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Help me to make 3 channel selector for audio applications

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nikifena

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Hi guys, I must make 3 channel selector for audio aplications. The idea is when press button 1, some relay must be worked, to comutate signal via some transistor, when press button 2 another relay must be worked.
I write tihs post to see your offer. At this moment I found this two ideas:
http://www.geofex.com/Article_Folders/fxswitchr/fxswitchr.htm
whit 74c317
and
**broken link removed**

Any other ideas ? :)

Thanks
 

bbarney

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Re: 3 Channel selector

**broken link removed**
 

nikifena

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Re: 3 Channel selector

hm :( I don't like reset button
I like to have 3 buttons
button1, button2 and button3
and any of this button must be control one relay
button1 control relay1
button2 - relay2
and button3- relay3
 

IanP

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Re: 3 Channel selector

Here is an example of 3-way switch with relays.
This is conceptual diagram only and the construction circuit may require some additional components (Rs or Cs).
Depending on what you would likt to switch you can leave RLYs or use electronic switch such as CD4053..
 

metal

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Re: 3 Channel selector

Hello

You can use 74137, which is 3-TO-8 LINE DECODER DEMUTIPLEXER WITH ADDRESS LATCHES.

Much better than using flipflops. You can use the three inputs, to enable one output at a time.


Another idea is to use 8-to-3 line priority encoder with latched addresses too,the later is much easier and more manageable.


Regards
 

nikifena

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Re: 3 Channel selector

Hi, and hit the light !! :)
I make one board with 74137 using that scheme
http://www.geofex.com/Article_Folders/fxswitchr/fxselex7.gif
but don't work.

You can use the three inputs, to enable one output at a time
exactly this I want to make. This scheme is to make guitar switchiong controller with bypass and 2 loop channels. After coms chips I like to use relay to contro signals.

Can you draw some scheme with flipflops to show me what is the idea ?
I'm begginer with cmos chips :(

Thanks :)
 

IanP

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Re: 3 Channel selector

If you used 74137 with circuit based on 74373 it will not work at all. These two are based on completly differen principles: 137 latches address input with high level on (4), 373 latches outputs with a pulse (edge) on (11).
For 137 you have to re-design that circuit..

You can use only D0, D1 and D2 from 74373 and this should work..D1 and D2 will have relays connected, D0 is your "both off" stage (nothing connected)..
 

adidex

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Re: 3 Channel selector

Why not use an microcontroller, with 3 or 4 inputs for the pedals, and several ouputs (16 - 20) for the switches command ? You can then program several combinations of outputs for an pedal .. that way you can use a single IC and you can have alot of flexibility (you can store for example different setiings for each pedal in uC's eeprom and change them any time ...).
You should use something like an ATMega8515, you can find lots of simple programmers for it (see PonyProg for example), and it has 35 programmable I/O pins .. For an application like yous, it would be trivial to implemment the firmware ...

Adi
 

nikifena

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Re: 3 Channel selector

IanP thanks for your anser, sorry I mean that I make this circuit via this scheme (with 373, not with 137) sorry, when I write this post it was maybe to early :)
Actually I do exactly the same as this scheme and it doesn't work :(
When I press any button (for the test I use only led connected to outpit) tihs led who is on button's channel is on, but when a release button, the led is off :(


adidex I'm try to use something easy, and I begin with this idea with 74c373 and I like to make it to the end ;)
 

skydiverc

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Re: 3 Channel selector

try this
good luck
 

    nikifena

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IanP

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Re: 3 Channel selector

I used small breadboard to test this circuit and here is the result:
as it is it doesn't write Ds to Qs. Reason: on L level on pin 11=LatchEnable. Solution: connect 470Ω (or similar) resistor between pin 11 of 74373 and GND. This will shift the level on this pin close to 0V and any pulse from a switche (inverted and trough a diode) will write the Ds to Qs.

Other modification will be to add 10-100µF capacitor on one of unused inputs (same canfiguration with inverter, cap connected instead 10nF). This will reset all other Qs. Without this cap all Qs are H after power-on.

Now it works OK.
 

    nikifena

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nikifena

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Re: 3 Channel selector

Thanks guys, thanks IanP, now it's time to check my skills and your ideas ;)
I wish that this will be the last post about this controller ;)
I promise, that when I made this controller I post a picture ;)
 

nikifena

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Re: 3 Channel selector

Bad news :(
I try scheme with resistor and with with cap.
I get the following problem: a led only lights when a button is pushed and held. It goes off when the button is released. Maybe the chip does not keep the output level "LE" after releasing the button?

what can I do :( :( :(
 

IanP

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Re: 3 Channel selector

Which type of 373 did you use? 74373 , 74LS or 74HC?
 

    nikifena

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rx5

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3 Channel selector

i think i better use HC for low voltage application.. fron 3-6V.... for the C, its about 3-15V....

LS are power hungry chips..
 

nikifena

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Re: 3 Channel selector

Which type of 373 did you use? 74373 , 74LS or 74HC?
I use MC74HC373AN from motorolla

I forgot to tell you, that in this:
http://www.geofex.com/Article_Folders/fxswitchr/fxselex7.gif
schematih in unused (D) input pins is connected via somre resistor to gnd, I don't know their value, and now they are unconnected.... Maybe this is the problem ???

Thanks IanP.
 

IanP

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Re: 3 Channel selector

I tested this circuit once again and it works fine ( I used LS version).
You may leave the unused inputs unconnected or connect them directly to GND.

If you still have problems measure voltage on pin 11 (-LE). Without any key pressed you should read close to 0V. Hold a key and read again. It should be more or close to 3V, and this should be enough to latch the outputs.
I don't have here HC version, but LS works OK.
 

    nikifena

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nikifena

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Re: 3 Channel selector

This is result:
Without any key pressed LE - 230mV (this is the most offen meashured value, because this value is moved up and downo to 230mV)

On hold any key - 4.67 V
:( :(
 

nikifena

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Re: 3 Channel selector

IT'S WORKED !!!!
cool :)))
what I do: I put 10k resistor between LE and GND. This will put down potential of LE to GND before pressing any key.
Thanks for all
This is pic of my footswitch controller
 
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