Power controller

Simple PWM controller

This 555 timer based PWM controller.The frequency range from about 170 to 200 Hz.Features almost 0..100% pulse width regulation using R1, while keeping the oscillator frequency relatively stable. The frequency is dependent on values of R1 and C1.[more]

Posted in : Power controller | motor controller

ELV Dummy Load for Power Supply Testing

An appliance of some kind is in technical terms a load โ€“ 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 โ€“ often an awful lot of heat![more]

Posted in : Power controller

Cheap Shortwave Transmitter

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 in : Power controller | RF projects

Experimental KW Switching Power Supply

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 in : How to | Power controller

A Slug-Controlled Power Switch

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 in : Power controller | USB projects