Gun Flash unit

[John Clarke]

Hi Robin
I'm most impressed with your recoil system. Very effective.

Not sure how much info you need, so this is all of it.

Flash from a disposable flash camera, open it up, take out the free battery. make a note of all the connections. There will be two switch connections on the circuit board from the camera exposure switch, run two wires from this. Battery connctions, take note of polarity, run two from these. Flash unit connection. Three connections, you will need to keep the construction of the flash unit as it was made but I did trim the screen down a bit so that it would fit into some clear plastic tube for insulation. Put the electronics in a box, add an on/off swtich to the battery wires and a normally open trigger switch to the extended exposure switch connections, extend the flash unit wires so that they can be threaded up the length of barrel with the flash unit in muzzel brake. The battery voltage can be increased from the 1.5volts, but the higher the voltage the faster the charge time. I used 3volts giving me a charge time of about 8 seconds.

I suppose we have to remember that we all may have different systems, My KT has a generic system built by wiggy tronics, but also has the latest
Thomas Benendini system, so I too have the Aux F output. As for other systems I could'nt say. Another problem is radio channels or lack of. I run a 2.4 ghz 10c. which works very well with my tank with lots of channels to chose from. Where as Joe's Comet has the armortek full option and his 10c has a problem with turret and elevation control due to some querk with the 14 ch reciever voltages and the armortek pulse control, This is sortable due to gizmos out there that can boost the outputs on these particular channels .
I was originally going to use a manual system via micro switch on a servo because I had spare channel output (could be done off your recoil servo) to trigger the flash, since the flash circuit takes a few seconds to charge depending on the voltage used to power it, there is little risk of a double flash. But thanks to reading Dennis and Phils Comet builds I was able to utilise aux F with sound sync.

On reflection I had to re-think the relay o/p from Aux F due to others who may not get the results expected, so I'm looking at a opto isolating cct so that there is no contact between flash and sound module.

Nice T34, with recoil and flash, this system might be available thoughout the range. something for all to look forward too.

[Jim Fowler]

Well, I guess we all need to look at Mark and Gill's latest (T-34). Seems Armortek is going to incorporate a recoil and flash in that model - let's all keep an eye on this.

AND, I want to say thanks to Mark and Gill for listening and making this available in the new model!

[John Clarke]

Over the last few weeks I have been trying to make a flash and recoil system that is easier to build and easier to connect to the Thomas Benendini sound board. Joe (Comet owner) and myself want a safe reliable option that fullfils that need. Originally I was going to use just a channel and servo off the R/C and flick the sound switch at the same time. Very crude.

But this system does everything from the sound switch with no risk to the sound unit. Because it's only connected by infra red light.

To get a decent signal output from the sound board, a resistor, R30 needs to be shorted. Not something I really wanted to pursue, it does work, but nobody really wants to take a soldering iron to a £200 double sided circuit board.

Most would love to have a plug and play system, So the plan was to take the low level cannon signal from the sound board as is and convert it to a usable output to recoil drive and flash system, keeping the Thomas Benendini sound board completely isolated from the add on system. It's connected with a standard Y lead so that the machine gun output is also still active.

I don't own any fancy test gear and know very little about electronics, so I got hold of some books and internet info and built a little circuit that does the job.
It uses an opto coupler ( infra red L.E.D. switched transistor) 4N35, this device recieves the signal direct off board direct (Aux F) like the machine gun effect except you only get one flash as it was designed to do. Instead of driving an visable L.E.D. it drives a infra red L.E.D. The ouput signal is too weak to drive relay, so I connected the opto coupler ouput to CMOS logic chip type 4011 quad nand gate. Sounds fancy, but it's not, these chips have been around for decades, the circuit is based on a touch switch circuit because it needs to be sensitive, "one shot" and it is easy to add a timer to the ouput. The ouput of the chip then drives a pair of transistors which in turn drives a double pole relay.
The timed output "on" of about a second serves to switch the flash on (Ex disposable unit) and via the other relay contacts oprates a little servo tester circuit, £4 from china driving a power servo like with Robin' super recoil system. since the flash takes about 8 seconds to charge it will never operate in the same cycle twice. Flash, Bang, Recoil.
All the bits to make are easly available and only cost a few pounds, A simple drawing is below. Just a bit time consuming to make. Care must be taken when setting up the flash unit as it will hold charge and will "bite" if you touch the HV side. I added switches to: switch on/off the flash unit and test the flash unit. I made the flash unit completely stand alone except for the contacts on the double pole relay.

There's no recoil system on my KT due to the blank firer but the flash unit shown here just passes up the barrel for an excellent effect.
Having the muzzle brake on the Tiger and Comet will always look great even during the day

The block of nylon I've machined up for Joe's Comet acts as a slide like Robin's excellent recoil system but internal, not external like his. Still needs work to mount on original mantle elevation lever mount though.

Thanks to Phil and Dennis for their input.

[Jim Fowler]

Well done John! The timing issue you noted is one I too have came up against as well.

Best Wishes!

[John Clarke]

Well I've managed to sort the timing, as always trial and error. Replacing the 10mf capacitor with a 33mf give a true one second time lapse, enough for the servo to move the retract cycle.

The beauty of this system is that everything works in the right order thanks to the Thomas Benendini sound card.

The Comet recoil system is complete and thanks a bit of luck, its a pretty smooth system. Controlled action from the large servo with about 40-50 mm of travel and I've used Tamiya flash tube mated to the camera circuit board because, a) I had one in the "it'll come in useful drawer" and b) it's covered in red coating, giving it a redish flash. sweet.

I'll bang some pictures on the Comet section

Got to spend some time with the KT now. between demands for house decoration. oh woe