K8NOW Radio Club

K8NOW, Rag Chewers Net, MARC, ham, radio

Project 2

 Home built Laser Engraver

 

This project is a home built Laser Engraver. It used many salvaged parts, the basic parts list is :

  • Arduino Uno
  • GShield for the Arduino
  • Stepper Motors and linear guides from 2 DVD Drives
  • The Laser module, more info below

As you can see in the photo below, the results are great. Here you can see a sample of the quality, engraving some simple text on a Popsicle stick.

 

The construction of the Engraver and the setup info is all available on the internet. The hardware is nothing more than 2 used DVD drives, using one for 'X' side to side, and one for 'Y' up down movements. There are mounted on a frame to align their operation. The electronics used is an Arduino micro controller, and a GShield, which plugs onto the Arduino. The key component to this is the Laser. There are many articles on building a unit using Laser Diodes, I did try this and it works, but the power of the diodes are low, making for a slow process. I finally bought a prebuilt 1 Watt unit mounted in a housing with a lens, fan, heat-sink, power supply and TTL controller.

The Software to run this is:

GRBL for the Arduino to send the GCode commands to the GShield that then drives the Stepper motors.

InkScape - a simple drawing package for the artwork, that outputs the Gcode file needed to drive the laser .

GCodeSender - this interface allows manual and automatic control of the Arduino an GShield.

 All this is controlled from a computer (PC, Mac, Linux, and yes XP too).

PROJECT 1

This is a 2 Meter / 220 Notch filter

As you can see, construction of this notch filter is in a tuna can. I built this to reject RF from getting into my TV antenna preamp. Since I use over the air reception for local TV, I have several tuners that will overload when transmitting on 2 Meters and on the 220 Band. In particular the 2 repeaters used during the Sunday night Nets.

[ See the MARC Net Schedule on the Main Page. ]

Using 75 ohm cable TV coax, I used the center conductor to support one end of the coil, and the other end of the coil connected to a variable cap. This makes up the classic L/C circuit. The center of the tuna can is divided down the middle for separation of the two circuits. The sizes of the coils and caps were picked based on an online program I found – I basically guessed at the coils – 11 turns around a ¼” form, for 2 Meters and 8 turns for 220. The variable caps are slug type –from the junk bin. I was going to use the flat type but they would be harder to support in the can. As you can see by the printout from the spectrum analyzer the notch at the repeaters input frequency is quite low at a -50 dBm for 2 Meters and -54 dBm for 220. Also you can see the reference signal is shown at -17.70 dBm, the pass frequency in the Digital TV band is low at around -25 dBm, but since the output from this filter goes into a preamp, I see no signal loss at all my TV’s and tuners.

Hope you liked this project, more to come.

 see-ya, Pete N8OER