| Products > Test Equipment |
| Replacement for Fluke 700013 IC (quad SPST analog switch) |
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| richipedia:
I cobbled together a simple test interface to be controlled by a RasPi. It helped my to get my understanding of the workings of the 700013 right and to see which of my ICs are broken. The RasPi provides the logic control signals. The outputs are connected to just a bunch of resistor dividers, so see if the analog switches can be enabled and disabled. This is basically a DC test, though, not taking care of digital timing or any of the properties I mentioned in my initial post. |
| richipedia:
Just to feed your interest, here's prototype 0 on a breadboard (while it's in the making), shoved into my test adapter. :) |
| richipedia:
Prototype 0 was already built to fit into the original PCB, so that's what I did. With the 8842's PCB populated my working 700013 ICs and the prototype in the right places for the right measuring mode, it kind of works. |
| richipedia:
For some reason, I built prototype 1 on veroboard. It plugs nicely into the 8842. |
| richipedia:
The 8842 has 5 700013 ICs. There is one IC in my unit which I believe is fully functional. The remaining 4 are somewhere between "suspiciously high current consumption/input loading" and "completely dead". I didn't quite like the idea of making a total of 5 hand-wired veroboard replacements, so I ordered some PCBs. Eagle files are attached. I tried to recreate the solder mask keep-outs I found on the 8842 PCB on my PCBs, although I am not completely aware of what I am doing here and how to get it right :-// With U301, U302 and U303 populated with my replacement PCB and using two of the original 700013 for U402 and U403, the DMM kind of works. I tried calibrating it at work. * Some of the higher VDC ranges did calibrate correctly. Success! :box: * Some of the lower VDC ranges did not calibrate. Probably it was the 20mV and the 200mV ranges, but would have to check again to be sure. * Most Ohms ranges did not calibrate correctly. * The ADC ranges did calibrate correctly. Yay! :box: |
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