Hi everyone, I have built a circuit with a PIC micro-controller (16F877A). I have connected +5 V supply to the MCLR pin through a resistor of 4.7 kΩ. All I saw in sample designs were 4.7 kΩ or 10 kΩ but my circuit doesn't work. When I measure the potential difference between the ground and the MCLR pin I read a 4.40 V value. I have two questions now. 1) Do I have to use a smaller resistor? 2) Why all the sample designs with 4.7 kΩ are OK and mine is not? What can I be missing? What may cause this huge potential drop (About 0.70 V)? Some additional information found by mistake: 1) Once the PIC didn't fit to the socket well and the MCLR pin was not plugged in. When I measure the potential difference, it was about 5 V. 2) While I was trying to measure current I put one of the probes on MCLR and the other one to the OSC1/CLKIN by mistake (It is a multimeter with two probes) the circuit worked. With the help of the additional information could you please comment on what my problem can be?