Surf PI efficient and simple speaker driver for low impedance speakers.

[Vadim18]

Hi!
This circuit based on comparator so it produces well sharp shaped pulses at the output and drive low impedance speakers. In this video i drive a cheap 6 Ohm speaker with aditional 47 Ohm resistance.
circuit

video

https://youtu.be/ZKQLycUPBV4

Ready for comments, critic and tomatoes.

[sinclairuser]

nice, but the schematic is a bit confusing, c1815, a1270, bc548, bc557 and mpsa 13 are all mentioned but which did you use?.
as for the mpsa13 i have found that mpsa14 is easier to find and has more gain, the mpsa13/14 is a good replacement for some darlington paired transistors too.

[Vadim18]

Hi Sinclairuser!
Yes, i redrawn circuit. I use two C1815 and a1270. I just have this transistors and last one is power related for load driving purpouse. Thanks for your knowledge, last time i combined two transistor to make a darlington pair and had better results than with mpsa13, for next time will look for msa14.
Heres the circuit.

[Vadim18]

Some minor corrections for circuit and SMD layout

Smd 15x15mm PCB
SurfPI_speaker_driver_SMD_PCB.zip

[sinclairuser]

thanks vadim18 for clearing that up, nice simple mods like this can make all the difference sometimes.

[Vadim18]

Well, 2 years after i find what the problem is.... that's all about DC component during transitions, thats why Surfmaster work well only with piezo

[Vadim18]

Here is alternative solution with some small bonus and simulation
If anyone interested in microcap sourses i attached all in zip file

[Vadim18]

Here is link to Micro-Cap on web archive https://archive.org/details/mc12cd_202110