Homemade temperature LED display for PC using PIC16F876

Since I started my watercooling prejoect, I have been verry interested in how well it perform,
the only way is to measure all temperatures before and after,
The motherboard temperature sensors is useless unacurate, so I’m using LM50B

temperature LED display
By using this LM50B sensor I get 1 C of real accuracy
I use a PIC16F876 to drive a four two digits LED displays, the PIC16 has 4 analog inputs with 10 bits resolution,
now I can display 4 temperatures at the same time to monitor performance 🙂
I monitor CPU, Chipset, GFX card, Harddisks.

Here is the schematic good old handdrawn original..
Here is the schematic Re-Drawn Maybe you like this better 🙂 OK, comments for the circuit:
You can use any number of LED displays: 2, 4, 6, or all 8, depending on how many temperatures you want to display,
LED display type must me common cathode, FET can be any N-FET type you have, I have used IRF530 I had on stock,
NPN transistors can also be used if you dont have fets, then remember to mount a 1k resistor on each base inpus.
Each sensor input connector is protected using a 1k resistor, so you can connect sensors with power on,
nothing will burn if you connect it wrong.
Only calibration requred is the refference voltage, it need to be exactly 2.5600 volt, I have used a super stable regulator,
but an LM317 can also be used to make 2.56 volt with if that is what you have. DOWNLOAD The HEX file for the PIC16F876.
The 5 volt supply is taken from a free harddrive power connector, no need to regulate it, 4.8 to 5.2 will work fine.
This complete circuit with 8 all digits consume about 100mA. Good Luck.


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