Simplest soundcard PWM - Electronic Circuits Projects Diagrams Free

mindoverflow · 3rd September 2008, 03:19 PM

Hi,

I want the output signal of my sound card to swich a transistor, but i still can"t make it work. I saw such a design that used only 2 transistors, a resistor and a diode i think, but i can't find it anymore.

Anyone got any idea please ??

Sceadwian · 4th September 2008, 03:09 AM

Switch the transistor how? Sound card output will switch a transistor just fine if directly connected to the base, for the positive half of the cycle it will be on, for the negative half it will be off as the base is reverse biased, a sound card (without an amp) won't be able to cause a normal transistor to go into base breakdown. You could use a diode to charge a capacitor with a base resistor to act as a low pass filter, but it would greatly depend on exactly what you were trying to switch.

mindoverflow · 5th September 2008, 12:01 AM

here is a schematic of something similar to what i tried.

I used a FEP16BT PNP transistor, i even tried it with a darlington array (uln2003 and 2008) and got no success, if i connect the power supply to the base, the switch works fine. the soundcqrd connection is trought a jack connector, i'm connecting only one chqnel and the ground. I tried it with some music playing. I also tried diodes to always have a positive pulse, but no success.

What do you suggest ???

Best regards.

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3rd September 2008, 03:19 PM	(permalink)
mindoverflow	Simplest soundcard PWM Hi, I want the output signal of my sound card to swich a transistor, but i still can"t make it work. I saw such a design that used only 2 transistors, a resistor and a diode i think, but i can't find it anymore. Anyone got any idea please ??

4th September 2008, 03:09 AM	(permalink)
Sceadwian	Switch the transistor how? Sound card output will switch a transistor just fine if directly connected to the base, for the positive half of the cycle it will be on, for the negative half it will be off as the base is reverse biased, a sound card (without an amp) won't be able to cause a normal transistor to go into base breakdown. You could use a diode to charge a capacitor with a base resistor to act as a low pass filter, but it would greatly depend on exactly what you were trying to switch. __________________ "Because I be what I be. I would tell you what you want to know if I could, mum, but I be a cat, and no cat anywhere ever gave anyone a straight answer, har har."

5th September 2008, 12:01 AM	(permalink)
mindoverflow	here is a schematic of something similar to what i tried. I used a FEP16BT PNP transistor, i even tried it with a darlington array (uln2003 and 2008) and got no success, if i connect the power supply to the base, the switch works fine. the soundcqrd connection is trought a jack connector, i'm connecting only one chqnel and the ground. I tried it with some music playing. I also tried diodes to always have a positive pulse, but no success. What do you suggest ??? Best regards.