Hello everyone!
I thought that a channel selector would be a great addition to my preamp. The first thing I considered was a mechanical rotary switch. But it would be kind of awkward to use and very unpleasant aesthetically.
Now I'm thinking of a solid state logic circuit along with some switch like TDA1029 or CD4066. Something like this:
http://www.javed007.co.uk/007/New circuit page/Stereo Channel Selector.htm
With the only exception that I'de like to have four buttons instead of one, one for each input. The problem is that I can't find such circuit and my personal skills at triggers and similar stuff are very modest.
If anyone of you has such a circuit or can help in any other way, I'd very appreciate that.
Thank you in advance.
I thought that a channel selector would be a great addition to my preamp. The first thing I considered was a mechanical rotary switch. But it would be kind of awkward to use and very unpleasant aesthetically.
Now I'm thinking of a solid state logic circuit along with some switch like TDA1029 or CD4066. Something like this:
http://www.javed007.co.uk/007/New circuit page/Stereo Channel Selector.htm
With the only exception that I'de like to have four buttons instead of one, one for each input. The problem is that I can't find such circuit and my personal skills at triggers and similar stuff are very modest.
If anyone of you has such a circuit or can help in any other way, I'd very appreciate that.
Thank you in advance.
Hi,
For selectiion logic, the 74c922 keyboard encoder is simple and effective.
It's output is in BCD, so you'll need a binary to decimal (or octal) decoder chip.
This will give you a logic level for each button. You can use this to drive relays or analogue switches for the signal selection.
edit: Not BCD but 4 bit binary
You'll only need the lower 2 bits.
For selectiion logic, the 74c922 keyboard encoder is simple and effective.
It's output is in BCD, so you'll need a binary to decimal (or octal) decoder chip.
This will give you a logic level for each button. You can use this to drive relays or analogue switches for the signal selection.
edit: Not BCD but 4 bit binary
You'll only need the lower 2 bits.
Th '922 has a latch which stores this.
It also has a DAV (data available) signal which I've used before as a mute, for totally silent switching.
Yes it's a bit wasteful using only 3 or 4 out of 16, but it's such an easy chip to use.
There are lots of other solutions. If you wait a few days, others will post their ideas.
Moamps elegant solution again
For switching. relays provide lowest distortion.
For analogue switches, do not consider the 4066. It's decades old and a poor performer.
A cheap, good analogue switch is the DG211 or DG212. The final performance depends a lot on how you use it. I'll post a schematic tomorrow if you are interested.
Or maybe Moamps has a better idea
For switching. relays provide lowest distortion.
For analogue switches, do not consider the 4066. It's decades old and a poor performer.
A cheap, good analogue switch is the DG211 or DG212. The final performance depends a lot on how you use it. I'll post a schematic tomorrow if you are interested.
Or maybe Moamps has a better idea
I started building a channel selector for 2 to 8 inputs, switched by relays and controlled with rotary encoder. The number of channels to choose between is user programmable, last channel is remebered when shut down, and on power up there is a delay. Its based on my relay volume control. I need more relays to build one. The software should allready work.
http://home.tu-clausthal.de/~tpa/selector/index.html
http://home.tu-clausthal.de/~tpa/selector/index.html
dhaen said:
I use reed relays; not the best solution but noiseless (high quality standard audio relays are too expensive for me).
I don't like analogue switches. I agree with you; CMOS are the worst (high R, small headroom,..), DG and MUX are good but not so good as relays. I saw also switches with FETs (J111,etc) but didn't try.
Regards
Thank you all for your ideas. I think I'll go with moamps design. Yes, the cd4066 is rather old and noisy, but the other switches you've mentioned are hard to get and/or expensive here. Any other ideas about switching? Maybe another chip? How about tda1029? It has everything one could need, not sure about noise though.
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