Photo. This is the test circuit -the basic driver is only two transistors, two resistors, the circuit was evaluated using a white LED, but when it was time to button it up and archive it, I replaced the expensive white LED with a cheap green one. Othere LED Driver Circuits on this site: White LED […]
Series Connected Voltage Boost Circuit for a Battery Operated LED Lantern Read More »
What it is The circuit allows a precision regulated drive current to be set to drive an LED, and in response to a TTL level signal, the LED is switched on and off with rise and fall times of less than 500 nanoseconds and less than 7% overshoot. This was designed for biological experiments to
FAST PRECISION LED DRIVER Read More »
Three inductor-free circuits that allow a white LED or UV LED to be driven from one (1.5 volt) or two flashlight cells (3 volts total) are described. The circuits on this page are: The two cell (3 volt) circuit four transistors. The simple single cell (1.5 volt) circuit requires six transistors, but it isn’t as
Single and Two Cell White LED Drivers Without Inductors Read More »
Download FreePC project file, gerber and png copper and silk-screen: 1wattledbuck.zip Introduction I have some 1 watt warm white LEDs left over from a project and the application for them was obvious: A better battery operated lamp for use when the power fails, which it does frequently, especially during the rainy season. And this one should
1 Watt White LED Power Supply Circuit for battery operation Read More »
Overview The circuit shown in Figure 1 is capable of driving an LED array requiring up to several amps with a burst of flashes before coming on until power is removed. It is intended to be used as an auxiliary warning light driver. The initial burst of flashes is meant to enhance visual detection of
Attention-Getting Auxiliary Warning Light Flasher/Driver Read More »
An adapter to allow low capacitance probing of high frequency circuits. Overview My boss, Dave, said “Just hold the probe close to the cathode lead.” Dave had worked at Tektronix for many years, and his ability to make difficult measurements was second only to his abilities to manage a company and design clever circuits. Dave’s
Low Capacitance Scope Probe Adapter Read More »
Overview I needed several current probes when designing the deflection circuits and high voltage supply for a computer display monitor, and the lab in which I was consulting only had one current probe, which I shared with the other four engineers on the project. We did not really have a budget for test equipment on
AC Current Probe for Oscilloscopes Read More »
Introduction It has been said that a man with one watch knows what time it is, but a man with two watches is never sure. The same can be said for a person who has more than one voltmeter. In my situation, I have several voltmeters in each of two different locations a third of
A Portable Precision Voltage Reference using microcontroller Read More »
Not too many parts. When a voltmeter is connected across the outside terminals of the output connector, its display reads out in degrees C. I’ve been fascinated by the LM335 for some time -maybe my obsession with stability finally gave way to my fascination with a circuit with intentional thermal drift. I finally bought some
Simple LM335 Thermometer using microcontroller Read More »
Downloads Download the Download FreePC files in and the detector board layout png file in zipped forma: schottkydedtector080309 Find updates at www.projects.cappels.org Starting to do a little work at 330 MHz, I decided that my existing field strength meters were not adequate for for my needs. The 330 MHz project came to a stop, and
A Field Strength Meter Using A Biased Schottky Detector using microcontroller Read More »
