If you have ever wanted to plug in a pro-quality microphone and headphone to an iPhone or iPod touch, pay attention and read on. This guide will show you how to make a cable that will allow you to do just that. It’s not that hard as long as you can solder well, and can locate the right stuff. But in the end, you’ll end up making a little dongle that will allow you to plug in a mic and headphones separately.
Posted on Wednesday, December 29, 2010 • Category: Antennas
This simple 7 element Yagi is ideal for portable operation. The elements can be removed and replaced in a few minutes. The 2.42 Metre boom will fit inside my car. All of the elements are made from 6mm solid aluminum rod. The boom is made from 50x25mm (2x1 in) timber. The driven element is a half wavelength dipole. Unlike the more common type of folded dipole, this dipole is folded on one side but not on the other. For want of a better name, lets call it a 'half folded dipole'. The co-ax cable braid is connected to the centre of the dipole. The co-ax centre conductor is connected to the folded dipole section (see diagram above).
Posted on Monday, December 27, 2010 • Category: Miscellaneous
Using the GPS Satellite system offers the advantage of very accurate timing and by extension, frequency control. The long term error is to all intents and purposes zero, with time and frequency accuracy being comparable to the international standard. The traditional route is to use a relatively low cost GPS receiver module which outputs a 1 Pulse per second signal (1 PPS) aligned to UTC. Basic GPS modules such as the Garmin GPS25 and Motorola Oncore have been around for some years and are available at low cost. It is possible to phase lock a divided down crystal oscillator to this 1 PPS signal and transfer its long term stability to , say, a 10MHz reference which is subsequently used for deriving any LO and beacon frequencies. The subsequent PLL system is usually described as a GPS Disciplined Oscillator rather than locked, since it is not, strictly speaking, actually ‘locked’ to the GPS system at all; just controlled by it via the 1 PPS generated by software in the receiver module.
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