This was how I left things in my last post where I was talking about my problems with circuit noise. Can you spot a schoolboy error in the picture above? No? I never spotted it either.
I plugged everything in and switched it on. The background hum appeared and then it disappeared... and then it was back... and then it was gone for good. What? Had I magically fixed the noise problem? Wahay!
Seconds later my elation turned to despair as I realised that I'd only gone and blown the power supply. Damn, damn, damn! That's why there was no noise... there was no power! Oh dear! What an idiot!!!
While I waited for another supply to arrive in the post, I still couldn't figure out what I'd done wrong. It was only when I plugged in the new one many days later that the penny dropped and I scrambled to unplug it as quick as I could.
Having finally got myself a working adaptor, I jumped right back into trouble-shooting my circuit noise issues. My first port of call was to return to power supply "ripple" noise. You might remember that I ruled this out last week, but I had something I wanted to try...
"The most common meaning of ripple in electrical science is the small unwanted residual periodic variation of the direct current (dc) output of a power supply which has been derived from an alternating current (ac) source. This ripple is due to incomplete suppression of the alternating waveform within the power supply." ~ Wikipedia
Hidden at the back of this picture is an LM317T which is a voltage regulator transistor. These devices are meant to be low-noise. Would one of these perform quieter than my collection of resistors? There was only one way to find out.
Long story short... the breadboard above sounded like a bloody machine-gun when I plugged it in to the buffer circuit. I don't know if I did something wrong, but I didn't spend any time stopping to find out. I shelved any thoughts I might have had of using an LM317T on this project and moved on. Pah!
Hold on a second, I almost forgot to share this wonderful video from The Lightning Stalker with you, where he shows us how to break into "Wall Warts". I'm new to the term "Wall Wart" and breaking into them.
I bet you can guess what I was thinking while I was watching this video...
I think for my own sanity that my next post will have nothing to do with electronics. Perhaps I'll tell you about my ambitions to become an expert in Washboard skiffle? Oh yessss! Ha ha.