Voltage Comparator with negative signal inputs

[hery]

hi every one,

i wanna make PWM signals by comparing the triangular negative signal and negative sine wave signal as its inputs.

i use LM311 as comparator. i have simulated in proteus, but its doesn't work well.

here i attach the circuit

 

[ericgibbs]

hi,
On your Sim you show that pin7, Col out is used as the signal out.

You should have pin1 Emitter out connected to -Vcc, 0V on your circuit.

 

[hery]

thank you eric,
i have try, but the signal inputs are reduced,
maybe it should use double supply so that the LM311 can compare negative signal inputs,,

 

[alec_t]

Try these LM311 connections:- pin1 to 0V (Gnd) and pin 4 to the -12V rail.