I've modified my Milestag UMT design to correct a problem with the original.
The problem is that the muzzle flash LED is wired in parallel with the infra red LED:
This is an issue because the forward voltage of the IR emitter is 1.35V, and that of the muzzle flash LED
is 2.1V. This results in the muzzle flash illuminating far below its potential.
My new design has two outputs, one for the IR LED, and one for the muzzle flash LED. Both are driven from the same MOSFET
but the current limit resistor is dedicated to the IR LED:
The muzzle flash LED will require its own current limiting resistor, but this matches the original Milestag design.
Here's the PCB, it will be available as a kit at TAGBITS in a few weeks:
Wednesday, 18 January 2012
I've been continuing the development of my budget Milestag gun kit. This is designed to have a single sensor on the gun body to reduce the cost of the unit. Initially I've concentrated on the sensor electronics. I've created a kit to make a Milestag sensor: Tagbits Guns, I've designed a special mount for this sensor type. I'll be building the gun in the next few days:
The Milestag CORE and UMT PCBs use 0.1" Vero connectors. These are a pain to use in quantity as every cable has to crimped manually. I've started using AMP 0.1" IDC connectors instead. These are much faster to wire:
Monday, 16 January 2012
Whilst getting ready to try out my single sensor Milestag gun I decided that I needed to re-design the battery cover on the gun body. Previously this had been quite thin and had chamfered, circular tabs that were proving difficult to print as the filament often failed to adhere to the layer below as the radius increased with the chamfer:
Thursday, 12 January 2012
Wednesday, 11 January 2012
Here is a pic of my RepRap complete with heated chamber, acrylic door and filament spool holder. It's printing a grip section from one my Milestag guns.
Monday, 2 January 2012
I've been asked by several people whether it would be possible to mount a sensor on the gun bodies sold at Tagbits so I re-designed a sensor mount to fit onto the forestock section. When fitted with a 3 way milestag sensor this should allow for a low cost solution, but will allow body mounted sensors to be added later if required: Milestag Gun picatinnny rail mount to be higher. A second sight.
After my extruder mount failed the other week, I declared that I needed to stock up on spare parts for my RepRap. I've printed this set of bits which is all but one of the components that I have identified as critical.