security alarm circuit

Osmond PCB  ^new - Printed circuit board design for Macintosh

60 W Linear Amplifier Circuit - The 60 Watt linear amplifier is simple all solid state circuit using power mosfet IRF840.

Cheap Crystal Filter - An economical way of building an SSB filter. The circuit is for a filter with a 6 DB band width of roughly 2.2 KHz.

PC Headset Adapter for Ham Radio - A PC headset to Rig adapter. Include a circuit diagram and a full part list for the project

Morse Keyer Circuit - This is not a sophisticated automatic keyer but it is lot QRP to build and to have fun operatin

600v Power Supply - A 600 volts power supply for QRO

Icom CI-V Interface - Build this CI-V interface and the additional circuitry to provide PTT from RTS.

Sound Card Interface with Tone Keyer - An improved version of the audio interface commonly used to connect a computer soundcard to a transceiver\'s receive and transmit audio circuits

RF Probe for HF - A RF Probe circuit for the RADIO frequency experimenter to check the presence of a RF signal and also to measure its strength

RF Probs and Watt meter - This RF probe can be used at High Frequency (HF) or Ultra High Frequency (UHF) on both 50 and 75 ohm coaxial cables.

A DIY Square Wave Signal Generator - This circuit is very simple and has a fantastic range of potential uses.

ZL2PD HF RF Signal Generator - This circuit came out of some work done for two antenna analysers