Jeri shows how to make a point contact transistor with germanium and phosphor bronze contacts. She cracks some 1N34 diodes to harvest the germanium to build the transistor. Before that she explains in details the physics of semiconductor operation. Finally she tests the transistor in a circuit to find out that it is really working! [via]
Make a Point Contact Transistor at home – [Link]
This project shows how to build a cold coffee (frappe) Machine using plain build materials. On the pages below “Giorgos Lazaridis” describes the procedure of building the coffee/sugar tanks, the raising/lowering mechanism that will blend the coffee and the rotaing glass table. He has to overcome many challenges to achieve his goal and he describes all them in his website. This project is under development.
Instant Cold Coffee Machine – [Link]
MOSIS, short for Metal Oxide Semiconductor Implementation Service is a service that enables you to share wafer space on the fabrication process of a semiconductor. That is a batch order service for custom ICs with reduced manufacturing cost. In practice you share the costs of a single IC fabrication run with other designers. This service is mainly available for Universities and start up companies but Scot Satre of Satre Electronics has used this service for his ASIC ICs.
DIY Integrated Circuit Design with MOSIS - [Link]
Jeri shows how to make blue electroluminescent (EL) powders from common ZnS:Cu green glow powder.
Make Electroluminescent (EL) Ink at Home – [Link]
This article discuss how to make your own LiIon batteries using obsolete Li-Ion pack able to power a robot. The overall cost is about 10$ to build a 14.4V 2.2Ah Li-ion pack. Read about the procedure on the link below.
Making your own lithium-ion batteries – [Link]
This project shows how to build a laser projector using an Arduino, a heptagon pillbox, a cooler fan and a laser pointer. Check how it works and construction details on the link below. The heptagon pillbox scan the projection surface and produced the words. [via]
Because the mirrors are moving the reflected laser dot sweeps the screen from left to right, because it does it very quickly your eyes actually see an horizontal solid line, in this case you see 7 lines one on top of the other because the each mirror is at an angle.
DIY laser projector – [Link]
This project shows how to build a temperature controlled soldering iron based on Atmega8 microcontroller. With this soldering iron you can set the desired temperature with two push buttons. Otherwise you can use three preset temperature buttons. Check schematic on the link below.
DIY Temperature Controlled Soldering Iron – [Link]
This project shows how to build a DIY laser CNC machine using parts from old printers and a CD-ROM. The laser diode using is rated at 1W. With this machine you are able to:
- Cut paper
- Engrave wood and cardboard
- Engrave plastic
- Engrave PCBs etc
DiY: How to build a homemade Router Laser CNC - [Link]
A few years ago I built a keyless entry system for my shop using a keypad, now it is time to update it to use an RFID key-fob. My homemade door actuator was made from parts out of an old VCR. The electronics controlling the system consist of a few components, a NE555IC (timer), a small NPN transistor, and a double poll double throw relay.
DIY RFID Keyless Entry System - [Link]