On Thu, 10 Nov 2011 00:51:03 -0800, DaveC wrote:

Exactly. Much easier than all these halved supplies, coupling caps and
multiple grounds.

d

So, how -- exactly -- would you create that negative voltage?

Dave

---
Here's the whole thing; DC coupled mixer with a charge pump for a
negative supply:


Version 4
SHEET 1 1676 1124
WIRE -32 -528 -64 -528
WIRE 80 -528 48 -528
WIRE -208 -432 -528 -432
WIRE -96 -432 -128 -432
WIRE -64 -432 -64 -528
WIRE -64 -432 -96 -432
WIRE -32 -432 -64 -432
WIRE 80 -416 80 -528
WIRE 80 -416 32 -416
WIRE 112 -416 80 -416
WIRE 320 -416 192 -416
WIRE 464 -416 320 -416
WIRE -32 -400 -64 -400
WIRE 320 -384 320 -416
WIRE 224 -368 176 -368
WIRE -64 -352 -64 -400
WIRE -208 -336 -432 -336
WIRE -96 -336 -96 -432
WIRE -96 -336 -128 -336
WIRE 128 -336 128 -368
WIRE 320 -272 320 -304
WIRE -528 -240 -528 -432
WIRE -416 -240 -528 -240
WIRE -64 -240 -336 -240
WIRE -32 -240 -64 -240
WIRE 80 -240 48 -240
WIRE -432 -192 -432 -336
WIRE -352 -192 -432 -192
WIRE -64 -192 -64 -240
WIRE -64 -192 -272 -192
WIRE -272 -144 -336 -144
WIRE -64 -144 -64 -192
WIRE -64 -144 -192 -144
WIRE -176 -96 -240 -96
WIRE -64 -96 -64 -144
WIRE -64 -96 -96 -96
WIRE -32 -96 -64 -96
WIRE 80 -80 80 -240
WIRE 80 -80 32 -80
WIRE 112 -80 80 -80
WIRE 320 -80 192 -80
WIRE 464 -80 320 -80
WIRE -32 -64 -64 -64
WIRE 320 -48 320 -80
WIRE 224 -32 224 -368
WIRE 224 -32 176 -32
WIRE -64 -16 -64 -64
WIRE 128 0 128 -32
WIRE 320 64 320 32
WIRE -32 96 -64 96
WIRE 80 96 48 96
WIRE -336 192 -336 -144
WIRE -208 192 -336 192
WIRE -96 192 -128 192
WIRE -64 192 -64 96
WIRE -64 192 -96 192
WIRE -32 192 -64 192
WIRE 80 208 80 96
WIRE 80 208 32 208
WIRE 96 208 80 208
WIRE 320 208 176 208
WIRE 464 208 320 208
WIRE -32 224 -64 224
WIRE 320 240 320 208
WIRE 224 256 224 -32
WIRE 224 256 160 256
WIRE -64 272 -64 224
WIRE -240 288 -240 -96
WIRE -208 288 -240 288
WIRE -96 288 -96 192
WIRE -96 288 -128 288
WIRE 112 288 112 256
WIRE 320 352 320 320
WIRE 48 368 -64 368
WIRE 224 368 224 256
WIRE 224 368 128 368
WIRE 224 400 224 368
WIRE 224 496 224 464
WIRE -80 576 -112 576
WIRE -64 576 -64 368
WIRE -64 576 -80 576
WIRE 16 576 -64 576
WIRE 336 576 240 576
WIRE 304 640 240 640
WIRE 16 704 -32 704
WIRE 384 704 240 704
WIRE 464 704 384 704
WIRE 560 704 544 704
WIRE 656 704 624 704
WIRE 672 704 656 704
WIRE 752 704 736 704
WIRE 768 704 752 704
WIRE 384 736 384 704
WIRE 272 768 240 768
WIRE -80 832 -80 576
WIRE 272 832 272 768
WIRE 272 832 -80 832
WIRE 656 848 656 704
WIRE 752 848 752 704
WIRE -528 864 -528 -240
WIRE -432 864 -432 -192
WIRE -336 864 -336 192
WIRE -240 864 -240 288
WIRE -80 864 -80 832
WIRE -32 864 -32 704
WIRE 304 864 304 640
WIRE 304 864 -32 864
WIRE 384 864 384 816
WIRE 384 864 304 864
WIRE 384 896 384 864
WIRE -528 1008 -528 944
WIRE -432 1008 -432 944
WIRE -432 1008 -528 1008
WIRE -336 1008 -336 944
WIRE -336 1008 -432 1008
WIRE -240 1008 -240 944
WIRE -240 1008 -336 1008
WIRE -80 1008 -80 944
WIRE -80 1008 -240 1008
WIRE 336 1008 336 576
WIRE 336 1008 -80 1008
WIRE 384 1008 384 960
WIRE 384 1008 336 1008
WIRE 656 1008 656 912
WIRE 656 1008 384 1008
WIRE 752 1008 752 912
WIRE 752 1008 656 1008
WIRE -528 1104 -528 1008
FLAG -64 272 0
FLAG 0 -448 +16
FLAG 0 -384 -10
FLAG -64 -352 0
FLAG -528 1104 0
FLAG -64 -16 0
FLAG 464 -416 LA+LB
FLAG 464 -80 LA+LB+RA+RB
FLAG 464 208 RA+RB
FLAG 0 -112 +16
FLAG 0 176 +16
FLAG 0 -48 -10
FLAG 0 240 -10
FLAG -112 576 +16
FLAG 768 704 -10
FLAG 128 -336 0
FLAG 128 0 0
FLAG 112 288 0
FLAG 224 496 0
FLAG 320 -272 0
FLAG 320 64 0
FLAG 320 352 0
SYMBOL Opamps\\LT1007 0 144 R0
SYMATTR InstName U1
SYMBOL voltage -240 848 R0
WINDOW 3 24 96 Invisible 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR Value SINE(0 1 1000)
SYMATTR InstName RB
SYMBOL res -112 176 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R1
SYMATTR Value 10k
SYMBOL res -112 272 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R2
SYMATTR Value 10k
SYMBOL res 64 80 R90
WINDOW 0 -35 58 VBottom 2
WINDOW 3 -35 60 VTop 2
SYMATTR InstName R3
SYMATTR Value 10k
SYMBOL Opamps\\LT1007 0 -480 R0
SYMATTR InstName U2
SYMBOL res -112 -448 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R4
SYMATTR Value 10k
SYMBOL res -112 -352 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R5
SYMATTR Value 10k
SYMBOL res 64 -544 R90
WINDOW 0 -38 58 VBottom 2
WINDOW 3 -33 59 VTop 2
SYMATTR InstName R6
SYMATTR Value 10k
SYMBOL res -80 -112 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R7
SYMATTR Value 10k
SYMBOL res -176 -160 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R8
SYMATTR Value 10k
SYMBOL res -256 -208 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R9
SYMATTR Value 10k
SYMBOL res -320 -256 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R10
SYMATTR Value 10k
SYMBOL Opamps\\LT1007 0 -144 R0
SYMATTR InstName U3
SYMBOL res 64 -256 R90
WINDOW 0 -37 62 VBottom 2
WINDOW 3 -37 60 VTop 2
SYMATTR InstName R12
SYMATTR Value 6.2k
SYMBOL voltage -336 848 R0
WINDOW 3 24 96 Invisible 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR Value SINE(0 1 1700)
SYMATTR InstName RA
SYMBOL voltage -432 848 R0
WINDOW 3 24 96 Invisible 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR Value SINE(0 1 2300)
SYMATTR InstName LB
SYMBOL voltage -528 848 R0
WINDOW 3 24 96 Invisible 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR Value SINE(0 1 4260)
SYMATTR InstName LA
SYMBOL Misc\\NE555 128 672 M0
SYMATTR InstName U4
SYMBOL voltage -80 848 M0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V3
SYMATTR Value 16
SYMBOL cap 400 896 M0
WINDOW 0 -19 1 Left 2
WINDOW 3 -21 57 Left 2
SYMATTR InstName C1
SYMATTR Value 1n
SYMBOL diode 736 720 M270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D1
SYMATTR Value 1N4148
SYMBOL diode 672 848 M0
SYMATTR InstName D2
SYMATTR Value 1N4148
SYMBOL polcap 768 848 M0
SYMATTR InstName C2
SYMATTR Value 1µ
SYMBOL polcap 560 688 M90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C3
SYMATTR Value 1µ
SYMBOL res 368 720 R0
SYMATTR InstName R13
SYMATTR Value 10k
SYMBOL res 560 688 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R14
SYMATTR Value 100
SYMBOL sw 96 -416 R270
WINDOW 0 32 15 Left 2
WINDOW 3 32 44 Left 2
SYMATTR InstName S2
SYMBOL sw 96 -80 R270
WINDOW 0 32 15 Left 2
WINDOW 3 32 44 Left 2
SYMATTR InstName S1
SYMBOL sw 80 208 R270
WINDOW 0 32 15 Left 2
WINDOW 3 32 44 Left 2
SYMATTR InstName S3
SYMBOL res 144 352 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R11
SYMATTR Value 10k
SYMBOL cap 208 400 R0
SYMATTR InstName C5
SYMATTR Value 100n
SYMBOL res 304 -400 R0
SYMATTR InstName R15
SYMATTR Value 1000
SYMBOL res 304 -64 R0
SYMATTR InstName R16
SYMATTR Value 1000
SYMBOL res 304 224 R0
SYMATTR InstName R17
SYMATTR Value 1000
TEXT -296 1040 Right 2 !.tran .01 startup uic
TEXT -488 1080 Left 2 !.model SW SW(Ron=1 Roff=10Meg Vt= 8 Vh=0)
--
JF