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John, the input load is the 1K resistor. When used as an amplifier, the input of an OPAMP is ZERO ohms. The feedback resistor guarantees this when the amplifier is running in the linear range.I have used CT's in a number of commercial device designs. Usually, the CT is defined by an input to output current ratio. The CT will always try to output the current ratio, so a load should always be across the CT.In this case, as long as the OPAMP is powered up, there is no problem. However, if the system is powered down the voltage developed across the CT's leads could be large enough to kill the opamp. A better idea would be to put a 500R resistor or 2 zener diodes across the CT output to limit the voltage developed.
Great job. Your controller looks like it will perform much better than the Weller that I have, and it does a pretty good job. Yours I think will provide better control. Also, I am glad that you got rid of the DIN connector for the probe. These are a problem after a few years. I have changed all of mine to XLR connectors, but your connector will work just as well and for less money. Keep up the great work.
A nice refinement would be automatic shutoff after 30 minutes of so (maybe adjustable) of non-use. I have a Hakko without this, and a Weller with this feature. It can save a lot of tips from failing due to forgetting to turn off your iron. I have a large, crowded work space and it is difficult to turn everything off whern I pack up for the evening, day, whatever. Just a thought, and a very nice instructable.
Hi,Weller, I think, monitors the tip temperature for a deep dip which is caused by the iron being put to use and thus requiring more power to get the tip up to temperature. Just a few degrees of a drop should be more than sufficient. I am a hardware guy, not software although I have been known to write some BASIC code, and it would seem to me that it would be reasonably simple to add this. Your followers will love you if you, or one of them can implement this feature.All in all, this is a terrific Instructable. Keep up the good work!!!
There was an article similar to this in Popular Electronics in the late 60's or early 70's. It was all analog, used a wheatstone bridge (if I remember correctly) and H-bridges to drive the motors. Super simple and reliable. The sensors were photocells on a flat board with two pieces of PCB shielding each photocell from the others. The idea was that when the sun was fully illuminating all the photocells, the system would stop moving. It worked well and was simple following the KISS engineering principle. I am surprised at how complicated things have become to do simple things in the last few years!Don't get me wrong, I think this project is terrific.
Hi Canyonman,You could adapt this to track satellites as the concept is the same, however the detection of the satellite and keep it centered would be difficult. You might want to look up radiosonde equipment to do this. I worked on one system many years ago that would follow radiosonde balloons for miles. The concept is the same, just different.
Breathe New Life into an Old Computer
Nature Nanotechnology reports this DIY AFM (Atomic Force Microscope) / 自己動手做原子力顯微鏡 and DIY AFM controller get hacked
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