Problem with PIC16F87

[The Master]

Thats another mistake, sorry. There is a 10K resistor between pin 3 on the 555 and the base of the transistor.

I use 7805s in every circuit i make that needs 5V and they never need a heatsink. Sometimes they do get slightly warm if a lot of things are running from them but still not enough to need a heatsink.

For testing i moved the 555 to a breadboard with a seprerate regulator and that regulator stayed cold. The one on the main board still got hot though which means its the IR emitters that are causing it to overheat. According to the datasheet they should be drawing 100mA each. Theres 2 of them but its about a 50% duty cycle so i would expect the average to be around 100mA. Lastnight my multimeter showed 102mA for the emitters and the 555 so i guess thats about right then as long as i put a heatsink on this regulator.

[dhouston]

I see Data A & Data B but no GND for the RS485 network.

[The Master]

The RS485 ground is the same as the ground for the rest of the circuit (0V)

[dhouston]

Try it with the RS485 network disconnected. If the current drops, then use a 100 ohm, 1/4W resistor between the RS485 GND and this circuit's GND.

[The Master]

The RS485 chip hasnt been plugged in most of the time

[dhouston]

The RS485 chip hasnt been plugged in most of the time

You could still be drawing a lot of current due to mixing grounds. Try it with the network disconnected, including its GND.

[The Master]

For most of this testing the RS485 chip hasnt been plugged in and the data wires disconnected. When it has been connected up the RS232 to RS485 convertor has been running from the same power supply.

Im pretty sure theres no problem with the RS485 part of the circuit. When the chip starts having a fit during pause commands if i pull the 555 out then it suddenly goes back to normal.

I also tried using the 555 on the breadboard but removing its regulator and connecting the power wires after the regulator on the PCB and that causes problems aswell. It only works when the 555 and PIC have different regulators