rapid fire units

D · Post by D » Mon Oct 10, 2005 2:58 pm

Where can I get info on this?

Do I need a 60 firings per second rapid firing unit?

Can I make it so that I put rapid on button 3 and then when I press button 1 it overruns the rapid firing unit.

How do I do it.

dpful · Post by **dpful** » Mon Oct 10, 2005 4:44 pm

There used to be a post on here that had a schematic for a rapid fire circuit that works great, and the button3/button1 trick should work fine (since the circuit just interupts the ground). But I can't find it- I may have been from before the forum reset.

I believe I got the diagram from Matt

SAM · Post by **SAM** » Mon Oct 10, 2005 5:34 pm

dpful wrote:There used to be a post on here that had a schematic for a rapid fire circuit that works great, and the button3/button1 trick should work fine (since the circuit just interupts the ground). But I can't find it- I may have been from before the forum reset.

I believe I got the diagram from Matt

I guess you just connect the wires as follow:

button1 => The Fire Input
button3 => Auto Fire circuit => The Fire Input

When only button3 is pressed, the auto fire circuit would generate a string of "101010..." signal; but when both button1 and button3 is pressed, the wire of button1 would short the circuit and thus give "111111111....".

Try it, this should work.

D wrote:Do I need a 60 firings per second rapid firing unit?

I don't think 60Hz is a good idea, unless you are pointblanking the target. Since in most shmups the max number of shots you can have on the screen is limited. If you fire all of them in a single brust, you won't be able to fire any shot until the fired shot is either hit somthing or leave the screen. I think a continuesly stream of shots is more useful.

By the way, I think Auto Fire Circuit need external power, anyone can confirm this? Anyone know how to build such a circuit on your own using chips?

D · Post by D » Tue Oct 11, 2005 8:52 am

Well, can I use a autofire unit from some controller?

And I do prefer point blank 60 Hz firing!

Can it be adjusted?

B.U.M.P.

SAM · Post by **SAM** » Tue Oct 11, 2005 11:03 am

D wrote:Well, can I use a autofire unit from some controller?

Yes, if you can saperate the autofire circult from the controller singal encoder. Also an power supply would likely be needed for the autofire circult.

D · Post by D » Tue Oct 11, 2005 11:20 am

SAM wrote:
D wrote:Well, can I use a autofire unit from some controller?
Yes, if you can saperate the autofire circult from the controller singal encoder. Also an power supply would likely be needed for the autofire circult.

I've seen some of those dedicated rapid firing units for the Sega Master Systen, they should also work for Megadrive games. I'm thinking of getting one (or two) of these. Will it work? how many firings per second?

Why ask questions nobody has answers to? I'll check on SMSpower.org for this

dpful · Post by **dpful** » Tue Oct 11, 2005 3:57 pm

I'll try and dig up that diagram. It worked great- ran off of the 5v from the arcade buttons.

*edit
I don't have it anymore- you should pm matt.

Repid fire circuits from console controllers would be difficult.
but they probably run off 5v too.

D · Post by D » Wed Oct 12, 2005 7:58 am

dpful wrote:I'll try and dig up that diagram. It worked great- ran off of the 5v from the arcade buttons.

*edit
I don't have it anymore- you should pm matt.

Repid fire circuits from console controllers would be difficult.
but they probably run off 5v too.

well, i allready found this>http://www.smspower.org/smscartpad/rfu.htm

But, I live in the Netherlands.
Is there an easy way to do it, the rapid fire unit could great, just wire 5 volts to the rfu then back to ground and attach buttuns to it!

SAM · Post by **SAM** » Mon Nov 07, 2005 3:34 pm

D wrote:well, i allready found this>http://www.smspower.org/smscartpad/rfu.htm

Wow!!

You guys are incredible!!

Now I know how to built an auto fire circult...

Just took a quick check and found Saturn, MegaDrive and Super Nintendo all supply +5V to their controler's IC...

Plus the working voltage of most PCB is also +5V. So I really don't need to buy the Sanwa auto fire PCB...

D wrote:And I do prefer point blank 60 Hz firing!

Well, I think you idea is to have to highist possible rate of fire. And you assume the game is digitialize your command inputs by deviding the input into short time intervals at the same speed as the game's frame rate, and that is 60fps.

Let assum your assumtion is true, the max thoertical rate of fire is actually 30Hz instead of 60Hz. Because, if you are firing at 60Hz the game would got ON singal for every frame. It would then treat the inputs as the fire button is being HOLD.

So you in order to registered firing another shot, you have to let the game detact you release the fire button and thus the highest possible rate of fire is to hit the fire button every other frame, and that is 30Hz.

So firing too fast would actually decrease the rate of fire.

60Hz = 0sps (Shot per Sec)
59Hz = 1sps
58Hz = 2sps
...
...
31Hz = 29sps
30Hz = 30sps
29Hz = 29sps
...
...
3Hz = 3sps
2Hz = 2sps
1Hz = 1sps

P.S. - the Sanwa Auto fire PCB got option to fire at 30Hz or 15Hz.

dpful · Post by **dpful** » Mon Nov 07, 2005 4:38 pm

D wrote:
dpful wrote:I'll try and dig up that diagram. It worked great- ran off of the 5v from the arcade buttons.

*edit
I don't have it anymore- you should pm matt.

Repid fire circuits from console controllers would be difficult.
but they probably run off 5v too.
well, i allready found this>http://www.smspower.org/smscartpad/rfu.htm

But, I live in the Netherlands.
Is there an easy way to do it, the rapid fire unit could great, just wire 5 volts to the rfu then back to ground and attach buttuns to it!

That diagram looks very similar to the chart I used to have. Easy to make.

Post by **Dave_K.** » Mon Nov 07, 2005 7:32 pm

I've seen this 555 circuit before. Only problem is you don't know exactly how fast your rate is if you use the variable resistors. You can do the math to set the resistor values for exactly 30hz, but if your game isn't using exactly 60hz refresh you will not be sending the optimal autofire output. This is why circuits that use Sync as input and divide the signal is best, like the one posted here http://galford.hp.infoseek.co.jp/sync.html which can divide the signal up to 7 times for variable autofire output.

[edit]
I take that back, the best circuit design is one that takes sync as input and lets you program on/off values per frame as mentioned in BER's thread here:
http://forum.shmups.com/forum/viewtopic ... t=autofire
Since this seems way out of reach for most hobbiests, I'll just take the galford circuit mentioned previously.

[/edit]