Circular chart recorders...

[Externet]

Hello all.
Never canibalized one, and now am trying to see if one of those would work for a project.
Do they exist for one year per revolution?
Is their mechanism similar to a plain single cell driven clock ?

Does anyone has a suggestion for a less than 13V DC operated mechanism that will turn one revolution per 24 hours and also gearing for another included wheel on one year per revolution ?

Alternatives in mind are using a ~$20 atomic clock and tapping (if I can) every minute pulse to step a stepper motor, and a ÷7 pulse counter every time hits a (calendar) day of the week, as to step 1/52nd of a turn to make the year.

In other words, am looking for a mechanism that will yield both 1 daily and 1 yearly turn wheels, capable of nearly 1 inchpound torque.
Miguel

[Chris Smith]

If you want to build one cheap, use a military clock that turns once per 24 hours, not every 12 hours. Either one can work but the chart is easier to read.

If you make a light weight disk for the hour arm and cover it with paper then use another stepper motor or gear motor to move an armature a few thou every 24 hours.

Attach a pencil on the arm and start to chart.

You can find clocks that run off 1.5 volts and up.

You can also make a drum instead [seismic drums] and drive the whole thing the same way which is easier to build and make steady with tiny bearings.

[haklesup]

Mechanical chart recorders are way old school. Now a days we use flash memory backed DAQ systems. For temperature and pressure there are many options and some with LiIon batteries will last over a year and can be programmed for any acquisition rate.

I've never seen a 1 year chart recorder but since there are 365 days in a year, you would need a gear with that ratio to reduce a 24hr/rev to 8760hr/rev. Certainly possible just never seen one, it may be impractical WRT the pen lasting that long though. This is 50s-80s vintage stuff afterall.

Your plan for steppers is sound but you need to ensure there will never be a false step due to noise.

[Chris Smith]

Paper chart recorders are not just the 1950s.

They are still used today with 100% reliability and are required for many sensitive pieces of equipment.

USGS still records all the seismic recordings on paper drums as do other organizations for a good reason, they work.

Yes bulky, yes old, yes reliable and easy to read with lots of moving parts which so far hasent let us down. No one really needs any fancy stuff to tell us the color of the sky.

Small electronics are great for space saving, no moving parts, etc., however that isn’t always a requirement in the real world.

Chart recorders is an art form that isn’t about to go away any time soon.

[Smoke_Maker]

You mean like these,

http://www.candhsales.biz/cgi-bin/shop9 ... htm#CR8401

[rshayes]

Omega Engineering (www.omega.com) still sells circular chart recorders.

The current practice seems to be using a stepper motor to drive the chart. This allows the speed to be changed by changing a digital divider. The classic chart recorders used gears, so changing the chart speed meant changing the gears in a gear train.

The Omega recorders seem to go up to a seven day range. They are also fairly expensive (about $1000) if bought new.

A stepping motor driven recorder could easily be slowed down to 1 revolution/year by adding a divider to the clock in the stepping motor driver. Most of the time, this would divide by 365, except for leap years.

A stepping motor driven at 1 RPM would have to be geared down with a ratio of 1440 to get 1 revolution per day. With this much reduction, practically any stepping motor should be able to deliver the torque you want.

The older recorders with gear trains might be a problem, since several stages of gear reduction would have to be added to reduce the speed to 1 revolution per year. Alternately, it might be possible to replace the original motor woth a stepping motor. The original motor would probably be a synchronous motor running at 1800 or 3600 RPM. A stepping motor could easily be driven at 1/365 of this speed, so that a motor originally geared for 1 revolution per day would give a chart speed of 1 revolution per year.

[Dave Dixon]

We used to repair these awesome barographs used in gliders. This was a purely mechanical device with a diaphragm, clock mechanism, a stylus, and a cylindrical drum made of metal. Rather than using ink and paper, before use, the user would burn a piece of camphor (wood), and allow the thick smoke to coat a thin strip of aluminum wrapped around the drum. After winding up the clock mechanism, the drum would slowly but accurately rotate while the sharp stylus would swing due to altitude changes, as it was linked to the diaphragm, and "etch" away the carbon coating on the aluminum strip. When finished recording, the aluminum (foillike) strip was layed out flat, and sprayed with laquor to preserve the markings. We certified these to NIST and FAA standards, and they were still in use a few years (okay - maybe 10 or so) to establish official soaring records. I'm sure this won't help you, but I thought I'd pass the information on regardless!
Ah, the good old days. No batteries, no microcontrollers, whoops wrong forum for that kind of talk! Good luck with your project,
Dave
See pictures here...http://www.wingsandwheels.com/page12.htm