Very newbie question about GND and resistors

Hardware questions and issues with the FV-1

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robman84
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Joined: Sun Dec 20, 2009 9:57 am

Very newbie question about GND and resistors

Post by robman84 »

Hi, apologies for the very newbie question but I bought a mixer that uses the FV-1 chip. I'd like to use the internal programs of the FV-1 and have managed to hook up a switch to T0 to enable switching between them. However for program select the mixer only uses S0, with S1 and S2 tied directly to GND, so that limits to only two programs. I'd like to use an 8-way rotary switch and hook it up to S0, S1 and S2. I've managed to use it on S0, but not S1 and S2 yet.

In all of the diagrams I've seen that use an 8-way switch there are 20k resistors to GND, but on the FV-1 datasheet the resistors are on the 3.3v line with switches to GND. Is it possible to put the 20k resistors on the 3.3v line before S0, S1 and S2 instead, if I'm using an 8-way switch?

Hope I don't come across as daft! And thanks for creating such a great chip!

Rob
frank
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Post by frank »

When you say 8-way switch, do you mean an 8-position encoder or a SP8T switch?

In general you could put the resistors to +3.3, but a schematic and part number for the switch would help give a better answer.

Which mixer is it? Would like to see one.
Frank Thomson
Experimental Noize
robman84
Posts: 3
Joined: Sun Dec 20, 2009 9:57 am

Post by robman84 »

Hi, thanks for the quick response!

It is a BCD rotary encoder that for some reason goes from 0-9!
http://www.maplin.co.uk/module.aspx?moduleno=2438

The mixer is a Sergio iSpin: http://www.sergiospin.com/iSpin.htm

I'm also replacing the centre spinner (an encoder of some kind) with a rotary pot to enable full control over the effect parameters.

I know it's not really meant for this sort of chopping and hacking, but it's fun anyway!
frank
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Post by frank »

Interesting switch, I think it will work fine (would need to see the datasheet on it to be 100% sure but...), the S0, S1 and S2 inputs need to be taken from the end of the resistor and the switch goes from there to gnd. Basically when the switch is open the SX input is pulled high through the resistor and when the switch is closed it is pulled low through the switch.

Ahh, the ibuddy, ok. I thought you meant a line mixer, I know about the ibuddy (actually made by the Asia distributor of the FV-1).
Frank Thomson
Experimental Noize
robman84
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Joined: Sun Dec 20, 2009 9:57 am

Post by robman84 »

Thanks Frank. I'll give it a go.
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