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Old Jul 11, 2007, 11:34 AM
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Adapting Parkzone Combat Modules To Standard Electronics

First, Alex...don't worry. I know you said not to throw up the schematic until you've done a bit more testing to make sure the device is going to be reliable.

Recently I brought up the subject of converting Parkzone combat modules to standard electronics with Alex. I had done some extensive searching on the net and the only conversion DIY projects I've seen were the two by RC-Cam. He's done an excellent job with that project, even adding several more features to the controller interface functions (lost model alarm, etc).

He has two versions of the project, one for the older modules which is pretty basic (but still more complicated than Alex's hack), and one for the newer modules with the added features I mentioned. The older, more "basic" modification will not work with the newer modules, and the newer project is overly complicated using a PIC chip, software, and other such components to add a bunch of features to the device.

It was interesting to note that the old project wouldn't work with the new modules, since the new modules are still compatible with all x-port equiped Parkzone/Hobbyzone planes. You would figure the trigger function would be the same regardless, but for whatever reason that project isn't compatible with the new combat modules.

His newer "pic chip" project is very nice, and he's done a fine job. Anybody with moderate soldering/schematic reading skills could build it, but most of us don't have a pic programmer and that's a major road block to your average electronics hacker working in the basement.

That's where Alex comes in. As I said, I've found no other DIY interfacing projects on the web for these combat modules. I was rather surprised at this because they are dirt cheap (like $20), can be found at just about any hobby store, and work very well. I happened to have two laying around (we discovered these were the new versions after exposing the circuit boards on them) that I had some moderate fighting time on between Challengers and Extremes. They were GREAT fun but I soon after moved onto standard electronics so they have been collecting dust in my toolbox. I've also got one of those night light modules from them which has like ten different lighting patrens and are very bright. As a sidenote, this device will also work with Alex's homemade device to trigger it.

Last night I took the modules over to Alex's house and he began to hack them. While he was doing some investigating I dug up a few threads for him that decipher Parkzone electronics but they weren't much use to what he needed to know, so out comes the osciloscope (I'm sure I spelled that wrong) and his multimeter. I had the important job of firing the transmitter while he checked frequencies and other readings on the Parkzone receiver and such. I've messed around with 555 chips here and there for timer circuits but what he was doing was WAY over my head. I just nodded yes a lot and acted like I knew what he was talking about.

So long story longer, several times Alex thought he had devised a way to generate a "fake" signal that the combat module would recognize as "fire". The device doesn't look for a simply on/off or high/low trigger at it's x-port input pin (there are four pins...signal in...signal out...and positive/negative power leads), but rather it wants to see a specific coded transmission on it's input signal at a specific frequency to fire. I would guess Parkzone has done this for the reason of preventing it being used by other companies. Probaby also why they grinded off the chip numbers on the boards so you can't tell what they are using easily.

After several false starts (sometimes the device would trigger the module, but fail after the third or fourth "fire" command), he finally found a way to get it to fire every time. You'll have to talk to Alex on the specifics, but I'll put the way I understand it in simple terms for God's less gifted like me. It's sending out a constant babble of "non-sense" over and over again at around the same frequency as what the combat module expects via it's input pin. Sooner or later a random combination of signal patrens fall into the proper language that the module understands as "fire" and does it's thing. Sort'a like a monkey typing on a keyboard (no jokes ), once in a while it's going to hit a random combination of keys that do spell a word.

Alex should be proud of himself because it appears he has done something nobody else has been able to do, unless you are willing to get over complicated with pic chips and such. Good job Alex.

If a plane is hit it's module will already scream for several seconds (very loud) to indicate it's taken fire. Normaly the module would also shut down the engine on the plane for several seconds (the reason for the output and input signal pins on the x-port), but at this time just hearing the thing scream when hit is good enough. Alex says he could easily add a motor disable function to interface with standard electronics later on, but for now this is going to work fine for us.

One final note: He's going to energize his interface circuit via a servo, which we'll probably have plugged into the gear switch. Flip the switch and his interface circuit powers up and begins to generate it's "babble", which results in the Combat Module being told to fire.

I'm sure I got some of this wrong and Alex is going to correct me. He always does. Once again, great job! You deserve a ton of credit.
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Old Jul 11, 2007, 12:04 PM
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Well done guys! I think I have an extra combat module laying around, if I can find it I will bring it to Sagamore Sunday and you are more than welcome to it.
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Old Jul 11, 2007, 12:20 PM
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Spid, the mod is real quick and easy. It doesn't involve opening up the module at all. You just plug it into Alex's interface. RC-Cam manages to squeeze his device inside the combat module's case, so that might be an option.

Why don't you keep yours and do some combat with us? Alex or I can solder up the little circuits for anybody who wants them in NCEF for the cost of the parts, I'm sure. Unless there are fifty people wanting it done. I'm sure we'll probably start bringing a few extra circuits with us whenever we fly so any time somebody wants one they can have it.

One interesting note that we couldn't figure out last night. Doesn't the F27B and a few other Parkzone planes have a lipo jumper on the circuit boards now (and I'm not talking about the newer receivers on some of their planes that come with brushless motors and such)? If so, I believe the voltage output from the power leads on the x-port are straight battery voltage and not using a regulator to output a specific voltage. We did try firing the combat module up at 12 volts (3 cell lipo) but it didn't seem to work. If anything Alex says we'll use a 9V regulator (cheap and tiny from Radio Shack) to fee the combat module, but I'm a bit confused why it didn't seem to want to run on 12 volts. Anybody know if the modules work on lipo powered Parkzone planes? Maybe they say not to use them on lipo power?
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Old Jul 11, 2007, 12:51 PM
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Great work guys, you're on to something fun here for sure!
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Old Jul 11, 2007, 02:30 PM
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Bravo!
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Old Jul 11, 2007, 02:31 PM
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Quote:
Originally Posted by Tommy632
Great work guys, you're on to something fun here for sure!
And a quote from Alex in the other thread of flying this weekend...

I'll likely be there. If anybody wants to do air to air combat, I decoded the parkzone X-port with Tom (critterhunter) last night. I got the sonic combat module to fire on command with two 555 timers and a couple of resistors. With luck I'll be able to make a few adapters on PCBs by this weekend. My airplane builds are on hold right now due to lack of servos/radio equipment

(END QUOTE)

Here we see some obvious errors in judgement and giving credit where it IS due, with Tommy's remark "Great work guys", and Alex saying "I decoded the parkzone X-port with Tom".

Let's get something straight, my only contribution was to bring over the modules and doing some extensive searching in the dark reaches of the net over the last few days for any combat module or Parkzone electronics related info. Alex gets FULL CREDIT for all this because I would have been more help trying to do brain surgery than diving into his homemade signal generator circuit. I can putter my way through some very basic electronics (always been a hobby) but I've got to do a ton of reading to figure out how to build my own custom circuit. In other words, I was no help at all.

Wait, I did suggest we try the combat module on 12V since he had been powering it at 8 or 9V. Wait again...I did have the complicated and overly technical job of shorting the fire button in his parkzone TX on demand since the switch was bad in it too. Come to think of it, I deserve most if not all of the credit for this. I'm just glad I could walk Alex through the whole thing without him getting lost.
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Old Jul 12, 2007, 11:16 AM
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The module adaptor has some problems. I haven't figured out how to hack the output (ie motor shutdown) pin. I have however sucessfull soldered up one module adapter that fires and recieves fire properly.

Basically here's what is happening with that module:

The fire signal period is about 150 microseconds per bit. It has a repeating code 1001000010000000 as a digital signal from what I could see. Repeating that code at 3kHz sampling frequency isn't that easy. I did notice, though that there were approximately 1000 high points per second.

The way my circuit works is it makes a 1KHz square wave pulse at a low (<25%) duty cycle pulsed at 6 Hz at 20% duty. This signal confuses the module and makes it fire. There is a potentiometer on the 1kHz signal to adjust the bandwidth to the module's critical frequency. The signal is basically total garbage, but with some adjustment of the potentiometer, the module accepts it as a valid signal and fires.

The down side is that firing doesn't happen the instant you hit the fire switch. There is a delay between 1/10 and 1/2 second. This delay is random, but can be minimized by adjustment of the potentiometer. Once the potentiometer is set, leave it alone and you never have to readjust it.
You get about 1/4 turn of leeway where the module will fire well.

The other thing the hack requires is a dead servo to dedicate its guts. You can discard the servos motor, case, and gears. You need to hook one of the servo's motor wires (it really doesn't matter which one) to the reset line of the lower 555 timer (this is the 6Hz one). When the reset is low (ie the servo electronics are saying reverse) the module will not fire. However, when the reset line is high (ie servo guts are saying go forward) the module will fire.

I'll post pictures of it when I get the chance. I'll also make a wiring schematic. I am right now working on a throttle mod that shuts down the throttle when you take a shot. I'm also still working on hacking the hit recieved line. Right now when hit is just makes a loud beep. I'm thinking maybe it could force you to reduce to half power or something.
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Old Jul 12, 2007, 01:20 PM
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Excellent work, Alex! Hey, just did some surfing on the net trying to dig up whether the combat module will work with 3 cell lipo voltage (12+). The only blurb I found was this by somebody...

(quote)
Just something to note, but the manual states that only NiMH batteries should be used when the SCM is use. Not sure what the actual implications are of running the SCM and using a Lipo, but it might be good to get some first hand verification that it works okay.
(end quote)

I then went to Parkzone's website and skimmed through the manuals for the 27B, Spitfire, Mustang, etc. I could find no reference to the fact that the X-Port modules should not be used when flying with a lipo. Strange...Perhaps there is a Combat Module manual on there that has that information in it. I'll look...

I know from experience that the old F27B (not the C, which has "standard" electronics in it and isn't X-port compatible) did mutate from the original version to a version which had a lipo/nimh jumper to pick LVC. They also later added jumpers that would allow you set change the elevon controls to rudder/elevator and such. This was done so they could use the same RX at the factory for other birds they sell, such as the J3-Cub, Mustang, Spitfire, etc. So, there have been numerous variations and updates to the Strykers "stock" RX board. I've had the old version (with no lipo jumper), and the latest version (with lipo jumper and control jumpers). Neither of these have any kind of voltage regulator on the board to control output voltage to the X-port. I also confirmed this when I was slapping together my own homemade light module for their planes that would plug into the X-port for power. A quick check with a mutlimeter told me the power pins are passing straight battery voltage with no change by a regulator. This is curious, if the X-port modules do not work with a lipo then they should make that bold and clear in the manuals so nobody destroys one.

So I for the most part got the simply-guy explaination right at how you managed to fire the unit it looks like. The delay in firing (until your constantly outputting non-sense "talk" manages to fool the Combat Module into firing) isn't that long from what I saw. The delay time wasn't even something I could notice, and I'm sure it won't matter much in real world fighting conditions anyway, even if it was longer.

For those who haven't read the spec sheet on the SCM, the module is said to give roughly 80 feet of range. I also know by experience that you do need to be fairly lined up with your enemies tail to produce a hit, which is good. I was worried that the sound waves could manage a kill just by shooting at the other plane from the side, front, etc. Not true, though I'm sure you might get lucky and be able to register at hit that way maybe one out of 20 times or more if the circumstances were right. An interesting addition to combat strategy, if you think about it.

The loud "scream" a hit module makes lasts for 5 to 8 seconds from what I've read and remember. It's very loud and should be good enough in most flying conditions to indicate you've been hit. Still, it would be great to have the option to pulse the motor to mid throttle a few times, not just to help identify a hit, but also to slow a "wounded" bird down a little like it was real life. A mini POT on that to change the duration and extent of "motor damage" would also be cool. Crash and burn builds could have it adjusted to dead kill the motor for a bit like the original module does on Parkzone birds, or raised to only lower the motor for a few seconds to avoid wrecking nice builds. Come to think of it, this could also be used as a handicap for less capable platforms against other birds to make them more evenly matched. The plane with better abilities gets his motor cranked way low on a hit, while the other gets only a mild lowering. I wonder if this could also be applied to the firing consistancy by mis-adjusting the firing POT? For example, the more agile bird's pot is purposely misadjusted so that firing isn't as "instant" as the other plane's module?

Very cool project. You could go so many ways with this thing. LED flash to indicate a hit in lower light flying conditions, etc. Once again, you da man!
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Old Jul 12, 2007, 01:32 PM
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Nope, just checked and no manual for the SCM on the web.

Hey, if you figure out how to change the throttle and thus we don't need the screeching sound from the buzzer (which is a seperate circuit than sonic soundwave emitter), is there any chance of an easy way to make it make a machine gun sound when you fire?
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Old Jul 12, 2007, 02:08 PM
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I think I still have a combat module somewhere. I'd love to get into combat again. I'm not very good at soldering together complicated circuitry, though, so I'll take one of those units for cost of components.
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Old Jul 12, 2007, 04:50 PM
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Saul, if Alex doesn't have the time to build all of them for everybody I'll be happy to solder a few up once he throws me an updated schematic. The one I have is his prototype scribed out quickly that night. I'm also hoping somebody has an old version of the combat module laying around so we can see if his trigger will work with those too. Alex just went out and bought himself a new SCM so, with the two I already have, I plan to carry one as a spare all the time in case somebody wants to try it with us. A quick plug into your gear servo port is all it's going to take, besides mounting the unit on the body (top or bottom) so it's oriented properly. The SCM is very light and shouldn't effect the flying ability of most park flyers. Heck, if a Challenger can carry it then anything can for the most part.

Alex, also be sure to post a parts list and don't assume everybody knows the slang. List the part #, name, and it's specs. Made up example: LM7409 doesn't tell tell average joe that it's a voltage regulator and what it's specs are (window of input voltage, amp carrying ability, output voltage). I have a feeling Radio Shack isn't going to have exact part #s for a few things and we might have to use an equiv. I'm sure they carry 555 chips and I'm also sure they'll have a 9VDC regulator, but it might not be the exact part you list. I know for a fact that diodes are a PITA to track down there, so a few equiv. that should work of those would be helpful to list.

I'm going to try in my limited way to contribute to this project if Alex doesn't beat me to it. I'm pretty sure I've seen audio record/playback IC chips up there for a buck or two. Not sure what is involved to record/playback from one until I head up and take a look. If it's within my skill level I might hitch it between the module and it's speaker to get rid of that shrill sound that goes right up your spine. A nice machine gun chatter when firing will be much more friendly to my ear and add to the experience. Not sure if the chip can drive the SCM speaker but I can always replace that with something it can as well. Only drawback is you'll also hear machine gun chatter when you get hit as it alerts you, which is fine I guess.
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Old Jul 13, 2007, 11:47 AM
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Working schematic for the X-port sonic combat module conversion!

Quote:
Originally Posted by critterhunter
Saul, if Alex doesn't have the time to build all of them for everybody I'll be happy to solder a few up once he throws me an updated schematic.
In that case, Tom, I elect you to build some. I'll give you a prototype to work from.

Current state of the design: I can make the module fire continuously with the motor running, shut the motor off when firing, or fire once, then require reloading (resetting the switch). I think I'm going to make it so your motor shuts off when shooting. That way it's a shooting match, not a carpet bombing.

I also designed a motor regulator circuit that when hit your motor will pulse (rather than shut down like the parkzone planes). This way you still have some power on the plane to stay flying, and you still know when you're hit. I still haven't got the hit line to work, though. I might need a schematic of the module for that. I'll experiment more. Basically I have the hit circuit, I just can't get the module to trigger it. Since I can't get this to work just yet, it isn't in the schematic.

In it's current state, the circuit board will be about 2"X1" or so. I'll see if I can rdeuce the size some by using a single 556 timer inplace of two 555s. Also there is no indication of a hit on this circuit other than the beep the module gives. I'll make revisions later. For now anyone can build this and it will work. You might want to leave some room on the board for the hit circuit whenever I figure it out. I also made the schematic in MS Paint as I doubt many people have P-spice or MicroSim.

Anyone is welcome to this design. I offer it up here for free. Have fun with it and feel free to ask any questions. The only request I have is that you give credit where it is due

-Alex
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Old Jul 13, 2007, 02:02 PM
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Great work, Alex. Throwing this entire thread onto RCUnivese for people to build one. You're going to be one popular guy real soon. I'm going to add a "NOTE" to the top of the thread that says not to PM or email anybody to build one. That privilage is for NCEF members only or you'll/we'll be swamped by PMs asking "PLEASE BUILD ME ONE!". I'll also throw up a disclaimer that says playing with this circuit could damage equipment, cause a fire, or cause your wife and kids to leave you so nobody has something to complain about.

Hey, you have a lot of time on your hands too, I guess...You just do something more constructive with it. I'd be happy to solder up a few for people. There are a couple I want to make "special" boards for. Just a joke, don't call home land defense on me.

I like the "fire and have to reload" idea. Any cheap and easy to make all these features variable like I discussed in the above message via dip switches, a pot, or?

A few things to clearify for us common folk who aren't the brightest bulb on the neon sign...I guess you are saying that you haven't been able to hack the output signal wire from the module yet to use as a source for triggering a motor slow down? If I'm understanding you right, then why not use the audio speaker wire's output in the SCM as your trigger to identify a hit, or some other point on the SCM circuit board to monitor it? Please clearify.

It would be a more clean setup if you can hack the output signal from the SCM, because you wouldn't need to open one up to mod. Just plug it into your homemade interface and all is done. On the other hand, I guess you could remove the output trace line before the x-port plug and then route whatever point on the SCM you are monitoring for hits out that pin. That way you only need to open the module up once to jumper that signal to the x-port plug, and your "hit" circuit can monitor it outside the unit. You still think you can't fit your interface inside the SCM case? I'm up to the challenge of experimenting and trying, and will.

On another pointless aspect of this subject, I think I might be able to stagger my way through the machine gun sound mod. Or, how about recording a nice piece of action soundtrack from a movie along the lines of the Terminator?

I was just up at Radio Shack and was looking for the IC sound record/playback chip they used to stock. No dice, but I did notice they have a tiny complete project board (no case on it) already wired up using this chip for about $10. It features the chip, a few electrolytic capacitors, and a "record" and "playback" button on it. That's it, and the unit will run on 9vdc. It's very tiny and light, and could easily be made even smaller once you trim the board edges off and remove the record and playback push buttons. The unit will record up to 20 seconds of audio and it stores it in static memory so you won't loose the recording if power is removed. This one could work well!

Didn't pay much attention to it's speaker specs but the one that comes with it is roughly the same size as the one in the SCM. Which one is louder or if it will drive the SCM speaker is still yet to be checked into. If it won't drive the SCM speaker and isn't very loud with it's stock one, I've already scoped out an audio amplifier IC chip they have for like a $1. They also still carry 555 timers, as well as the dual 555 (556) timers on one chip, so we are in business there.

How to fire this audio module? Simple and direct for me would be a tiny relay that is energized from the speaker wire outputs on the SCM. When closed the relay contacts will take the place of the push button removed from the audio circuit. The speaker output leads from the SCM probably don't put out a clean and steady DC voltage (I have experience with this type of hack when I made some homemade deer trail cameras triggered via a infrared motion sensor), so perhaps a diode will clean the signal up (allow the voltage to go only one way) enough to trip the relay. I'm sure the audio circuit only needs a momentary contact of the push button switch to get it to play the entire recording, and doesn't need to stay closed while playing. Wouldn't make much sense for a device like this.

Next option that might be lighter and/or make more sense then a tiny relay...Some simple circuit that will ground the play button leads momentarily. I can hack my way through that with a little reading, but I'm sure you have that on the top of your head.
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Old Jul 13, 2007, 03:16 PM
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Alex, threw a heavily edited transcript of this thread up on RCUniverse in the Park Flyers forum. Notice the huge and paranoid disclaimer at the top.

http://www.rcuniverse.com/forum/m_61...tm.htm#6107148

If you want something changed or added to it just let me know.
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Old Jul 14, 2007, 09:49 AM
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Alex, once again re-edited that thread (Put a full credit disclaimer at the top noting that you are the Golden Boy who did everything). By the way, you forgot to add the pin out numbers to the diagram for us lackys.
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