Hi there,
Where my voltage should be equal to the power supply voltage on the IC1 unit I am getting a voltage about .4V lower than supply voltage. This is testing with the chips installed. Is this wrong or should I expect a slightly lower reading at this point?
Thanks
John
IC1 Voltage problem?
Moderators: JeffC, rdoherty, stieg, brentp
Assuming you mean the
Assuming you mean the ULN2003 darlington array, pin 9 should be about 0.6v lower than the input voltage (about 9v if you're using a PP3 battery, or 12-14v if you're using a car battery) to the unit, so you're just about right...
...the reason is the D2 diode which protects the MJLJ against reverse polarity supply connections - it drops about 0.6v across itself, making the internal "SAFE12V" (see circuit diagram), which is connected to pin 9 of IC1, to about 0.6v less than the supply voltage
...the reason is the D2 diode which protects the MJLJ against reverse polarity supply connections - it drops about 0.6v across itself, making the internal "SAFE12V" (see circuit diagram), which is connected to pin 9 of IC1, to about 0.6v less than the supply voltage
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goldminijohn
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That's the one I meant.
That's the one I meant. Thanks, I got a bit worried on final test when I found that.
John
John