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FET relay configuration

T

tempus fugit

Jan 1, 1970
0
Hey all;

This is kind of picked up from the 'can I do this with a uProcessor' thread.
Eeyore got talking about using JFETs as a replacement for relays. This is
what I've come up with, but I'd be glad to know of a better way, since I
have 4 effects to switch in and out of the signal path, thus putting a fair
amount of noise and resistance in the path:










bypass comp bypass flanger
in
o-----------------o----------------o ---------oo-------------o
| | | | |
|-+ |-+ | |-+ |-+
| | | | |
o ->|-+ o->|-+ | o->|-+ o->|-+
| | | | | | | | |
etc
| | | o | | o | o
| | | | | | | | |
| |-----------|----o---| | o--------|----o
| | | |
| | | |
| | | |
| | | |
| | | |
|
___________ ___________
control v control v control v control v



What do you think? There would be 2 more sets of 2 FETs for the remaining
effects.

Thanks



















(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)
 
D

D from BC

Jan 1, 1970
0
Hey all;

This is kind of picked up from the 'can I do this with a uProcessor' thread.
Eeyore got talking about using JFETs as a replacement for relays. This is
what I've come up with, but I'd be glad to know of a better way, since I
have 4 effects to switch in and out of the signal path, thus putting a fair
amount of noise and resistance in the path:
bypass comp bypass flanger
in
o-----------------o----------------o ---------oo-------------o
| | | | |
|-+ |-+ | |-+ |-+
| | | | |
o ->|-+ o->|-+ | o->|-+ o->|-+
| | | | | | | | |
etc
| | | o | | o | o
| | | | | | | | |
| |-----------|----o---| | o--------|----o
| | | |
| | | |
| | | |
| | | |
| | | |
|
___________ ___________
control v control v control v control v



What do you think? There would be 2 more sets of 2 FETs for the remaining
effects.

Thanks
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

Ohhhhh the horror! :p

Is that some sort of analog multiplexer?
I think the only good application I've had for JFETS is for DC current
sources..

Maybe go mixer style with VCA's...


D from BC
 
W

whit3rd

Jan 1, 1970
0
Is that some sort of analog multiplexer?

... Maybe go mixer style with VCA's...

Probably the intention is to make a clickless switch (by filtering the
control voltage signals). Yep, VCAs or transconductance
amplifiers, like LM13700 and the late SSM2017, are the slick way
to do this.

Or CA3080; I see that's now obsolete. Pity, there were some nice
uses for 'em. The newer designs (LT1228) seem like overperformers,
far pricier and faster than I like.
 
M

Marra

Jan 1, 1970
0
Hey all;

This is kind of picked up from the 'can I do this with a uProcessor' thread.
Eeyore got talking about using JFETs as a replacement for relays. This is
what I've come up with, but I'd be glad to know of a better way, since I
have 4 effects to switch in and out of the signal path, thus putting a fair
amount of noise and resistance in the path:

bypass comp bypass flanger
in
o-----------------o----------------o ---------oo-------------o
| | | | |
|-+ |-+ | |-+ |-+
| | | | |
o ->|-+ o->|-+ | o->|-+ o->|-+
| | | | | | | | |
etc
| | | o | | o | o
| | | | | | | | |
| |-----------|----o---| | o--------|----o
| | | |
| | | |
| | | |
| | | |
| | | |
|
___________ ___________
control v control v control v control v

What do you think? There would be 2 more sets of 2 FETs for the remaining
effects.

Thanks

(created by AACircuit v1.28.6 beta 04/19/05www.tech-chat.de)

Why not use the bog standard 4016 or 4066 bi-lateral switches?
Cheap as chips !

www.ckp-railways.talktalk.net/pcbcad21.htm
 
D

D from BC

Jan 1, 1970
0
Probably the intention is to make a clickless switch (by filtering the
control voltage signals). Yep, VCAs or transconductance
amplifiers, like LM13700 and the late SSM2017, are the slick way
to do this.

Or CA3080; I see that's now obsolete. Pity, there were some nice
uses for 'em. The newer designs (LT1228) seem like overperformers,
far pricier and faster than I like.

Long ago I heard of THAT Corp. VCA's..
D from BC
 
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