Sear's Hobby Page: February 2011

Well M4 CQB Gas Blowback Rifle Review

Posted on 10:42 PM by Benji | 0 comments

Though I have yet to purchase my own GBBR, I still like to keep in touch with the latest offers. The only "problem" I see that they all seem to be M4s and their respective variants. Here now is Well's version of a CQBR:

Bosch relay wiring update

Posted on 10:00 PM by Benji | 0 comments

After reading more articles and doing some trial and error, I realized my last diagram was sorely wrong. In the interest of keeping the number of wires to the minimum, I ignored some fundamentals when it comes to wiring an electric motor using a battery as the power source.

The image above shows how pin 87 is wired to the trigger assembly. With the help of sir Alencore, I learned that this will not work. When I tested this, the arm connected to pin 30 would swing to pin 87 after the battery is plugged but nothing more. This means that the relay is working, but no electrical current will flow to the motor when the trigger is pulled.

In this diagram, I drew the original layout I used for reference. The second diagram shows the negative wires connected to the trigger assembly this time. At first I thought this was not possible. Checking some automotive websites that have posts and threads on Bosch relays say otherwise and the result is a very clean and organized wiring set up. I haven't tried this yet and will post updates when time allows.

Bosch Relay Installation

Posted on 5:24 AM by Benji | 0 comments

Disclaimer: I am not an experienced nor licensed electrician. For those interested in doing this mod, please do your research. The information I have posted documents what I have done and by no means THE method that should be followed.

I've been reading about the use of relays on AEG ever since the use of lipoly batteries became widespread. The main reason for using it is to prevent the trigger contacts from burning up without spending a lot of money on buying MOSFETs.

When I bought my first lipoly, the idea of using a relay also came to mind. Reading threads in FAS and websites on the design and function of the Bosch relay gave me the information needed for this mod. The pictures below illustrate the different diagrams used to wire the relay in the gun.

Prior to the installation, I needed to check space inside the stock to make sure that there would be sufficient room for the relay and the battery. G3 stocks are smaller than M16s, and there is just enough space for a standard 8.4v large-type battery. I did not want to do any sort of modification on the battery compartment that might weaken the structure.

The picture above is based on illustrations I have seen in FAS. A total of four main wires exit the gearbox front and back. With this set up I needed to use 18 gauge AWG wires to avoid any one of them getting stripped or cut once inside the lower receiver. A week after wiring the relay, I test fired it only to learn that one of the wires coming out from the front lost some of its insulation. The culprit was the tight fit of the gearbox in the lower receiver and how mated to the rest of the gun.

Here is another diagram that I have already tried. Notice that the negative wires are the ones connected to the trigger assembly. The positive (red) wires are limited to pin 87 connecting to positive point of the motor. Pins 30 and 85 are connected and then another wire from pin 85 connects to the positive contact of the battery plug. The result, nothing happened. When I pulled out the cover of the relay, I noted that the when the battery is plugged, the way the wires are connected created what is called an "open" switch. This means the no power is flowing through the coil of the relay.

After the last attempt, I muddled over the problem and decided to use positive contacts on the trigger assembly. In this diagram, the wire connected to pin 87 runs through the trigger contacts and then to the positive point of the motor. This means one needs to pull the trigger to make current flow. I will be trying this set up on the weekend and post updates.

For those who read this, please post comments and suggestions. I'd like to get more information on how I can wire my G3 and I'd like to get feedback on the last diagram I made. For those interested, here are the links to FAS and on the Bosch relay:

Basic Car Audio Electronics:

http://www.bcae1.com/relays.htm

Relay- alternative to mosfet by sir Alencore of FAS

http://www.filairsoft.com/forum/showthread.php?t=13299

Poorman's mosfet using Bosch relay by sir Trigun of FAS

http://www.filairsoft.com/forum/showthread.php?t=13299

Helmet Mod

Posted on 9:56 PM by Benji | 0 comments

After returning to playing CQB, I realized it was time to get better protection for my head. In the field or the jungle, one gets protection from the foliage and the distance between players. In enclosed spaces like rooms or narrow corridors, even 350 fps feels like 450 due to the close proximity between shooters. Add high ROF, you come home with more than a welt or two.

So I decided to go and get one. The only problem was that I couldn't find any my size as most helmets were too big for me. So I went to get a cheap helmet (the one in the picture is said to be a scooter helmet but after looking at the construction, I would not even wear it for biking) that I could modify. Here's how it looks:

First thing I did was to sand off the shiny surface to make the paint stick more efficiently. The decals had to be removed with a dremel and the I cut off the visor.

After the initial sanding and cutting, I tested it with a pair of goggles to see how it would fit. So far it looks good though I will have to add some material on the front of the helmet to cover the lining.

From the side, there is a possibility that a pellet could strike between the goggles and the rim on the front of the helmet. I'll be adding material (from pvc) to cover that.

The back seems a little exposed so I will lengthen it a little but no too much that I won't be able to look up without the rim hitting the back of my neck. I also need to add a strap of some sorts to keep the band of the goggles from moving up and down.