How do you wire a normalized jack?

RobotDad · Joined: Apr 04, 2010 Posts: 10 Location: Washington

Maybe not the right forum, but it seems this is the most gnarly DIY one so feels right, Smile

And yeah, I'm fairly new at this stuff, but I've successfully made a WSG and a gristelizer so I'm ready to start building something bigger and I really want to understand how to properly normalize a jack before making my next parts order. Very Happy

First off I recognize that this must be obvious as I can't find any detailed explanations anywhere... I understand what a normalized jack is but I have no idea how they should be wired. I'm looking at 3.5mm jacks, will mono work or do I need stereo type? I'm assuming mono will work but I'm confused about exactly how the mechanism of inserting the cable changes the connection.

I see a lot of mentions of needing to carefully label a panel to remember which jacks are normalized. Are there any easy blinky alternatives? For example, would there be a simple way to wire an led to remain lit when the jack was in its normal state and turn off when a cable is inserted?

Also, does closed or open style matter? I've noticed closed seem to be cheaper, is there a disadvantage with going with that style?

slacker · Posted: Sat Aug 28, 2010 10:05 am Post subject:

For normalised jacks you need ones that have switched contacts, these have 2 contacts for each connection, so for a mono jack 2 for the tip and 2 for the sleeve. The 2 contacts are arranged so that when nothing is plugged in they connect together, when you insert the plug it breaks the connection and the jack works just like an ordinary one.

These are often referred to as switched or normally closed jacks, like these for example http://www.rapidonline.com/Cables-Connectors/Connectors-Audio-Video/Jack/3.5mm-Mono-PCB-jack-socket/63491

If you wanted to add a LED to indicate that the jack was normalised you could do it like this. Connect the LED and a current limiting resistor between power and the switched sleeve connection, and connect the other sleeve connection to ground. When nothing is plugged in the LED is connected to ground so it will light up and when you plug a jack in you break the connection and the LED goes off.

RobotDad · Joined: Apr 04, 2010 Posts: 10 Location: Washington

Thanks!

Good explanation and knowing the proper term is a big help. I found little hunting on normalized, but switched gives a lot more results. These two pages were pretty good in terms of showing the schematic/picture of how these work.
http://www.prestonelectronics.com/audio2/ttip/problemjack.shtml
http://www.neutrik.com/content/technicalsupport/faq.aspx?faqId=205_747846926

Now I just need to decide if I stick with 3.5 or go 1/4 instead. Better manufacturers like Neutik and Switchcraft seem to only supplt 1/4 (Cliff isn't readily available from US suppliers that I saw). Or I may just give up on normalizing anything and just go (with) bananas.

blue hell