Class D amp using LM319 comparator

Finally! I`m back from long hiatus!

As the subject title implies, yes. LM319 is not a popular choice as integrator/differentiator combo due to it`s output pull-up resistor which is not good to directly drive capacitive load. Although it was being claimed by chip makers as fast comparator, they mean it’s fast enough as digital pulse generator for driving TTL/DTL logic gates. This means it can generate decent PWM pulses intended for class d amp purposes but at different, or should I called it harsh method as shown in schematic diagram of Fig. 1 below.

Continue reading “Class D amp using LM319 comparator”

Active crossover network using 555 timer as class d amp

Perhaps some of you have already seen my blog in DIY audio forum showing practical use of 555 timer as class d amp source. Indeed, the circuit is quite an interesting subject to exploit specially to some curious folks looking for cheap but good sound class d audio amp project. The same circuit is shown in figure 1. Continue reading “Active crossover network using 555 timer as class d amp”

Class D amp using TL494 DC to DC converter chip

Class D amp using TL494 DC to DC converter chip

It’s almost 5 years now since I published a topic regarding how to use TL494 as class d amp in a popular DIY audio forum. I think it’s quite good to include this article here also. By the way, before I publish that topic I thoroughly googled the said subject to see if there are some geek guys who have already done such a playful exploit of this chip but I simply got zero hit. This could mean that I am an early bird on this regard? Or maybe I am the only one who have a bizarre taste in choosing the right chip for such an application. Continue reading “Class D amp using TL494 DC to DC converter chip”

2 channel 555 timer class d amp source

It’s more than one month now since I updated my last post and I regret that I couldn’t post anything within that length of time. This is due to the nature of my job. We left Tilbury last month and now we transferred here in Bremerhaven shipyard and our ship is still being dry docked for repair. Unfortunately we still don’t have any internet connection and our satellite is still under repair too. I just rely on outside wifi access so, this is my new follow up post as continuation for the unfinished topic for that post below. Hopefully, I will make a new post again if our internet connection will be restored soon.
My last article was still 555 timer so this is another neat idea how to get more useful circuit out of your 555 timer. I think it is not good to move on to another topic using another chip because every time I made a circuit out of this 555 timer, another idea pops-up in my mind to share. Continue reading “2 channel 555 timer class d amp source”


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”