out puts - easy to do on my bread board.
Starting with 3,2,4,7 are diodes to green then 10 for Amber.
Then 1,5,6,9 are diodes to green then Amber to 11.
The LED's are still in pairs and red's to ground
 
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Thread Starter

vtolman

Joined Jan 13, 2017
13
I actually want the correct functions - ALL red's on at the same time briefly after the yellows but I can't figure a solution yet.
So red's are on for 6 segments, yellows are on for 1 segment, and greens are on for 3 segments.
(No wonder we sit at the lights so long)
Example
outputs 3,2,4 to green, then 7 to Amber and red then 10 somehow outputs to ALL red's only.
Outputs 1,5,6 to green, then 9 to Amber and red, then 11 somehow outputs to all red's only.
But the cross wiring and resisters won't work for ALL reds.
Needs another solution.
 

Bernard

Joined Aug 7, 2008
5,334
Servo & control operate from 6V, LEDs & control could also operate from 6V.
I've shown the long wate solution. Resistor values depend on operating V & LED Vfs.
A close review would be in order.Trafic Light #2 00000.jpg
 

Thread Starter

vtolman

Joined Jan 13, 2017
13
Bernard.
Thanks for the diagram and info.
Please keep in touch as I will try your ideas out and might need more advice as all this is new to me.
I just drew up a new diagram last night to solve the red-red lights issue.
Can it be modified fo do what you advise for the servos ?
It has less diodes and looks a slightly less involved.image.jpeg
 

Thread Starter

vtolman

Joined Jan 13, 2017
13
I think that you could do what you want using quad bilateral switches (CD4066) powered from the 12 volt rail and controlled by the 4017 outputs. The switch in and out pins on the CD4066 could switch in a resistor in parallel with the resistor that sets the longer of the pulse widths so that the combined value gave the required shorter pulse width. (This is on the 555 that controls the servo.) If you did not want to use the CD4066 method you could use a small relay (Driven by a transistor from the 4017 outputs.) to switch the resistors that set the pulse width for the servo.

Les.
Hi Les.
Thanks for the heads up on the cd4066.
I live in Cambodia of all places and it's a month away if I order a 4066.
But if all else fails I will
 

Thread Starter

vtolman

Joined Jan 13, 2017
13
Bernard and Les and others.
Thanks for all your input .... Much appreciated.
Bernard ... Can you or someone please scratch up a rough diagram of wiring the OR gates and diodes to the servo driver switched resistors.
I'm bound to stuff it up ... you can save me all the dramas.
Would the wiring be 4017 outputs go to inputs on the OR gates then the OR outputs go to the diodes then go to the servo driver switches.
I don't get that because the servo driver only needs to be switched (like a relay) not supplied 5v from the OR gate ... What have I missed here ?
........
Unreal .... I bought 6 of the NE555P Timer chips and only one works correctly.
(ID marking is 12AT68M NE555P)
The other 5 are spasmodic causing the sequence of lighting on the controller is unreliable.
Have I bought inferno 555 chips ?
Is that something to look out for ?
Are there more reliable chips (LM555) or could it be something else I've done wrong ?
I have triple checked my circuit and rebuilt it many times with the same results.
I swapped the 555's many times and triple checked the wiring and connections and ONLY ONE 555 chip does the job ... Very Weird.
........
What's more weird is I made the 555 tester circuit (in the photo) and ALL 6 chips indicate the same ... Red LED lights up for a few minutes then changes to the yellow LED which stays on permanently.
The yellow capacitor has 10nJ2A on it .... Correct type or capacitor or not ?
Unfortunately the write up on unitechelectronics.com does not indicate what LED's are to be on or to be flashing to indicate what is good or bad with the 555
...........
The SERVO DRIVER (using the good 555 chip) only holds the servo in one position despite switching between the two resistors.
I can't diagnose the problem yet ? Because I don't know how.
I Triple checked all that wiring and components and rebuilt it twice also.
I have tested all my resistor ohms.
Power to chip and servo is fine.
But I'm not sure if the square yellow capacitors are the correct type needed ?
10nF has 10nJ2A printed on it.
And 100nF has 104J100 (it's Chinese to me)
........
The smaller traffic controller circuit board (in photo) displays exactly the problems with the 555 chips.
.....
Thanks in advance.
Andrew image.pngimage.jpeg
 

Alec_t

Joined Sep 17, 2013
10,592
Looks like on the test board you have R1 = R2 = 39Ω rather than 390Ω (the third colour band seems to be black rather than brown)? If so, the 555 will be straining to supply near maximum rated current. Might account for why some work and others don't.
 

Thread Starter

vtolman

Joined Jan 13, 2017
13
Looks like on the test board you have R1 = R2 = 39Ω rather than 390Ω (the third colour band seems to be black rather than brown)? If so, the 555 will be straining to supply near maximum rated current. Might account for why some work and others don't.
No they are all good I just put the meter on them and colors match 390 390 12k 47k.
Thanks.
 

djsfantasi

Joined Apr 11, 2010
5,833
Your capacitors look like they will run the 555 at greater than 60Hz. At this rate, they will appear to a viewer as always on.
Your circuit calls for a 1μfd capacitor? Yet your text refers to a 100nf. Too small, use the specified value or greater.
 

Bernard

Joined Aug 7, 2008
5,334
Your new circuit looks fine.
Do you have other ICs ? Hopefully a 4001 NOR , or transistors equivalent to 2N3904, NPN, or 2N3906, PNP ?
 

Bernard

Joined Aug 7, 2008
5,334
I think this might work. The servo control as shown is in use on two Pop-Up pistol targets.
The 2k pots can be any low value, 5k-10k.With U1-3 low, adjust R5 for servo in magnets down.
With pin 3 high, adjust R4 for magnets up. No 4001, then we'll make diode NOR if you have a NPN
transistor.Trafic Control 00000.jpg
 

Thread Starter

vtolman

Joined Jan 13, 2017
13
Your capacitors look like they will run the 555 at greater than 60Hz. At this rate, they will appear to a viewer as always on.
Your circuit calls for a 1μfd capacitor? Yet your text refers to a 100nf. Too small, use the specified value or greater.
......
The 555 IC test circuit does have a 50v 1uF (black round cap) and a 10nF (yellow 10nJ2A) as per the circuit.
.......
The servo tester (driver) does have a 100nF (markings 104J100 yellow cap - I hope it's correct) per the per circuit.
And a 10nF (yellow 10nJ2A cap)
 
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