New Oscilliscope Part 1 – Disassembly

We were cleaning out the lab at work, and throwing out older lab equipment, and I scored a Tektronix TDS 544A. The sticker indicated it needed to be repaired and calibrated, and it just wasn’t going to be worth it, so they were tossing it. I scooped it up, and I’ll have a few blog posts about the repair process. First, the good – It’s a 4 channel 500MHz digitizing scope with a color CRT screen. It beats the heck out of my older TEK T935A, which is an analog 2CH 35MHz scope. I think the biggest win is the ability to stop the scope and look at a trace, as well as much more powerful triggering options. Powering it on, it has a few faults in the self diagnostics, and research online shows that the main problem with scopes from this era are the aluminum electrolytic capacitors on the main […]

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Extruder fan controller

I brought my makerbot to the Reading Friends and Family Day to show at the Reading Robockets booth. I’ve been having some issues with the extruder skipping, and I think part of the problem is that the stepper motor that does the extrusion is overheating a little. MIT Swapfest was also this past weekend, and I got a number of small useful items, like a few of these fans for $1 each (including the finger guard). these fans are LOUD and move a lot of air.   One thing that I liked about the fans is that they are the four wire variety which means they can have speed controlled with a PWM signal applied to the blue wire. The base frequency is around 25 kHz, and the duty cycle controls speed (from 30% to 100%). I did a bit of research online, and came across a neat ieda for […]

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