Doing the ciruit suggested below, I was able to set 0.8 volts on the Vref. Currently my output is about 4.8 volts when the Vin > Vref. How can I get the HIGH output when Vref > Vin instead?
+----------+---+5V | | [100k] | | | +---------|+\\ | | >--[--|---------|-/ | | [50k]You already have HIGH when VRef > Vin. If you want the inverse VRef < Vin, then swap + and - pins of the circuit. I hope this helps.
Bill
On Fri, 10 Feb 2006 07:53:56 -0500, Manimozhi Baskaran wrote:
--- You're doing something wrong.
With the signal on the - input more positive than the signal on the
Conversely, with the + input more positive than the - input, the output should be close to +5V.
BTW, if you want to see the circuit working, simulate it.
Go to:
Download their wonderful free simulator and run this:
Version 4 SHEET 1 880 680 WIRE -416 384 -416 224 WIRE -416 544 -416 464 WIRE -304 384 -304 -32 WIRE -304 544 -416 544 WIRE -304 544 -304 464 WIRE -144 -32 -304 -32 WIRE -144 0 -144 -32 WIRE -144 256 -144 80 WIRE -144 384 -144 256 WIRE -144 544 -304 544 WIRE -144 544 -144 464 WIRE -80 224 -416 224 WIRE -80 256 -144 256 WIRE -48 -32 -144 -32 WIRE -48 208 -48 -32 WIRE -48 544 -144 544 WIRE -48 544 -48 272 WIRE 32 240 -16 240 WIRE 112 240 96 240 WIRE 112 240 112 224 WIRE 112 352 112 240 WIRE 112 416 112 352 WIRE 112 544 -48 544 WIRE 112 544 112 480 WIRE 240 -32 -48 -32 WIRE 240 0 240 -32 WIRE 240 128 240 80 WIRE 240 256 240 128 WIRE 240 400 240 256 WIRE 240 544 112 544 WIRE 240 544 240 480 WIRE 288 128 240 128 WIRE 288 352 112 352 WIRE 400 224 112 224 WIRE 400 256 240 256 WIRE 432 -32 240 -32 WIRE 432 208 432 -32 WIRE 432 544 240 544 WIRE 432 544 432 272 WIRE 528 128 368 128 WIRE 528 240 464 240 WIRE 528 240 528 128 WIRE 528 352 368 352 WIRE 528 352 528 240 WIRE 528 416 528 352 WIRE 528 544 432 544 WIRE 528 544 528 496 WIRE 528 608 528 544 FLAG 528 608 0 SYMBOL res -160 -16 R0 SYMATTR InstName R1 SYMATTR Value 100k SYMBOL res -160 368 R0 SYMATTR InstName R2 SYMATTR Value 19k SYMBOL voltage -304 368 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V1 SYMATTR Value 5 SYMBOL voltage -416 368 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 WINDOW 3 24 104 Invisible 0 SYMATTR InstName V2 SYMATTR Value PULSE(+5 0 0 1 0 1 1 1) SYMBOL res 224 -16 R0 WINDOW 0 -52 37 Left 0 WINDOW 3 -48 67 Left 0 SYMATTR InstName R3 SYMATTR Value 100k SYMBOL res 224 384 R0 WINDOW 0 58 40 Left 0 WINDOW 3 64 69 Left 0 SYMATTR InstName R4 SYMATTR Value 100k SYMBOL diode 96 224 R90 WINDOW 0 -51 32 VBottom 0 WINDOW 3 -41 34 VTop 0 SYMATTR InstName D1 SYMATTR Value 1N914 SYMBOL res 384 112 R90 WINDOW 0 -43 57 VBottom 0 WINDOW 3 -32 60 VTop 0 SYMATTR InstName R5 SYMATTR Value 22k SYMBOL res 384 336 R90 WINDOW 0 -36 61 VBottom 0 WINDOW 3 -32 67 VTop 0 SYMATTR InstName R6 SYMATTR Value 100k SYMBOL cap 96 416 R0 SYMATTR InstName C1 SYMATTR Value .2e-6 SYMBOL res 512 400 R0 SYMATTR InstName R7 SYMATTR Value 10k SYMBOL Opamps\\\\LT1013 -48 176 R0 SYMATTR InstName U1 SYMBOL Opamps\\\\LT1013 432 176 R0 SYMATTR InstName U2 TEXT -450 554 Left 0 !.tran 1
I've substituted LT1013's for the LM324's, but that shouldn't make any real difference in whether the thing runs or not.
-- John Fields Professional Circuit Designer
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.