All posts in the 'Power controller' Category
Posted on 12 May 2008
An appliance of some kind is in technical terms a load – it draws power. We can simulate this using a device, a dummy load, that draws power at a known rate. Dummy loads are usually nothing more than a large resistor. The supply voltage is dropped across the resistor and the energy contained in the supply current is dumped as heat – often an awful lot of heat![more]
Posted on 29 Apr 2008
This is a really cheap and probably illegal shortwave transmitter, don’t build it. It just feeds the output from an LM386 audio amplifier directly into the power pin of a crystal oscillator can to produce AM-modulated shortwave radio frequencies. This works better than one might expect — this particular oscillator seems to provide a stable waveform with voltages anywhere from 2.0v to 5.0v![more]
Posted on 17 Apr 2008
Ralph W5JGV writes:This is an ongoing narrative of my attempt to construct a high-power switching power supply to replace the failed power supply in my Heath Warrior amplifier. Since I use the amplifier for experimental (non-Ham) work, it sometimes has to operate at full CW power for several hours at a time. The original plate transformer is unsuitable for that task, so I am attempting to build a really heavy-duty supply to replace the original power supply.My design concept started when I inherited a large quantity of well-built Dell computer power supplies. They were rated for 230 watts, and some testing showed that the switching transformers in the supplies could easily handle 250 watts. Hmm… If there was just a way that I could make these things put out HV instead of +5 Volts, I’d be all set. Well, to work! [more]
Posted on 03 Apr 2008
This page describes the hardware and software design of a printer power switch controlled over USB from my Linksys NSLU2, aka Slug. The unit can, however, be controlled from any Linux box, and can switch anything, not just printers.There are plenty of power switches out there. Mostly these are expensive things intended for server rooms with RS232 or Ethernet interfaces; USB would be more appropriate for the Slug. One cheap USB switch is this one which has been interfaced to a Slug, but it only seems to be available with continental European sockets.[more]
Posted on 13 Feb 2008
This cheap and easy to build NiCd/NiMH Battery Charger is suitable for automatically charging a wide range of batteries for many applications. Proper chargers are usually expensive and cheap chargers supplied with the original equipment often incorrectly charge the cells and dramatically shorten their life. This ‘intelligent’ charger was designed for high current and rapid charge applications such as cordless power tools and model racing cars. These battery packs are expensive and sometimes difficult to purchase. This charger uses the cell manufacturer’s recommended charge method, to safely and quickly charge batteries.[more]
