Summary The infrared (IR) is invisible radiant energy, electromagnetic radiation that we cannot see with our eyes, but we can sometimes feel on our skin as heat. The infrared light falls just outside the visible spectrum, beyond the edge of what we can see as red. Most of the thermal radiation emitted by objects near …
When working with discrete JFETs, designers may need to accommodate a large variation in device parameters for a given transistor type. A square-law equation is usually used as an approximate model for the drain-current characteristic of the JFET: ID=β(VGS−VP)2, where ID is the drain current, VGS is the gate-to-source voltage, β is the trans conductance …
Hardware/software combo can create professional schematics from undocumented PCBs Fairport, NY. The Rev Eng. System is a remarkable reverse-engineering hardware tool for creating professional quality circuit schematic diagrams from a sample PCB that lacks documentation. The Rev Eng. System consists of a PC-controlled continuity-detecting hardware system, Rev Win control software, and Ed Win, a fully featured …
This is a fly back SMPS that will boost voltage a voltage of around 20V to 40V, or more if you change the feedback resistors. It uses an off the shelf transformer from Coil Craft. The LM3479 is a nice controller because it’s frequency of operation can be set by changing R1. At 39K it …
Lithium-ion batteries are sensitive to bad treatment. Fire, explosions, and other hazardous condition may occur when you charge the cell below the margin that the manufacturer defines. Modern battery chargers can manage the hazardous conditions and deny operation when illegal situations occur. This fact doesn’t mean, however, that all cells are bad. In most cases, …
Simple circuit indicates health of lithium-ion batteries Read More »
This is useful tip for anyone making or using surface mount components on PCBs. It relies on access to a laser cutter, so if you don’t have one, look away now….. I cut a plastic stencil on the laser, align it with the PCB pads and then squeegee a thin layer of solder paste through …
If you have used LCDs in projects before you have realized that to use the backlight on a LCD display you need large positive and negative voltages. This circuit will help you create the voltages you need from a simple 2.5V to 6V input. I chose this circuit since many of my projects run off …
If you have an H-Bridge drive circuit for a motor, you may need a way to monitor the load on the circuit. This circuit is nice because it provides a single output that could be monitored with a microcontroller or other device. The trick is to use current sense amplifiers and measure the current on …
We route all our PCBs manually instead of using an auto router. This can be a tedious job sometimes, but we think it gives the best results. Sometimes we’re just about to finish a PCB, when we notice a MUCH better way to route it if only a few connections could be changed. The Gateswap …
Most commercial LED flashlights use three AAA or AA batteries in series that produce 4.5V. The batteries then drive four white LEDs that connect in parallel. These LEDs can work at voltages as low as 2.7V and, in some cases, 2.4V. At those voltages, the LEDs become dim, and you must frequently change the batteries. …
LED-flashlight circuit works at 0.5V low voltages Read More »
