This circuit board was sent to me from the seller isaactheodore on eBay. I had purchased some circuit boards from him previously, and showed him that I enjoyed taking electronics apart and photographing the silicon chips inside. He showed me this interesting board that he had and asked if I wanted to open it. Of course I said yes!
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This is the Sample and Hold circuit board from an HP 5180A, which is a Digitizing Waveform Recorder. Their function is to capture analog waveforms on their inputs and convert them into digital waveforms that can be stored in memory. These waveforms could then be displayed on an external monitor. The HP5180A was capable of sampling at a rate of 20MHz, or 1 sample every 50ns.
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Here is an excerpt from the Hewlett Packard Journal November 1982 edition describing how the Sample and hold circuit worked. You can also click the link to the PDF below and read the entire document.
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“The S/H is directed to acquire a point on the S/H input waveform by a positive pulse on the sample line. This pulse forces the sampling switch to close, causing the hold capacitor to charge to the voltage at the input to the switch and then follow or track it. This voltage is a buffered attenuated version of the S/H input. When the pulse returns low, the switch opens and the voltage on the capacitor is held because of the high impedance at this node. The post-amplifier buffers the hold capacitor voltage from the digitizer and amplifies it by a factor of two to compensate for the resistive attenuator at the preamplifier output. The function of the attenuator will be explained later.” - Hewlett Packard Journal, November 1982 Volume
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The above document also mentions that four custom ICs were designed specifically for this circuit. Three of them can be viewed in this video, along with all of the other support chips that are on the hybrid ceramic circuit board.
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There are more things that I’d like to look at in the HP 5180A. If anyone happens to have one that they are looking to part with, even if it's broken, I’d definitely be interested in taking it off your hands. 😁
Video Chapters:
0:00 - Unboxing & Inspection
3:09 - Opening the device
4:20 - First Look
5:22 - Chips under the microscope
References used in video:
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Link to Hewlett Packard Journal PDF:
hparchive.com/Journals/HPJ-198...
All Journals:
hparchive.com/hp_journals
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HP Memory Project link (photo)
www.hpmemoryproject.org/wc_pa...
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Негізгі бет Ғылым және технология HP 5180A Digitizing Waveform Recorder Sample and Hold Circuit board
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