How hot do your solenoids get? With Video

[charlieram]

A question for anyone with gun recoil solenoids fitted, how hot do yours get?
The reason I ask is because I have made a recoil circuit to take the signals from mamehooker and activate the solenoids. they are the standard solenoids from ultimarc with my circuit and a 24v 5amp psu.
I started setting the guns up with the various emulators the other day but after about ten minutes of playing T2 and operation wolf withe the automatic recoils I noticed that the gun shell was quite hot, not burning hot but hotter than warm if you know what i mean
Do your guns get warmand should i be worried? Im no electronics expert but my circuit does at least work but if anyone would like to take a look and advise some changes i could make then I would be hugely greatful. Its over in the automated projects section.
Please help me!

[charlieram]

No one? 

[BadMouth]

Relatively few people are using solenoids and of those who are, I'd guess that nearly all of them are using the Aim-Trak firmware to trigger them instead of MAMEhooker.  So their solenoids aren't getting the workout yours are.

The feedback on the positional gun that I use is a vibration motor hooked up to the trigger, so it isn't comparable.

[charlieram]

Cheers  for replying, I know a lot of people will be using stock firmware but, if they could stand there repeatedly pulling the trigger as fast as they can for ten minutes and then check the temperature they would be doing some great research Seriously though, I was hoping some people out their would have recoil guns and would have noticed whether they got hot.

[WindDrake]

What's the resistance across the coil? 5 Amps/24v means they are using something like a 6ohm coil. This means you are dumping something like 100-120 watts of power dissipated every time you hit the trigger. If MAME Hooker is keeping the drive to the transistor held down too long, you are going to dump power into the coil without generating any effect, and bleeding that power off as heat.

I'd try shedding some drive time, maybe cut a third of it out and go from there.

[WindDrake]

Just thought of something else.

How are you triggering the coil?

First thing that comes to mind is using a P-Channel Enh. FET and using an active-low signal to trigger it, with something 4.7k or so as a Pullup resistor to the rail.

There is a possibility that you've got a transistor that isn't turning all the way off. Coils, like any inductor, are going to try to resist changes in voltage, so I can't see a pulse width being a problem unless it's super, super long.

I'd check and see if you've got a leak. Either a partially biased fet, or a leaking anti-ringing cap, or even a bad flyback diode.

[charlieram]

See, its stuff like that I just dont know, Well over my head. mame hooker is sending an 18ms pulse to the coil, well that is  what i can ask it to do minimum, any less than that and it doesnt activate consistently. I have no way of checking how long the voltage is supplied to yh coil or whether it is on/off or rising and falling. this is why i would like advice one my circuit. DaOldman has been really helpful but he doesnt have recoil  guns.

[Fursphere]

So..  I've had solenoid pump black smoke out of my pinball machines.  If I wasn't present I'm curious if it would have caught fire.

[lilshawn]

I have no way of checking how long the voltage is supplied to yh coil or whether it is on/off or rising and falling.

fire off your solenoid a few times... use voltmeter to check your + and - on the solenoid after. if there is a residual voltage left flowing after it's been fired off, your FET isn't turning off all the way causing a tiny flow. you may need to use a pull down resistor on the FET to get it to shut all the way off.

you may find when you fire it off a couple dozen times the voltage is going to build up and up and up and stay for longer until it bleeds off naturally through the coil. (could be several seconds) that would be where your heat is coming from.

but, if it dumps right back to zero, it's not bleeding voltage.. you may just need to shorten your pulse length.

ideally you want the pulse to be just as long as it takes for the solenoid to go from it's normal resting state to fully retracted. if it takes 8 MS to do that, there would be no sense driving it any longer than that. It's pretty difficult to measure that, I only mention it because it pertains to this situation.

So..  I've had solenoid pump black smoke out of my pinball machines.  If I wasn't present I'm curious if it would have caught fire.

a stock system, no. It will melt and smell nasty but it shouldn't catch fire.

on a rigged system (IE over fused) yes, it's very much a possibility. not to mention you risk burning a hole clean through your driver board as the FET burns up and takes out ALL your wiring with it.

lesson kids: if it says 3 amp fuse. IT'S A 3 AMP FUSE ONLY! not a 4 amp, not a 10 amp, not a 30 amp, and ESPECIALLY not tinfoil. 

[charlieram]

I have no way of checking how long the voltage is supplied to yh coil or whether it is on/off or rising and falling.

fire off your solenoid a few times... use voltmeter to check your + and - on the solenoid after.

I had actually tried that but my voltmeter isn't very responsive, It is a digital one I bought years ago for some project and then I didn't use it for years. It takes too long for it to register voltage before the solenoid has fired and then gone back to rest. If I use the fully automatic gun on T2 it catches the high voltage eventually but not the low. I also checked the voltage across the coils when no output is required and that seems OK (0v)
My circuit is below

[lilshawn]

i'm wondering if those snubber diodes are enough... the 1n4001 is only 35 volts RMS reverse voltage. don't forget you are going to have a huge surge of voltage (100's of volts for a few microseconds) from the solenoid as the magnetic field collapses. but, without an o'scope, it would be difficult to see what's really going on.

if you have access to some 1N4004's or higher, maybe give them a try. I would consider a 4004 the bare minimum for a solenoid which is what i use when replacing them in pinballs. (280 volts RMS reverse) it can't hurt things in your circuit. it's just for that spike from the solenoid when the magnetic field collapses.

other than that, the circuit looks good to me.

Perhaps there is a big droop in the power supply when the solenoid fires that is screwing things up. Your power supply may not be pushing the voltage back up to 24 volts quickly enough. a linear power supply doesn't have much of this issue, but a switchmode supply needs a large power cap on the output  (6000 or 10,000uF) to smooth out that big power sag.

[ed12]

yes jump up to 4004's for the diodes..
but i see no snubber in the fet circuit ?
.1/100v is nessary to stop hyestera..
18ms is rather long for and coil,that is rapit fire

ed

[charlieram]

yes jump up to 4004's for the diodes..

but i see no snubber in the fet circuit ?
.1/100v is nessary to stop hyestera..

Do you mean a diode across the 4.7K resistor? I'm not sure what you mean

18ms is rather long for and coil,that is rapit fire

18ms is the smallest value I can use in mame hooker otherwise the coil doesn't fire and Andy's firmware for the aimtraks fires up to 50ms if I understand it correctly

[Fursphere]

So..  I've had solenoid pump black smoke out of my pinball machines.  If I wasn't present I'm curious if it would have caught fire.

a stock system, no. It will melt and smell nasty but it shouldn't catch fire.

on a rigged system (IE over fused) yes, it's very much a possibility. not to mention you risk burning a hole clean through your driver board as the FET burns up and takes out ALL your wiring with it.

lesson kids: if it says 3 amp fuse. IT'S A 3 AMP FUSE ONLY! not a 4 amp, not a 10 amp, not a 30 amp, and ESPECIALLY not tinfoil. 

It wasn't over fused.  It was a failed transistor on the driver board - aftermarket Ni Wumpf CPU and Driver board in a Gottlieb sys80 Black Hole.  The knocker coil just went up and lightly burned the inside of the cabinet. 

Stock fused in all locations.  Ground mods done.  It just happens sometimes. 

[charlieram]

I posted this in the Automated projects forum but it is also relevant to this post..
Maybe a video will explain things a bit better
This is the recoil action controlled by Mame Hooker using the outputs broadcast by mame when playing Terminator 2, using this method means that when the energy runs low, the solenoid pulses slow down too and for other games with the outputs hooked up it will also stop firing if you run out of ammo and need to reload.
Don't mind the 2 gun sights, I havn't properly calibrated yet and wont do until its all back in my cabinet. The 'clacking' you can hear is the solenoid firing, After playing this game for about 10-15 minutes the gun feels warm where the solenoid is located. I took the gun case apart to check the temperature of the solenoid and while I can hold it it is uncomfortably hot. Would you say it is down to the rate of fire or something in my circuit?

[WindDrake]

I'd say bring the snubber diodes up to 1N4004's and try again. Your diodes may not be dissipating the collapse currents fast enough, forcing the coils to bleed it off.

You can also try using a 1 Watt Flameproof 100k resistor across the FET (Source>Drain) to see if you can pull more garbage off the line.

This kind of thing is actually really hard to diagnose without a scope, you get into Black Magic territory.

[Marton]

Are they still running hot? Any problems with the coils?? I'm about to do the same on a Revolution X cabinet