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ADC0804 Grounding problem with pin 3 and 5

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muhammad shoaib

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Hi there I am using ADC0804 in test running mode. The circuit is just exactly as below

ADC Problem.png

When I touch pin 3 or 5 my circuit starts working really cool but as soon as I pull my finger away the outputs at D0 - D7 gets Stuck.

Assume all the connections are perfectly fine and on breadboard. Input voltage is exactly 5.01v on the IC

The capacitors are of exact values as shown in the given circuit.
 

the circuit does not look okay.Can the pin be left floating?
There should be a pull up at that point where you touch. Try connecting a 4.7K resistor from that point to VCC.
 

Pin 5 is actually an output (interrupt from adc to mcu). You should not connect it straight to gnd. Better through like 20k resistor to GND. And WR is write strobe, which you have to pull low every time you want to write data to adc. So you should connect it to mcu, not to some fixed potential.
 

Problem solved. Circuit was all right. The problem lied in the fact that the wires in pin were of long length that induced emf in the two wires. As soon as you prepare your circuit on vero board the problem diminishes. :) Anyways thanks buddies
 

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