I have a bunch of x y flatbed recorders and I want a simple rising volatge to simulate passing time on the x axes. I can work from a diagram and know some basics. HP made this in a small package.... HP
17108A.... anybody have one? I can take MV or volts 1-10.
You could keep it simple by using an LM334 constant current IC (3 pin device) by National and discharge it into a capacitor. You can tweak the current on the LM334 with a pot, and make a nice linear ramp. This is a 3 part solution, not including any power supply.
Dual 12-bit voltage-output DACs. One of the few with such a peripheral, but rather slow and power-hungry.
Best regards, Spehro Pefhany
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"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
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4 DACs with a nice 45MHz ARM core and only 6mm x 6mm.
;-)
Best regards, Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
Thanks everybody, most of you are over my head. I would like at least one hour at one shot. I would like a diagram,( I could build heath kits) I'm not in the electronics trade.
Use a binary counter with appropriate weighted summing resistors connected to the outputs Adjusting the clock rate into the counter determines the rate of rise. The number of stages in the counter determines the resolution.
2 Use a microcontroller with an analog output such as Analog Devices ADUC812 see
formatting link
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The capacitor size depends on how fast you want to sweep and which range of the recorder you're on. Try 10 microfarads to start, 1 volt range maybe. Stay at 1 volt range or preferably less, otherwise the sweep will get nonlinear.
Open the switch to run the ramp.
Ignore all the complicated electronics suggestions.
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I love to cook with wine. Sometimes I even put it in the food.
For one hour, you'll probably do best with a CMOS 555 feeding a
74HC4040 feeding a R-2R ladder network. Maybe someone feels like drawing it up.
Best regards, Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
How fast will that 0.010 F electrolytic self-discharge? The tolerance will not be so nice either.
I see a lot of +80%/-20% with the double-layer capacitors. A mechanical clock and a pot would be much more accurate. The error is all due to the nonlinearity of the pot, and that doesn't accumulate. Or use a PIC.
Or a DAC08, or two of them for more precision. These should be found in the bins of any decent lab and would save a lot of resistor matching and soldering.
If you are in a lab look around whether one of the function generators allows for really long timing. Sometimes they will indicate in "milli-Hertz", sometimes as period times. Only digitally controlled ones will be able to do that. That way you may not have to build anything.
Will this be running off the line? Maybe two opamps and an 6-bit counter at the core...Do you know enough to build a small DC power supply, or any other construction techniques?
The flatbed is line voltage. I can build but not design. Can do vdc. Is a discharging cap more linear? I can run my flat bed x axis backwards if this helps.
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