Programmable TELRAD Style Finder Scope

thingiverse

#Programmable TELRAD Finder Scope# A Telrad is a type of collimating reflector sight used as a viewfinder for telescopes and other optical equipment. This is a modified, low-cost Telrad design with a programmable reticle that can overlay shapes and text onto the viewfinder. Instead of a glass lens, it uses a credit card-sized Fresnel lens as a collimator. Mounts are compatible with claus57's Weaver/Picatinny rail mounts as opposed to proprietary telescope mounts, allowing it to be mounted on anything with a rail or rail adapter. ##Materials## * Arduino Nano and Mini USB Cable * 1.8" 128x160 TFT Display Module (Model has SD and display pins on the same size as seen here) * Credit Card Fresnel Lens (85mm focal length. Available from eBay) * 50mm Square Mirror (Can usually be purchased from craft shops as mosaic tiles) * 2mm Clear Plastic Sheet (Typically acrylic) * 3 X M3 Lock-Nuts * 2 X M3 15mm Bolts * M3 25mm Bolt * 9 X M2.5 Stand-Offs * 1 X Mini USB Port ##Code## This example code compiles on Arduino 1.8.10: #include <Adafruit_GFX.h> #include <Adafruit_ST7735.h> #include <SPI.h> #define TFT_CS 10 #define TFT_RST 9 #define TFT_DC 8 #define TFT_SCLK 13 #define TFT_MOSI 11 int w; int h; int cw; int ch; int ow; int oh; int rr; Adafruit_ST7735 tft = Adafruit_ST7735(TFT_CS, TFT_DC, TFT_RST); void setup(void) { tft.initR(INITR_BLACKTAB); //Initialise display. tft.setRotation(3); //Rotate display to compensate for reflection. tft.fillScreen(ST7735_BLACK); w=tft.width(); //Display width (pixels). h=tft.height(); //Display height (pixels). ow=-20; //Offset width (pixlels). Edit this value to adjust horizontal offset. oh=0; //Offset height (pixels). Edit this value to adjust vertical offset. cw=w/2+ow; //Centre of width (pixels). Calculate centre of width and align. ch=h/2+oh; //Centre of height (pixels). Calculate centre of height and align. rr=200; //Time between refresh (ms). Edit to change refresh rate. } void loop() { tft.drawLine(cw, ch, cw, h, ST7735_RED); tft.drawCircle(cw, ch, 10, ST7735_RED); tft.drawCircle(cw, ch, 20, ST7735_RED); delay(rr); //Refresh display to update any changes made. }