Author Topic: Need help with T2 solenoid driver circuit! (Read 7738 times)

1UP · « **on:** March 26, 2002, 01:05:39 am »

OK, I'm finally going to get my Terminator 2 guns up and running. As we know, the T2 gun has a solenoid or pinball coil driving a metal piston which causes a recoil feedback when firing the gun.

I'm trying to build a circuit from scratch which will interface the Ipac LED harness to drive the 24V power supply I've connected to the solenoid. Dave Widel already has a software hack that sends the recoil and LED signals from the game to the CAPS/NUM/Scroll Lock LEDs on the keyboard (or Ipac LED harness).

The hardware part is done by using the recoil signal (5v) to switch a high-voltage power transistor, thus turning on and off the 24v power supply to the coil.

So far, the circuit has only been tested by driving a brighter LED, (since I don't want to risk frying my Ipac with 24V until I know what I'm doing) but it seems to work! The question is, if my transistor can take a 5V, 2A current at the base, do I need any kind of resistor to protect the transistor from the Ipac current (5V @ 10ma) or vice versa? Are there any problems with my circuit that strike you? Any other suggestions?

Thanks

Ron Michallick · « **Reply #1 on:** March 26, 2002, 06:09:02 am »

The only reason the LED lights is the R1 to transistor
base-emitter diode. There is no gain and the caps are
blocking not filtering the recified AC. With luck the caps
may not explode, but it'll never drive the coil.

Doom and gloom aside, send me an email and I'll send
you an alternate circuit.

Ron.

ErikRuud · « **Reply #2 on:** March 26, 2002, 06:41:15 am »

Whatever circuit you use, make sure you protect against "Back EMF".

A solenoid is an electro magnetic coil. When you put power through it, you get a magnetic field. When you turn the power off, the magnetic field collapses. The collapsing magneic field passes through the wire in the solenoid, it actually generates a small amount of current. The polarity of this current is reversed. So you get a small pulse of power running backwards through your circuit. This could harm your IPac.

You need to isloate the coil from the IPac. One way is to use a small diode to block the reverse flow.

Carsten Carlos · « **Reply #3 on:** March 26, 2002, 09:12:52 am »

Yep, don't forget the diode mentioned before - but not TO small

If you have to use a 24V-power anyway, why not use a relay (don't know if there are any 10mA relays out there, but electronics get better, so why not?)?
So you don't even need to hook up the 24V-ground with your PC-ground!

ErikRuud · « **Reply #4 on:** March 26, 2002, 09:34:02 am »

Yes, a relay wood be good. You can eve get solid state ones that do not click. That way you would isolate the 24 volts from your IPac, and your motherboard.

However, a regular relay is also an electromagnetic device, so yo will still need a diode to block the back EMF.

As a side note, we actually make use of back EMF in slot car racing to create dynamic braking when we release the trigger on the controllers.

Beley · « **Reply #5 on:** March 26, 2002, 11:37:21 am »

This is the circuit i would probably use

1UP · « **Reply #6 on:** March 26, 2002, 12:05:20 pm »

The relay sounds like a good idea. I've always been worried about grounding the two together. So, the diode would be used to absorb the relay's back EMF current spike?

What do you all think of Beley's circuit above?

ErikRuud · « **Reply #7 on:** March 26, 2002, 12:19:11 pm »

The above circuit looks better than the first. It has the diodes to block the back emf.

But using a relay, solid state relay, or an opto-isolator chip would be even better. The opto-isolator might be overkill and would complicate the circuit, but it would provide the best protection. I think they were discussed in another thread.

1UP · « **Reply #8 on:** March 26, 2002, 01:00:21 pm »

Quote

The above circuit looks better than the first.

1UP · « **Reply #9 on:** March 26, 2002, 06:29:50 pm »

Hey, WTF does the abbreviation VA mean in electronics terms? (I have a relay rated at 10VA)

Thenasty · « **Reply #10 on:** March 26, 2002, 06:59:39 pm »

Quote

Hey, WTF does the abbreviation VA mean in electronics terms?

1UP · « **Reply #11 on:** March 26, 2002, 07:04:30 pm »

Quote

I think its Volt Ampere

...OK, what does this mean to me?

1UP · « **Reply #12 on:** March 26, 2002, 07:11:38 pm »

Would this work?

BTW, there's a diode on the gun coil shorted across the two coil leads. Not sure what this does, but do I still need a diode AFTER the coil (before the relay)?

ErikRuud · « **Reply #13 on:** March 26, 2002, 08:29:51 pm »

Un-regulated power supplies are often often rated in VA. The fact that they are un-regulated means that if the current demand goes up, the voltage may go down as the power supply tries meet the demand.

I can find a link to more technical explanation if you want.

1UP · « **Reply #14 on:** March 26, 2002, 08:51:43 pm »

OK, did some tinkering, here's what I came up with.

I could only find a solid-state relay that switched AC current using 5VDC.

Beley · « **Reply #15 on:** March 26, 2002, 10:49:15 pm »

Quote

I could only find a solid-state relay that switched AC current using 5VDC.

1UP · « **Reply #16 on:** March 26, 2002, 11:25:21 pm »

Dammit, I went out and got a 1uF cap when I already had a 1000uF!

ErikRuud · « **Reply #17 on:** March 27, 2002, 05:56:24 am »

If you are using a solid state relay, you shouldn't need the diode. There is no coil in a solid state relay, so there would be no back EMF.

Elkor · « **Reply #18 on:** March 27, 2002, 06:42:47 am »

While I have done some extensive (if simplistic) electronics in the past, and understand what you want to do, wouldn't it just be a lot more simple to have the relay fire when the trigger is depressed and not worry about the ipac led's at all? then it could be done with a simple relay or even a transistor to fire the solenoid?

Does mame even flash the led's for the gun fire or would there be a source code change as well (I have not looked myself)?

I dunno, just seems easier to make it an independent function (especially as it is specialized equipment (T2 guns) anyway).

-C

Dav · « **Reply #19 on:** March 27, 2002, 06:52:55 am »

Looks like you're making good progress

. If you need any info from the original coil driver board like schematics or transistor part numbers let me know. I'm hoping to do another small run of pcbs in ~4-6 weeks if you get something working well I'll run off a few and send you one.

Dave

1UP · « **Reply #20 on:** March 27, 2002, 09:52:21 am »

Quote

While I have done some extensive (if simplistic) electronics in the past, and understand what you want to do, wouldn't it just be a lot more simple to have the relay fire when the trigger is depressed and not worry about the ipac led's at all?

Elkor · « **Reply #21 on:** March 27, 2002, 11:42:48 am »

Well then.

<- put in place.

I guess that answers that!

(for the record, I did not now that the guns slowed down and was working on the assumtion of a constant rate of fire. That's what I get for guessing)

The good news is: your circuit looks like it will work just fine, I would drive the DC circuit instead of the AC one for exactly the reasons listed, hook the DC leads up just like you have in reply #12. Not quite sure what voltage andy is driving the led on the ipac with but 5V seems reasonable and it is easy enough to check, just use a multimeter on the lead before the series resistor (or ask him). Your ipac shoud be fine. The diode won't hurt, you just don't need it w/a solid state relay.

And, yes, solenoids do wear out. (i.e. pinball flippers)

Bill Lash · « **Reply #22 on:** March 27, 2002, 11:52:55 am »

I just started looking at this thread, and I think you guys are putting your back EMF diodes in the wrong place. I have always seen them in parallel with the coil.

When you turn off the transistor, the current will continue to flow through the coil, building up voltage. If you put
a diode across the coil, that is reverse biased when you turn on the transistor (so no current flows through it), when you turn off the transistor, the current will flow through the diode until it dies out.

You may want to look at http://www.jaycar.com.au/PDFS/relaydrv.pdf

Beley · « **Reply #23 on:** March 27, 2002, 12:15:13 pm »

Quote

Dammit, I went out and got a 1uF cap when I already had a 1000uF!

Elkor · « **Reply #24 on:** March 27, 2002, 12:33:46 pm »

Quote

I just started looking at this thread, and I think you guys are putting your back EMF diodes in the wrong place.

1UP · « **Reply #25 on:** March 27, 2002, 01:22:58 pm »

Quote

I just started looking at this thread, and I think you guys are putting your back EMF diodes in the wrong place.

ErikRuud · « **Reply #26 on:** March 27, 2002, 01:33:19 pm »

Here, I will post the link here as well.

Weeder Technologies

When I originally found the Weeder Site, he had an option to buy the boards as a kit. He seems to have dropped that option.

Elkor · « **Reply #27 on:** March 28, 2002, 05:38:24 am »

Well? did you get it working? don't leave us all in suspense!

1UP · « **Reply #28 on:** March 29, 2002, 01:04:20 am »

Sorry for the wait, I've been sick!

Dav · « **Reply #29 on:** March 29, 2002, 04:48:59 pm »

Good job. I don't know anything about the IPAC but generaly if you're too high on the current the resistance in your load is too low, it acts like a short circuit. So it can't be good for it. I wouldn't worry about the relay. I assume he was conservative in his maximum but you're way over. Driver boards usually have a small transitor first then the large transistor so they step up gradually in current draw.

I haven't done anything with the parallel port yet, I've been busy writing Z80 code and manufacturing circuit boards for my Ms Pacman project. I might see if I can find the source for it though. Maybe someone who's worked with parallel ports before will work on it. It may not be that difficult, but I haven't hooked up an led to my port yet so I can test.

Dave

1UP · « **Reply #30 on:** March 31, 2002, 05:07:08 pm »

Hey Dave, do you at least have the source for the T2 keyboard LED hack so I can recompile it with the latest Mame? I can't get the old DMame hack to work with XP! That way I'd have at least one gun working.

Is there any way I could use a transformer or some other method to step my Ipac's 5V control signal down to the 1.2V that the relay wants, while raising the Ipac's ouput current from 10ma to the 20-50ma for switching?

Dav · « **Reply #31 on:** April 02, 2002, 08:52:05 am »

Send me an email and I'll send it.

The Ipac current will raise automatically and attempt to put out 50 ma, that is the problem. I'm sure you could use a small transistor, but i don't know a enough about transistors to tell you which one. I don't mess them much. Maybe one of the electronics gurus can help.

I know a little more about digital components. You could hook up a 4066 switch. It works like a relay. You put in 5v and it closes the switch, you could use it to ground your relay. I don't know how much current it handels but it's a quad switch, you could use all 4. The big advantage would be it would isolate your ipac from damage. But you'd need to check how much current it puts out and draws.

Dave

Beley · « **Reply #32 on:** April 02, 2002, 11:25:13 am »

Quote

Is there any way I could use a transformer or some other method to step my Ipac's 5V control signal down to the 1.2V that the relay wants, while raising the Ipac's ouput current from 10ma to the 20-50ma for switching?

A transformer wouldnt work, they only work for AC, like Dav said you could try using a 4066 but it might not handel the current. An easer (and better solution IMO) is to use an opto-isolator, which is just as easy to hook up and would protect your Ipac from almost anything. I would recoment using something like a 4N33. connect the LED outputs to pin1 and 2, and connect the relay to pin 5 and +1.2 and collect pin 4 to ground.

1UP · « **Reply #33 on:** April 02, 2002, 11:25:22 pm »

Good to see this topic is still alive! I'm kind of at a standstill until I have a good finished design and the proper software to drive it. But I'm absolutely not going to finish my cab until I get this working!!

ErikRuud · « **Reply #34 on:** April 04, 2002, 06:29:18 am »

1Up,

Here is an idea for you to think about.

Use one of the Weeder boards, or some homebrew cicuit, to control a motor. This motor would rotate your control panel for you.

The same thing could be done for rotating monitors.

Just some food for thoufght.

1UP · « **Reply #35 on:** April 04, 2002, 04:47:05 pm »

Quote

1Up,

Here is an idea for you to think about.

Use one of the Weeder boards, or some homebrew cicuit, to control a motor.

SirPoonga · « **Reply #36 on:** April 05, 2002, 12:59:33 am »

This falls along the same lines as my qbert knocker which is just a solenoid. I think I might end up buying that serial port relays.

Hey, one relay for qbert, one relay for t2...

Dav · « **Reply #37 on:** April 05, 2002, 04:22:42 am »

Quote

This falls along the same lines as my qbert knocker which is just a solenoid.

SeaMonkey · « **Reply #38 on:** December 07, 2004, 04:37:48 pm »

The feedback is such a great idea I hope this gets a walk-through when you guys get it working. I will probably make a dedicated cab for positional shooters when this gets nailed down.

SeaMonkey · « **Reply #39 on:** December 08, 2004, 03:37:50 pm »

Here is the actual control board for that gun.

Would that be in any way helpful?

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=13718&item=6137139280&rd=1


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Author Topic: Need help with T2 solenoid driver circuit! (Read 7738 times)

Ron Michallick

Bill Lash