Bottlehead Forum

General Category => General Discussion => Topic started by: vetmed on June 18, 2020, 03:21:00 AM

Title: Switch confusion
Post by: vetmed on June 18, 2020, 03:21:00 AM

I am working on a preamp project and have decided that I only need 2 inputs. The Quickie used a switch to toggle between 2 inputs. When I look at the Mouser site I find it to be totally confusing, can someone suggest an appropriate part? Thanks

Robert Lees

Title: Re: Switch confusion
Post by: bernieclub on June 18, 2020, 03:50:23 AM

Probably double pole, double throw.   Search for DPDT schematic

Title: Re: Switch confusion
Post by: bernieclub on June 18, 2020, 04:01:21 AM

Maybe this...
https://www.mouser.com/ProductDetail/TE-Connectivity-PB/A201SDZQ04?qs=YCcZ0GhAU2qe09%252BfrW8Kcg%3D%3D

Title: Re: Switch confusion
Post by: Thermioniclife on June 18, 2020, 04:43:59 AM

I would recommend a 4 pole double throw, That way you can switch both the signal and the signal grounds to avoid ground loops. Just sayin.

Title: Re: Switch confusion
Post by: bernieclub on June 18, 2020, 04:57:37 AM

Yup

Title: Re: Switch confusion
Post by: Thermioniclife on June 18, 2020, 05:29:23 AM

I have used these in the past https://www.mouser.com/ProductDetail/611-7401-001

Title: Re: Switch confusion
Post by: Paul Birkeland on June 18, 2020, 05:46:36 AM

Yeah, I bet there are 5000 switches listed. 

It's really easy to get something that won't work.  Watch out for momentary switches, which means they won't stay flipped when you actuate them.  They will often look like OFF-(ON) in the listing, with the parenthesis indicating a momentary contact, but that's not always in there!

The next pitfall is what kind of terminals the switch has.  You don't want screw terminals or PC pins of any kind, so that's more sorting. 

And lastly actuator length can get you too.  I remember finding the perfect switch, then I got it and the actuator was only 1/4" long!  That reminds me, I need to throw those away...

This is the old gen 1 Quickie input switch: https://www.mouser.com/ProductDetail/Mountain-Switch/108-1MD1T1B1M1QE-EVX/?qs=/ha2pyFaduj44olDx12WvJgKiMMMtIyyIbBEor1SfF6sbsgXKL1CMY2GqkWoVPu9 (https://www.mouser.com/ProductDetail/Mountain-Switch/108-1MD1T1B1M1QE-EVX/?qs=/ha2pyFaduj44olDx12WvJgKiMMMtIyyIbBEor1SfF6sbsgXKL1CMY2GqkWoVPu9)

Title: Re: Switch confusion
Post by: Deke609 on June 18, 2020, 05:47:49 AM

Quote from: Thermioniclife on June 18, 2020, 04:43:59 AM

I would recommend a 4 pole double throw, That way you can switch both the signal and the signal grounds to avoid ground loops. Just sayin.

Lee - can you say more about this? I'm not sure I get it.

Is the purpose to allow only the grounds of the amp and source in use to be connected? If so, wouldn't 3P2T switch work? Preamp ground connected to third pole, with source 1 ground connected to corresponding throw 1 and source 2 ground connected to corresponding throw 2?

Many thanks, Derek

Title: Re: Switch confusion
Post by: Thermioniclife on June 18, 2020, 07:29:39 AM

Derek I suppose you are correct in that most source equipment has a common audio ground.

Title: Re: Switch confusion
Post by: vetmed on June 18, 2020, 08:01:45 AM

Thanks to everyone that took the time to reply, I think I will go with the Quickie switch. If it works in my Quickie it should work in my new project. Cheers!

Title: Re: Switch confusion
Post by: Deke609 on June 18, 2020, 09:13:36 AM

Quote from: Thermioniclife on June 18, 2020, 07:29:39 AM

... most source equipment has a common audio ground.

Ah, yes, I didn't even think about separate channel grounds.  That makes sense. Thanks Lee.