Do guitar pedals draw guitar signal when there is no amp connected at their output?

SgtWookie

Joined Jul 17, 2007
22,230
You might also consider using an analog multiplexer.
Besides the industry standard 4066, Maxim/Dallas has a variety of analog switches and analog multiplexers.
Their analog switch/mux page: http://www.maxim-ic.com/products/switches/audio/

Keep in mind that if you're going to be making a PCB, you don't really have to stick with DIP packages, either - you can use surface mount packages, which will save on space. SMT/SMD can even be easier to use than thru-hole stuff; it takes a while to get used to though. One big advantage is that you don't have to drill a bunch of holes. Some of the SMT packages are pretty difficult for hobbyists to deal with though; like those that don't have leads.
 

Thread Starter

icydash

Joined Jan 14, 2009
148
You might also consider using an analog multiplexer.
Besides the industry standard 4066, Maxim/Dallas has a variety of analog switches and analog multiplexers.
Their analog switch/mux page: http://www.maxim-ic.com/products/switches/audio/

Keep in mind that if you're going to be making a PCB, you don't really have to stick with DIP packages, either - you can use surface mount packages, which will save on space. SMT/SMD can even be easier to use than thru-hole stuff; it takes a while to get used to though. One big advantage is that you don't have to drill a bunch of holes. Some of the SMT packages are pretty difficult for hobbyists to deal with though; like those that don't have leads.
Thanks for the info! Yeah I don't really have the equipment to do surface mount and my hands have never been that steady. Plus, I usually breadboard everything first and make sure it all works before making a PCB.
 

#12

Joined Nov 30, 2010
18,224
One of the best parts of an opto-isolator is isolating the noisy logic signal from the music signal. They actually brag about how well they do that after work when they're having some beers and unwinding. They are plenty fast enough for this job, but they don't have audio amps in them. They can only be used for the logic signal. However, I don't think you'll need opto's.

I have attached a datasheet for a through-hole analog switch chip, but I gotta tell you, its time consuming to search for these things. They come in single pole double throw, too. Under "multiplexer" you'll find things like 8 pole single throw.

So...what you do is make a pencil drawing of what gets switched to where, insert analog switches in the drawing, and figure out which pin to send your microprocessor signal to by looking at the datasheet.
 

Thread Starter

icydash

Joined Jan 14, 2009
148
One of the best parts of an opto-isolator is isolating the noisy logic signal from the music signal. They actually brag about how well they do that after work when they're having some beers and unwinding. They are plenty fast enough for this job, but they don't have audio amps in them. They can only be used for the logic signal. However, I don't think you'll need opto's.

I have attached a datasheet for a through-hole analog switch chip, but I gotta tell you, its time consuming to search for these things. They come in single pole double throw, too. Under "multiplexer" you'll find things like 8 pole single throw.

So...what you do is make a pencil drawing of what gets switched to where, insert analog switches in the drawing, and figure out which pin to send your microprocessor signal to by looking at the datasheet.
Thanks for this information, but I can't seem to see your attachments. Where are they?

It sounds like you're saying I don't really need the opto's, but if I was going to use them, it'd be on the control signal coming from the microcontroller controlling the switch.
 

#12

Joined Nov 30, 2010
18,224
Oops. I forgot to upload. I think one of these is a duplicate of one that is already in this thread. I already labeled them for my files so you can't see the part number until you open them. Then you can relabel them if you want to.

To answer the question, the opto-isolators would be driven by the microcontroller and their output is a DC signal, much like what the microcontroller provided. This is assuming you use an opto that has a transistor for its output stage. They also come with triacs and a few other things for their outputs. (I get this information by reading parts catalogs.)
 

Attachments

Thread Starter

icydash

Joined Jan 14, 2009
148
Oops. I forgot to upload. I think one of these is a duplicate of one that is already in this thread. I already labeled them for my files so you can't see the part number until you open them. Then you can relabel them if you want to.

To answer the question, the opto-isolators would be driven by the microcontroller and their output is a DC signal, much like what the microcontroller provided. This is assuming you use an opto that has a transistor for its output stage. They also come with triacs and a few other things for their outputs. (I get this information by reading parts catalogs.)
Thank you!
 
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