Solid construction, elegant design and high precision production. Once upon a time, Hewlett Packard Testing and measurement tools that were dear to the working engineers. Sure, leave one of those infants on your foot and you were watching a broken toe. But this is a small price to pay for reliability and some character building. So when I recently came to the HP 7041A XY recorder in the early 1970s, while I cleaned my parents’ attic, I knew that I just had to see if I can get it and run again.
What is the difference between a XY recorder and a plotter?
XY recorder Unlike the plotter, in real time, the data was designed to chart data from analog instruments, which plots the output of the digital computer. Basics are the same: a mechanism to lift and reduce a pen, and motors to move the pen on a page surface. The big difference is that a plotter usually uses a digital command to control the speed of the pen, while the speed of a recorder’s pen is controlled by analog voltage input.
So I just needed to do that the HP recorder had to feed the right voltage, and I could attract what I wanted! Only a few obstacles were standing in my way.
The recorder interface allows the python code written on a raspberry pie (bottom right) to create analog signal that is transferred up and down to the level to complete the various categories required by the Plotter’s X-and Y-Axis. James provost
The first hurdle house was getting the house, because my parents’ attic was in Ireland and 13 kg, 48-by-36-by-17-seven meter beamoth was returning to my flight in my suitcase, which was not returning to NYC. About 300 US dollars in packing materials and shipping fees solve that problem, and I was still slightly ahead of the game compared to getting a similar vintage recorder from eBay, and the way before buying a new Banom tool Nextdro plotter With a similar drawing area. (To be fair for the bantam, its plotter is sleek plug-and-play devices that can handle a very wide range of pen).
The second obstacle was that the recorder did not work. Once I took it home, I came to know that y-Xis can be adjusted manually using a knob on the control room, but X-Axis was dead. The mechanism of lifting and reducing the pen created a weak clinking sound and barely added to the twisted.
“Did I spend a lot of money to send just an HP-model boat anchor home?”
I opened the case, which was a quick task with a Philips screwdriver – no strange safety screws, no glue, no delicate plastic, no yellow sticker warns that your warranty will be zero and if you dare to look inside you will probably be boiled. On the beautifully printed circuit boards inside, I saw some resistance that were not clearly part of the factory install. Was they amendment or repair? If the latter, were they successful or did I spend a lot of money to send just an HP-model boat anchor home? And I did not know how the 40-Pin interface connector behind the recorder should have been tilted to control the signals.
All these problems were solved when I found a recorder manual on eBay. Oh, what a manual. Not only the operation instructions, but also to completely separate the recorder and keep it back together. It lists every component, photos of circuit boards and electronic skimatics on gatefolds. And this included the direction -guidelines to modify the circuitry if you wanted to measure various voltage range compared to the factory settings – remove a inhibitor Here And There And mix in some new people. This explained the resistance I saw. In a world where licenses and software forbids people to plug into only one replacement component, thought of a major company that encourages its customers to break a soldering iron, it is in the grip of the mind.
Soon, some application Instrumental oil, Silicon greeceAnd Kimwips Was X-Axis and pen lifters are working again. I tilted a variable power supply for the connector of the recorder and slowly Bring the voltage up as I saw the pen holder in response. This allowed me to determine the input range of the recorder, which left for 0 to 1 volt y-Axis, and 0 to 5th X-Xis, covering 25 and 38 cm speed respectively, with about 0.2 mm accuracy.
The next step was to build an interface. Although microcontrollers often have digital-to-analog capabilities, often only a true analog output pin. I needed two. Like a technique pulse width modulation Lets me output an analog on several pin, but usually with Only 8-bit resolution Or 256 separate voltage levels. I needed at least 1,900 levels to match the accuracy of the recorder.
The raspberry pie uses an expansion “hat” and two 12-bit digital-to-analog converters that have been commanded to create a 3.3-volt control signals through I2C connectors. These are transferred from 0– V and 0- to 5-V range using voltage dividers and amplifiers respectively, as well as a logic gate used to change the 3.3-V digital signal that increases and reduces the pen to 5-V levels.James provost
So i bought two $ 5 adafruit Mcp4725 breakout boardThese 12-bit digital-to-analog converters are-each provides 4,096 different levels-controlled on one. I2C serial Connection, and two boards can share the same I2C bus. I associated them with A Raspberry Pie Model B+ I get out of a drawer via $ 6.60 Sparkfun Quvic Hat,
DACS gave an indication in the range of 0 to 3.3 V, so I sent a board output through one Voltage divider To scale it from 0 to 1 V y-Axis. For X-Axis, I fed other board output through one LMC6484 Amplifier, powered by a 5-V pin from PI, does not have a full range to bring it from 0 to 4.8 V, but will do it until I come with a more sophisticated interface. I brought a signal to the pen to lift and reduce the pen, which comes out of the PI’s GPIO PIN, passes it through one 74LS08 and Gate IC A cheap and cheap 3.3- to 5-V is used as a digital level shifter.
I then wrote the code on the PI, in which the Plotter was written through its pace, using parametric equations written. Circuitpithon Wandering Hypotrokeoids And other geometric curves. Ultimately, it should be possible to accept the PI and translate commands written in a plotter-control language. Hp-gLThen I will be able to plot vector graphics and text with drawing software InkscapeBut for now, I am happy that my recorder should be hummed next to me, hail and made to heart and last.
From your site articles
Related articles around web
