Bench Power Supply w/ HC4LED
John Couture
Posts: 370
Hey all,
My goal (not a·contest project) is to build a nifty Bench Power Supply using an old Desktop PC power supply, an SX·and three of Bean's HC4LED displays (these are kool!) to show acutal 12vdc, 5vdc and amps.·
I think I understand the concept of how to measure the voltage but how do I measure the amps (say up to 5 amps) and supply that info to the SX so that it can update the digital displays and a send the status out a serial port?· I need something like a "shunt" but how do I get the info into the SX?
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John J. Couture
San Diego Miramar College
My goal (not a·contest project) is to build a nifty Bench Power Supply using an old Desktop PC power supply, an SX·and three of Bean's HC4LED displays (these are kool!) to show acutal 12vdc, 5vdc and amps.·
I think I understand the concept of how to measure the voltage but how do I measure the amps (say up to 5 amps) and supply that info to the SX so that it can update the digital displays and a send the status out a serial port?· I need something like a "shunt" but how do I get the info into the SX?
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John J. Couture
San Diego Miramar College
Comments
There are dedicated current measurement chips. Or else you need a shunt, and an A to D converter.
Here is a tutorial from Maxim http://www.maxim-ic.com/appnotes.cfm/appnote_number/746/
Bean.
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Cheap used 4-digit LED display with driver IC·www.hc4led.com
Low power SD Data Logger www.sddatalogger.com
SX-Video Display Modules www.sxvm.com
"People who are willing to trade their freedom for·security deserve neither and will lose both." Benjamin Franklin
Post Edited (Bean (Hitt Consulting)) : 10/29/2006 2:45:15 AM GMT
The set up is similar to what is done on the Propeller, just a capacitor and a few resistors.
A dedicated current chip may get you into a similar tangle of code. It all depends on how 'programmible' the device is. I suspect you still need a shunt resistor either way.
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"If you want more fiber, eat the package.· Not enough?· Eat the manual."········
Great to see you have embraced the Virtual A/D approach.
That said, the DS2760 chip used in the Parallax Thermocouple kit, has an internal 25 milliOhm current sense risisor as well as a 12 bit A/D
Cheers,
Peter (pjv)