Boz AP1.7 Input Selector PCB

Stones · 13th November 2006, 09:15 AM

Lady’s and Gents,

I have learned so many things from this forum and thanks to the generosity of its members (special thanks to nelson).

The attached files will help those of you looking for an input selector board for your pass preamps.

Its intention is to provide one balanced input and two single ended inputs the - inputs are shorted to Gnd during the use of the single ended inputs.

One switch toggles between these three inputs, if input one is selected then one LED is lit, two are lit for input two and three for three.

I have not built this yes so don't be surprised when I post the amendments I have etched the PCB but I am waiting for my relays to turn up prior to building it.

hifimaker · 13th November 2006, 03:30 PM

Hi Stones,

A couple of thoughts: I don't think the relay protection diodes are needed if you are driving with a ULN driver chip. Also you might want to consider a balanced Mute relay after you selection relays.

-David

Stones · 14th November 2006, 06:08 AM

Thanks David,

If you want a mute then any spare input (or connected unit with no power) is mute and if you realy realy must have a selectable mute then remove the short from SJ1 and short SJ2 this gives mute as the forth selection.

Regarding the protection diodes well it’s your choice if you bother to fit them or not.

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13th November 2006, 03:30 PM	#2
hifimaker diyAudio Member Join Date: Oct 2003 Location: San Jose	Hi Stones, A couple of thoughts: I don't think the relay protection diodes are needed if you are driving with a ULN driver chip. Also you might want to consider a balanced Mute relay after you selection relays. -David

14th November 2006, 06:08 AM	#3
Stones diyAudio Member Join Date: Jan 2004 Location: MN	Thanks David, If you want a mute then any spare input (or connected unit with no power) is mute and if you realy realy must have a selectable mute then remove the short from SJ1 and short SJ2 this gives mute as the forth selection. Regarding the protection diodes well it’s your choice if you bother to fit them or not.