Hello All,
I have a question on a project that I have been thinking about and I don't know where to begin. I am hoping that I can get some suggestions and guidance from you fine folks on here.
My project involves a pinball machine and I would like to build a timing circuit. What I want to do is make a pulsing 50vdc activate and continuously run a pair of mars rotating beacons. I want the beacons to run until the pulsing voltage stops and then the beacons can stop.
Here's the setup. I have a shaker motor that runs on 50vdc and the logic pulses the voltage to the motor to vary the intensity of the shaking. I want to hook up the lights and use the pulsing voltage as a trigger to turn on the beacons.
Any ideas on a what kind of circuit to build? I have been looking at a 555 timer running as a retriggerable monostable circuit, but the voltages don't look right. Maybe I just don't understand as much as I should. Any help would be greatly appreciated. Thanks!!!

 

What are "mars rotating beacons" and why do they need pulses to work? Please provide more info.

 

Mars rotating beacons are lights that flash by having a reflector spin by the lamp. Like what's on top of police cars before they started using the L.E.D.'s. The reason why I wanted to use the pulsing is because when the machine activates the shaker motor is when I want the lights to come on. Nothing else on the machine turns on solely when the shaker motor is running or else I would use that, instead, to turn on my lights. If I just hook it up directly to the pulsing 50vdc, the lights would just switch on and off. I want it to be steady on while the shaker motor is being pulsed by the logic.

 

Can you measure the frequency and duty cycle
of the pulses?

 

Sorry Pencil, could you elaborate? I don't know exactly how to do that, but if you can give me and idea, I would try.

Also, I just got some more information. The game apparently controls the GROUND to the motor. So the pulsing is actually created by the game increasing the voltage to the motor from around 38vdc to close to 50vdc. It starts out with the higher voltage, then gets lower to make the motor run slower, then increases the voltage again when it wants to intensify the shaking by speeding up the motor.

So knowing this, what I can do is run a dedicated power supply to the lights, but then run the ground to the shaker motor!! I think this project just got easier!!

 

I'm thinking one way would be to "tap into"
the source of the trigger for the shaker. Something has
to trigger the circuitry that causes the motor to start
or change speeds. You would probably have to do some
tracing/testing starting from the motor, back to a PCB
then following the traces back to an I.C. and finally
testing each pin for a signal (may be V+ or ground).
Of course there is some risk involved with poking around
an unknown circuit.

Also, I just got some more information. The game apparently controls the GROUND to the motor.....
So knowing this, what I can do is run a dedicated power supply to the lights, but then run the ground to the shaker motor!!

If this is true.

There may be a relay in there somewhere. Get your signal
from there to trigger another relay for your lights.


Depending on how you are measuring the voltage at the motor,
the voltage may not be varying. Your meter may be showing
the "average or apparent" (term?) voltage based on a varying duty
cycle (change of pulses) of the output.

 

When I measure the voltage going to the motor when it turns on, i get 24Vdc-38vdc. It bounces around between the two. I was thinking of creating a board with a voltage regulator on it. Take the power AT the motor, run it through the regulator (LM317 or 7824) to lower the voltage then run that lower voltage through a relay to switch it on. The other side of the relay would be the power or ground wire of the light, which has it's own power supply. Do you think this is feasible enough?

 

I do not seem to find any specs on beacon motor or light

 

@Bernard
Motor in this case is the shaker motor in the cabinet of the Williams manufactured pinball machine titled, "Earthshaker"

 

Hello All,
So sorry for reviving an old thread. I have been sidelined with family problems and was unable to get back to the project until now. But all in all, I finally have an update and maybe you fine folks could help me again.
Ok, my shaker motor is triggered from the logic through a Tip122 transistor.

 

This in turn goes to the base of a Tip36c tranistor which turn on the motor. The tip36c is on a high current driver board right before the motor. So, 40 vdc from an aux power board goes to the high current board to power the motor. The signal from the logic (BLU-BLK wire) grounds the base of the Tip36c and turns on motor. What confuses me is that there is 40vdc on this BLU-BLK wire as well. (I have attached the schematic of the high current driver board on previous post.)
Here is my question: I built another High current driver board with the same specs. The difference is that instead of having 40vdc to it, I am only driving 12vdc through it. I am using the same signal wire (BLU-BLK) to trigger the Tip36c for my lights. Problems is that as soon as signal wire touches other signal wire, shaker motor turns on! Any ideas or suggestions are greatly appreciated!

 

Please post a schematic showing the TIP 122, TIP36c,
VCC and GND of both (12v and 40v) power supplies, and
the board you have made.

What confuses me is that there is 40vdc on this BLU-BLK wire as well.

Disconnect the motor then recheck the BLU-BLK wire.

 

Horrible picture, but I got it to work.

My guess would be

RED-WHT is the 50V supply
BLK is return or ground
BLU-BLK will go to ground when the shaker motor is to turn on. It then may be either open circuit or 50V, can't tell from the limited info.

The emitter of Q1 should be bouncing between 50V (when shaker off) and ground (when it's on) during your event. That may be your trigger signal.

To convert some pulses to a steady signal you'll need something called a "retriggerable monostable." These have a defined output width you'll set a little longer then the shake pulse, and then they retrigger on the next pulse. As long as pulses are hitting it it stays on, and once the pulses cease it times out and goes off.

I don't believe a '555 can work this way, but there are several CMOS and TTL chips that do. You have to convert the input pulses for the logic level, then you convert the output to something to drive the Mars light, like a relay or a transistor.

Sorry, but not knowing what the pulses are I can't comment on a specific input level converter.

(And there isn't a problem waking your own thread: you already own it.)

 

Please post a schematic showing the TIP 122, TIP36c,
VCC and GND of both (12v and 40v) power supplies, and
the board you have made.

@Pencil: The pic I attached is the schematic for the board I made. I am attaching the link to the manual as well as pages that they are on, just in case my pic don't come out right. Q79 is the driver transistor and it has a "pre" driver transistor before it.
Tip 120 transistor labeled as Q79 is on page 82 of pdf file and pages 95 & 96 are the Aux power driver board where the 25vdc comes from that goes to the high current driver board that is right before the shaker motor. Haven't looked at power while motor is unplugged yet, will do later tonight.

 

@ErnieM: Thanks for the 555 circuit suggestion. I was looking into something in that area before but saw something else that seemed more promising. The other thing I was thinking as well is just using a piezo buzzer as a vibration trigger to connect the 12v to ground, so that when the motor turns on, it triggers the buzzer ... thus connecting the ground and turning on the lights!

 

I have a question, will this circuit work? I mean do I have to worry about something blowing up on here? What I am doing is the 24v source is constant. The switch on the ground side represents the pinball pulsing the ground. Now in this simulation, the pulsing of the ground will cause the relay to stay closed until the pulsing stops. I am planning on using this to run my lights. Is there anything else I am missing on this circuit? Your advice would be greatly appreciated.

 

I have a question, will this circuit work? I mean do I have to worry about something blowing up on here? What I am doing is the 24v source is constant. The switch on the ground side represents the pinball pulsing the ground. Now in this simulation, the pulsing of the ground will cause the relay to stay closed until the pulsing stops. I am planning on using this to run my lights. Is there anything else I am missing on this circuit? Your advice would be greatly appreciated.

It's a nice idea but it's not a very practicable way to keep the relay on. The relay needs a lot of current which means you need a huge cap to supply it,

 

But will it work? I mean I have a 470uF cap for the project. Just not sure about the math.