Power supply config for Ultimarc Dual Aimtraks with recoil

[arcaderX]

Hi all

I'm hoping you guys might be able to help me understand my setup better in the quest for optimum performance.

I recently purchased my arcade cabinet and ticked the box that says: "Dual Aimtrak with recoil" 

It was delivered all setup with a USB hub (4 port) and DC power sockets (x2) on the front of the cabinet to connect the guns.  The guns all work as does the recoil.  I'm just trying to get them all setup with MAME and HOTD etc.  Getting there (I think).

I looked inside the cabinet and there is a single PSU for the Aimtraks rated at 36V / 3A.

A single DC cable comes from the PSU and has been split open to reveal a red and white wire.  These two wires have been fed into separate sections on one side of a terminal block.  Two wires (red/black) have been connected to the other side of the terminal block, i.e., 1 red/black wire connected facing the original red wire and another facing the original white wire.  Each red/black wire is then connected to the back of the DC socket on the front of the cabinet.  As shown below:


(ignore the other red/black wire shown in the photo, that is fed from elsewhere and connects to the power button on the front of the cabinet to turn it all on)

• Firstly, is that wiring legit? I am no electrician  but I'm just not sure if each independent DC socket can be powered from 1 cable from the original PSU like that.  As I say, it does all work!
• Secondly, I thought that two guns would mean you would need two separate PSUs, i.e., both 36V /3A, one for each?
• Would I get better performance from two separate PSUs (i.e., better recoil)?
• Finally, I actually want to keep the guns connected all of the time so want to have them connected directly to my PC and route the cables around the back, so I will probably get two USB extension tables and maybe some additional DC sockets and two DC extension cables.  Any thoughts on what I would need?

Thanks in advance for your thoughts on any of these points.

[lilshawn]

• Firstly, is that wiring legit? I am no electrician  but I'm just not sure if each independent DC socket can be powered from 1 cable from the original PSU like that.  As I say, it does all work!
• Secondly, I thought that two guns would mean you would need two separate PSUs, i.e., both 36V /3A, one for each?
• Would I get better performance from two separate PSUs (i.e., better recoil)?
• Finally, I actually want to keep the guns connected all of the time so want to have them connected directly to my PC and route the cables around the back, so I will probably get two USB extension tables and maybe some additional DC sockets and two DC extension cables.  Any thoughts on what I would need?

1: you stated "A single DC cable comes from the PSU and has been split open to reveal a red and white wire." would this not be 2 wires then? just because it has a plastic cover on the outside and appears as a single cable, it may in fact have 2,3,4,310 wires inside it. you have 2 wires... a positive and a negative. this is what your red/black barrel connections are using.

2: the aimtrak power requirement is really only about 2 amps (it's recommended 4 but that's neither here nor there). sharing the power between 2 guns at a point when they both have to trigger simultaneously might result in a slight decrease in the motion felt on both guns.

3: it's possible. if the perceived motion of the gun is considerably different than when fired independently, then sure go ahead and use a larger supply, or like you mentioned, 2 separate supplies.

4: I would advise against powering the guns from the computer's power supply, the noise and ripple introduced by the firing can cause havoc on a running computer causing all kinds of crashing, lockups, or even corrupted data. a solenoid coil is a very dirty thing to operate and without proper suppression, the back EMP from the coil magnetic field collapsing... it can cause dips and surges in the power supply... something computer REALLY don't like. on a dedicated power supply, this is not an issue.

the power supply is only used to power the coil, nothing else on the gun. the gun itself is powered from the USB cable.

I would absolutely suggest powering the coils from a separate power supply. if you must, switch the AC power to the power supplies using a relay and a 12 power supply from the PC so that the power supplies are turned on when the PC is. (I use this setup to switch on a wall mounted 32 inch TV connected to my PC.)

[arcaderX]

Thanks for your reply.  Yes, you are right about the cable from the PSU.  It is a black wire containing two inner wires.

I looked more closely at the wiring because the way I described it did not make electrical sense, even to someone with my limited knowledge.  The picture doesn't show it, but it seems that the terminal block is not wired how I originally described it.  It is like this (which makes more sense to me):

Positive to left socket
--------------------------Positive from PSU
Positive to right socket


Negative to left socket
--------------------------Negative from PSU
Negative to right socket

So I'm happy that it is legit and I understand how it is able to work!

Regarding the recoil, I'll need to experiment firing both at once to see if there's any difference in feel.  If not, I'll probably just leave it.
Regarding attaching the guns to my PC, I think I was not clear (point 4).  I didn't mean to suggest I would hardwire the power to my PCs PSU, I meant I would attach them to the USB ports on the back of the PC rather than use the USB hub, and have the power from the PSU feeding out the back rather than to the front of the cabinet.  Whilst it is a very tidy solution to have the sockets and USB on the front, I don't like the idea of the wires hanging down from the hub.  So, to answer my own question, I think I will leave the DC sockets on the front but disconnect the wires inside the cabinet from the left of the terminal box.  I'll add in my own DC dockets inside the cabinet and attach a short extension cable to each so I can feed all of the wires out of the back of my cabinet.

Thanks again for your comments.

[arcaderX]

Regarding the DC extension cable to power the recoil, will AWG 24 wire be OK?  It will be one extension cable per gun obviously. I don't want the wires melting or anything!  I'm having a hard time getting hold of an extension (in the UK) that has a lower AWG with a male plug and female socket 2.5mm x 5.5mm (which is what I'm using) but I already have DC cables at those sizes with AWG 24 wires, with a length of 1m.

Any ideas?  I'm not sure if I'm reading Wikipedia right but it sounds like they're only suitable for 3.5amps and the PSU is 4amps.

[Titchgamer]

Cable size is not really measured in AWG this side of the pond, Its mostly measured in mm2.

As for the question at hand though, Dont bother trying to buy a extension lead, Just chop into the middle of the output cable and joint it with some 2 core flex.
A bit of 0.5mm should be more than large enough and you can extend it as long as you need it.

[arcaderX]

Thanks for the info.  That would definitely work but I'm looking for a 'tidier' solution.  My guns already have a male DC plug fitted, so I want a female socket for them and then I'll do as you suggest at the other end.

Any thoughts on whether the AWG24 cables will be good enough?  For info, these are the cables I already have and would like to use (I'll chop the male end off and connect to the terminal block shown in my earlier picture) but only if there is no real risk of using them.

https://www.lindy.co.uk/power-c8/power-accessories-c341/1m-dc-power-supply-extension-cable-2-5mm-5-5mm-p5985

[lilshawn]

for future reference 0.5mm square mill is about a 20 AWG

[arcaderX]

for future reference 0.5mm square mill is about a 20 AWG

Thanks

Just for info, firing both guns with the recoils powered from the same PSU didn't seems to make any noticeable difference to the power of the recoil. I'm not saying there is zero difference just that I didn't notice any.  First firing one a few times, then the other, then both together - they seem even to me.  So I will stick with the one PSU for both guns.

Regarding the wiring, I kept both guns plugged in for a few hours with some light use on the guns themselves (single player and two player).  The wires didn't seem to get warm at all.  My garage is pretty cold at the moment though.  So, whilst I'm not advising people (for legal reasons ) to go with the approach I have taken, I just thought I would report back that so far, after a couple of hours of use, there has been no adverse side-effect.  More testing is required but those cables seem good enough for me.  I will continue with caution.

But I would still be interested in hearing thoughts from anyone if they think this is risky.

[lilshawn]

the only time there is going to be any appreciable current flow through the wire will be at the instant it fires. at all other times there will be near zero.

think of it like a lightbulb and a light switch... this is your coil and the control circuit.

flip the switch on briefly then off.  the only time the power is going through the bulb is the instant it's on.

For the sake of example here, the coil behaves the same way. the coil only has power when the computer says "okay fire." and the electronic switch turns on for the split second to make the solenoid pull in.

even if your wire was slightly undersized, you probably wouldn't notice unless you continuously fired the solenoid over and over and over for an hour or more. you would however notice if you turned on the solenoid and left it on (for instance if the electronic switch in the control board shorted in an "on" position.)

fun fact #5348 - you can pull 1,000's of amps through a very small wire... provided you do it for a very very short time or cool it down sufficiently to keep it from melting.

[arcaderX]

That's really useful info, thanks. Makes me feel a lot better.

[Titchgamer]

As Shawn said its a momentary circuit so wont get hot from just sitting there.
However after some extended play you will notice the solenoid will get hot.
Just be careful your transformer wiring does not get hot also.

If the solenoid stayed on for more than a few seconds it would melt very quickly!