You can construct your own long range infrared (IR) wireless remote using Motorola's MC145026 emitter and MC145027 detector chips. With your remote you can control devices up to 20 feet (7 meters) away. It operates similiarly to a TV remote. You just point the emitter at the detector, push a transmit button. The detector then interprets your data signal. You can use this circuit to remotely turn on/off devices (like a motors, relays, home appliances).
Build Accurate LC Meter and start making your own coils and inductors. This LC Meter allows to measure incredibly small inductances making it perfect tool for making all types of RF coils. LC Meter can measure inductances starting from 10nH - 1000nH, 1uH - 1000uH, 1mH - 100mH and capacitances from 0.1pF up to 900nF. The circuit includes an auto ranging and reset function to make sure the readings are as accurate as possible ... [more]