I found the inside of an Agilent 33120A looking like this. It runs a little warm without being covered in a blanket of dust! No wonder the output amplifier failed.
A few months ago I was rudely awoken in the middle of the night by the “exciting” smell of burning electronics! I got up fairly quickly and wondered what I could have possibly left on. It turns out it was not a project of mine, but (after some smelling around and unplugging of everything within sight,) my PC power supply. 2AM is a great time to catch fire!
As the pictures show there was a small scorch mark on both sides of the PCB. A blackened resistor is the culprit. I believe the root of the problem was bad capacitors possibly shorting out a power rail. The PSU was making some high frequency noise previously, notoriously caused by bad caps.
To get this far into the power supply I had to pull a lot out. It ended up being a good source of some components, but I never planned on repairing the supply. A good capacitor has already come in handy temporarily repairing an old HP 3478A.
There is a video at the end of the post, check it out!
This is a pseudo-VU meter written in VHDL. I did it for an afternoon project to see what I could do with VHDL quickly. I take the line level audio output from my computer and run it through a Schottky diode ( half wave rectification ), and then straight into a serial ADC. The rest is done on the Xilinx Spartan 3E FPGA.
A true VU meter would translate the volume level of the output signal to a certain DB level. Mine just peak detects the output of the ADC and then scales the output until I get good dynamic range out of the LEDs available. The end result could use some refinement, but I was happy with the rough draft.
I need to clean up my VHDL. I will have it up on github sooner rather than later!
I have to apologize for the lack of posts for the past few months. I have been collecting a good chunk of content but haven’t uploaded it. Expect more in future weeks, I have more time on weekends now to write posts!