Sunday, January 24, 2010

Stage 2 begins

Ahh yes, now it's starting to take shape. Up next is the upper receiver parts including the bolt assembly, which will slot inside the carry handle area.

You may notice I re-made the magazine holder - the original effort was the first piece of papercraft I have ever made, so it looked a bit naff.

Wednesday, January 20, 2010

Jan Rukr: the man is a legend

Jan Rukr is the creator of the M-41 Pulse Rifle papercraft I'm building.

Right now, he is in the finishing stages of his latest creation (which he will release to the world when all the bugs are ironed out).

Yes, it's the Sulaco - the Colonial Marines starship from Aliens.

This is Jan's desk in his apartment. What you can see of the Sulaco is about one third of its final complete size, which is about 1.6 *metres* long.

M-41 build Stage 1 complete!

Well, it's*almost* done but there is only three remaining pieces (10 minutes effort total) so I figure I'll call this one complete.

It's really starting to take shape. Hee hee!

Only another five stages to go....

Tuesday, January 19, 2010

Let's go back a step with the M-41

I thought I'd show you the assembly instructions for the Papercraft M-41.

Looks simple, no?


Each of the above pages probably represents 10 hours of effort for a learner. I was figuring 30 hours to complete, but I'm still on page 1 after eight hours and I think I have at least another four to go.

I am making progress though:

This is the majority of the upper receiver, yet there are 28 parts left, out of a total of 65 parts for this component. Glueing these two pieces together is going to be a bitch, because there is a lot of stress at the joins. I'm going to need a lot of glue and then be very gentle with the combined pieces until I get the pistol grip and chamber attached.

Still very keen on getting this done, even with all the effort. I am unsure if this means I am learning better patience as I get older, or if I just like this gun too much. Possibly the latter.

Monday, January 18, 2010

Papercraft M-41 Pulse Rifle

OK so this one is a bit left field. I've been a massive (massive) fan of everything James Cameron for years, particularly Aliens. In addition I'm keen on weapon technology, to which the venerable "M-41 Pulse Rifle" is one of my favourite firearms of all time.

For years, I've wanted a mockup of one, whether it be made of steel or plastic, I didn't care. Unfortunately, the laws in my home state are so severe, that even something which resembles a firearm is strictly illegal. So, my options were limited.

Until in 2003, I found this. Yes, it's a Papercraft model of the M-41 created by a fellow by the name of Jan Rukr.

Here's a pic of Jan holding the completed model:

And here's a couple of profile shots:

Jan provides a RAR file containing images of all the sheets included in this kit, which is 30 pages to be printed on white card stock (250gsm paper). In all, it's about 200 parts, and somewhere near 1,000 folds which need to be made. I've never done papercraft before, but on my first night, I did manage to create this:

This picture shows the result of about six hours of effort. I imagine it will take me something like 30 hours to complete the model, so as I progress through the build, I'll put more posts up. I'm already a bit further in than this pic shows but I can't find my camera for the life of me, so I'll post those updates tomorrow.

I will say this though. It's BIG - and it's 1:1 scale too so the original prop must also have been pretty darn big!

Sunday, September 6, 2009

Epic fail on the X-240 diagnosis

OK so I it turns out I'm wrong about the remote being the source of the noise. After a big session of connection tracing in the remote today, I came to the conclusion that I could just de-solder the audio wires in the remote, and see what happens.

So after doing this, the hum/buzz was still there. Further tracing showed that there is a direct connection between the headphone socket and the subwoofer enclosure and this is not an audio cable. It is probably flipping a bit in an integrated circuit inside the amp which disables the pre-amp (and as a result my previous diagnosis of the amp still being turned on when the headphones are connected is wrong).

Anyway the status therefore is that the noise is being produced within the subwoofer enclosure, not the remote. This makes it a lot harder to fix because this is where the "brains" of the amp are and there are a lot of components which could cause the problem. I still believe it's a design fault or the quality of the components used to hit their price point, but it may be beyond my abilities. I'm going to leave it a few days and see if I get inspired to keep digging.

Oh, there isomething else discovered today: when turned "off" the speakers consume 6 watts of power, and when turned "on" they consume 7 watts. This is pretty poor for standby power consumption, and does not speak well for the environment friendliness of their circuitry. By comparison, my ancient set of Altec Lansing ACS45's (the original plastic-subby version) pulls 4 watts when "off" and 8 watts when on. That's a much nicer difference in consumption - and it even has an "auto off" feature.

Friday, September 4, 2009

X-240 architecture

Well I pulled apart the X-240 last night and - while I didn't fix the problem - I think I discovered the source.

So, the "remote" where the volume control lives is acting as the pre-amplifier (kinda, it's more that it's restricting the "volume" of the input source). Signals come from the PC here and a potentiometer (the volume control wheel) determines how much this signal is restricted - full volume I am assuming is "no reduction in input power" . It's also where the majority of the brains are located, including some additional circuitry which allows for the speakers to be shut down when headphones are connected. And most importantly, when this happens the hum goes away.

This "speakers turn off when headphones are connected" function interests me. It's not like power is being cut to the speakers, just the input source. If you put the speakers close to your ears you can hear a faint hiss, which shows that the power amp is still powering the speakers but is not amplifying any signal.

Further testing also showed that the headphone socket will work even when the speaker system has no power to it at all (even at the mains wall socket). This shows that the headphone connector is mechanically switching the audio input source from the PC sound card to the headphones. Only when the headphones are removed from this socket does the mechanical switch go back to passing the audio input source to the X-240 power amp, via the volume control potentiometer.

Therefore, my deduction is that the noise is coming from the circuitry in the remote. The power amp in the subwoofer box has filtering capacitors on it and shows - by itself - no external noise source. At the moment, I believe that the circuitry in the remote is the source of the noise, or there is noise coming up the power cable from the woofer box.

There are a number of ways I can try to test this, and my ideas at the moment are:
  • Solder in my own separate power lines between the subwoofer box and the remote
  • Hard-wire the power circuit and use the switch on the remote just for the audio connection
  • Hard-wire the audio connection between the PC, the potentiometer, and the output back to the power amp (bypassing the power switch)
  • Hard-wire the power, and also use my own potentiometer for volume control rather than the surface-mounted one in the remote.
Well, that's it so far. Now all I have to do is find some time to run the tests!