I need a simple little voltage monitoring circuit

Jul 21, 2004 1 Replies

Hi folks,



I've got four voltages:



28 VDC, 24 VDC, +15 VDC, -15 VDC I want an LED to illuminate when all four voltages are "good". Can someone recommend come IC chips I could wire up to achieve this. I don't care what the tolerances for "good" are, 10%, 50%, whatever, anything reasonable is fine. I need to built a little 4" square circuit board or whatever size fits it. Thanks in advance for ideas!

Gary


The classic circuit for this function was the famous 339 IC. Newer designs from companies such as Maxim can also perform multiple voltage monitoring. BTW, what is good? When voltage is beyond a certain level relative to zero? When a voltage is below a certain level? When ripple volts is below certain criteria. There alone are three separate things you might have to monitor for each voltage. Then you must decide whether you want to latch on failure OR just indicate when failure occurs for long periods of time - long enough to even extinguish the indicator lamp.

First def> Hi folks,

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