Solenoid rapid on / off circuit for arcade game gun recoil

Thread Starter

Goemon

Joined Nov 6, 2018
7
I was hoping that someone here could point me in the right direction for this project...

I am building a home arcade cabinet set-up to use with my light gun games and I want to add a recoil solenoid.

My 12v (nominal) solenoid is currently wired to a micro switch so it activates once when the switch is pressed. I want to make it so it rapidly cycles on and off approximately 12 times per second when I hold the micro switch. I was hoping that someone here can tell me the simplest method of achieving this?

In case it isn't obvious, I'm new to electronics projects like this. I don't have any programing skills and I don't know what all the symbols mean on other people's circuit diagrams. But.... I can follow simple (and specific) instructions and I can solder.
 

Alec_t

Joined Sep 17, 2013
10,924
Solenoids have a property called 'inductance' which opposes rapid changes in current. This, together with mechanical inertia, makes it difficult to get them to pull in and release rapidly so, as per post#2 and depending on the solenoid's characteristics, you may not get as rapid an operation rate as you are hoping for.
 

Thread Starter

Goemon

Joined Nov 6, 2018
7
We don't need to focus on the capabilities of the solenoid. I have a whole box full of them so i will choose the one I need for the job.

It's everything else I need help with - i.e. Creating a circuit that can rapidly turn on and off a 12v or 24v current.

On the mechanics and properties of solenoids, I am not looking to break new ground. Solenoids have been used for exactly this purpose and at that sort of speed in arcade guns for decades.

If it helps to see an example, here is one of the solenoids used for recoil in the Terminator Salvation cabinet - a game that has full auto recoil:

https://www.betsonparts.com/solenoid-for-raw-thrills-terminator-42-deluxe-gun.html

Here is another example:

https://www.betsonparts.com/time-crisis-4-gun-solenoid-iv.html

Here is a video of one of my solenoids running at the sort of speed I am looking for, using a very crude design that has the solenoid immediately breaking the circuit as soon as it is activated:


So... if I could create a circuit to do the same thing reliably (and safely), that would fit my needs. I just don't know how to do that. Everyone else's recoil circuits seem to have half a dozen (or more) components and they operate at consistent speeds without sparks flying everywhere...
 

Danko

Joined Nov 22, 2017
875
Is the supply AC? I had been assuming DC supply, but I don't see any indication either way in the previous post
Also, shouldn't there be a flyback (or freewheeling) diode across L1?
AC power supply V1 (it may be simple transformer) is part of circuit, and any other PS are not required.
Diode D4 is rectifier and flyback diode also.
Self induction current goes across M1, V1 and D4.
By this way energy, accumulated in coil, not dissipates,
but returns to power supply.
M1 not dissipates energy in transition processes,
because M1 is shorted before drain voltage appears
and opened after drain current becomes zero.
It is big advantage of synchronous work with AC derived pulses.
 
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Danko

Joined Nov 22, 2017
875
@crutschow, "Fly back" means "return something to starting position".
Definition of flyback in English by Oxford Dictionaries:
"The return of the scanning spot in a cathode ray tube to the starting point."
So diode, which helps to return scanning spot, called "flyback diode".
Energy, accumulated in coil, "flying back" to power supply through diode D4.
Therefore D4 is "flyback diode".
 
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crutschow

Joined Mar 14, 2008
24,410
Therefore D4 is "flyback diode".
D4 does not return the inductor energy to the power supply so it definitely is not a "flyback diode".
Don't know why you think it does.
D1 can only pull energy out of the supply. It would have to be in the opposite direction to return energy.

And it certainly doesn't protect the MOSFET from the transient.
 

ebeowulf17

Joined Aug 12, 2014
3,184
D4 does not return the inductor energy to the power supply so it definitely is not a "flyback diode".
Don't know why you think it does.
D1 can only pull energy out of the supply. It would have to be in the opposite direction to return energy.

And it certainly doesn't protect the MOSFET from the transient.
It looks like the circuit is designed such that switching always happens at zero volts or zero current so there shouldn't be any transient across the MOSFET, maybe? I'm not at all confident that I understand the circuit - I'm just going by the simulation results.

Regardless, I don't see how D4 is a flyback diode, only a rectifier it seems. I'm totally with you on that one.

I suppose the question that remains is, if you design a circuit that should never generate an inductive transient, do you still need the flyback diode for edge cases, like the whole circuit losing power while the coil is active?
 

crutschow

Joined Mar 14, 2008
24,410
if you design a circuit that should never generate an inductive transient, do you still need the flyback diode for edge cases, like the whole circuit losing power while the coil is active?
I would, because there's always the pathological event that can cause a transient, and it only takes one to zap the MOSFET. :eek:
 

Danko

Joined Nov 22, 2017
875
D4 does not return the inductor energy to the power supply so it definitely is not a "flyback diode".
Don't know why you think it does.
Well, pay attention to phase shift between AC voltage and coil current.
Maximum current Imax is in moment, when AC voltage crossed zero.
Thereafter direction of current becomes opposite to current,
which should be flowing from AC source.
From this moment coil energy is "flying" from coil to power supply,
and current fade out.
So D4 is definitely "flyback diode".
D1 can only pull energy out of the supply. It would have to be in the opposite direction to return energy.
Yes, coil voltage changes its polarity in moment Imax.
else how D4 still conductive from Imax to I=0, when AC polarity is blocking for D4?
And it certainly doesn't protect the MOSFET from the transient.
Transient processes are unusual for this circuit, but just to be on the safe side,
I added protection diode D5 :) in parallel with L1, and replaced picture in post #9.
 

dendad

Joined Feb 20, 2016
3,332
That video does not appear to have a diode across the coil, just look at the spark.
A diode across the coil will slow it down as the diode keeps the coil current flowing for a bit after the power is removed.
Test the coils like in the video, as a buzzer, and try with and without diodes.
You may be able to use a motor with an offset weight instead of a solenoid.
 

Danko

Joined Nov 22, 2017
875
A diode across the coil will slow it down as the diode keeps the coil current flowing for a bit after the power is removed
dendad, you are right!
see on the picture below - energy in coil continuously rises, coil dynamical de-energizing not works because coil not able increase voltage for drop energy to power supply through diode D4.
EDIT:
So, this circuit is very good for fast working electromagnets, but it must work without protection (protect from what?) diode, in principle.
Maybe best solution for this circuit is put 50V zener diode between drain and source...
Pulse_L.PNG
 
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MisterBill2

Joined Jan 23, 2018
5,252
A simpler arrangement will be to have the solenoid operate a switch when it approaches full stroke, and then have that switch drive the circuit to release the solenoid. That way it will only try to move as fast as it can, and the cycles will thend to slow a bit as the solenoid heats up. The function is very similar to an electromechanical buzzer. I built one of these back in 1956, and it worked very well.

Additional facts: The solenoid was powered by the 110 volt 60Hz mains, the contacts were broken when the armature was about 75% of full stroke, inertia carried it hard into the stop at which point he mostly compressed return spring started the return stroke. The contact closed at about 20% of the return stroke remaining and so the armature did not hit the return stop very hard, but was already being pulled forward. The thing was very noisy, which was the intent, and it really hammered away. The coil was rated at 110 volts and constant duty cycle, and drew nearly an amp when fully engaged, which was not how I was using it.
 
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