I’m an avid collector of LED for 28 years and I was impressed how fast the technology grows in a very surprising rate. Take for example those 5 mm white LED that you can see from bargain key chain lights and small flashlights to a very bright signal lights on pedestrian lanes, traffic stop lights and most recently from residential and commercial setting as well. Continue reading “MCE Cree LEDS”

Sound Card Oscilloscope

sound card scope 1.32

As an electronic hobbyist, I always wanted to own a sound generator good enough as signal source for my audio test needs. Since most audio test instruments available are expensive and some are bulky to occupy my work bench, my options have been narrowed down when I came across on the internet a program called “sound card scope 1.32” by C. Zeitnitz. This program is free for private or public educational use but please read the license agreement from the author regarding this matter. Continue reading “Sound Card Oscilloscope”

Bias scheme for 555 timer as class d amp

I’m almost in the process of preparing another article to post but my attention was diverted again to the previous 555 timer circuits I made. I simply couldn’t afford to leave the circuit that way. I am concerned that by changing the 2N3904 with the same type of transistor but of different hfe, the duty cycle changes accordingly and this is annoying. Continue reading “Bias scheme for 555 timer as class d amp”

Full bridge class d amp using 555 timer

Ok, I’ve been so busy for the past few weeks and I couldn’t make a follow-up from the last article of the 555 timer circuit. So here is another improvised model circuit that will eliminate the unwanted DC offset voltage from the output that affect the previous one discussed. By the way, all previous circuits that I discussed were intended as “low power” class d amp source that is adequate to drive head phones via a coupling capacitor. Continue reading “Full bridge class d amp using 555 timer”