What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

is this switch wired correctly?

blueflyer

blueflyer

Well Known Member
I want to control the transmit function of com1 and com2 with a 4PDT switch. Do I have this switch labeled correctly for wiring? the tip and sleeve in the middle connectors go to the mic jack.

 
I cannot speak to what you are wiring, however, I believe you have identified the pins correctly. The vertical columns in this picture represents the poles. Each is switched independently. On the horizontal plan, each end terminal represents the switched component and the center is the common. Typically the pole in the plane of the lever represents the on position, but you should confirm this with an ohm meter.

The radios should be on the end terminal and the headset in the center terminal.

There are many varieties of double throw switches, such as on-on or on-off-on. If the latter, nothing is connected in the center lever position.

Larry
 
thanks larry. My line of thought here goes along with what you said, so at least I'm not completely missing the boat here. I have learned to smush a rivet adequately (most of the time), but the electronic stuff works me over.
 
Do you happen to have the part number of the switch (such as from Mouser or wherever you're buying it) so that we can look at the specs? That would help in trying to identify what the pin out should look like for your application.
 
stein air switch

its from Stein Air. http://www.steinair.com/storedetail.cfm?productid=355 Here's the description:

Miniature Toggle - 4PDT On / Off / On

Product ID: SA-818

We use these to specifically switch 2 radios in place of using a complete audio panel, or to wire your Autopilot to be controlled from 2 GPS's, etc.. You can switch up to 4 signals with this switch (We use it to switch PTT, Mic Audio, Headset Audio, etc.. or a combination thereof when a customer requests to control 2 radios without an audio panel. Also works well to switch between 2 sources for Autopilot Feeds. It's not cheap, but it's cheaper than an audio panel if you're only using a 2nd comm. Standard 1/4" mounting
 
This appears to be a Salecom T8405 switch with ON-OFF-ON configuration.

http://www.salecom.com/en/product/Toggle-Switches/t8401.html

Your proposed wiring scheme would be correct, except in the "up" switch position as oriented in your photo, the bottom two terminals on each bank would be connected. So "up" would be "com2".

I'm still not clear what you're using this for. If you're switching mic between two radios without an audio panel, you will need to use three connections - one for each terminal of the mic jack. If you're adding "push (toggle) to talk" function as well it gets a little more complicated. Also keep in mind that these switches are not "momentary" in any position, meaning unless you manually switch it to the off position after transmitting you can easily stay stuck in transmit.
 
this is how I plan to use it. I got this from Chuck over at flight data systems...I just didn't know how to hook up the switch.

 
Okay, let's start with the mike side. This is okay assuming that by 'sleve' you mean the small ring connection, just behind the tip, on the male plug. As already pointed out, 'up' will be #2. Flip the #1 and 2 connections if you want up to be #1. Also, the jack must be fastened to a good ground. Best practice is to insulate the jack and run a ground wire to your single point ground buss, but for a simple set up like this, just ground it to the metal frame and don't worry about noise.
Now the headphone side, this is wrong. You have a few options:
1. If you use stereo headphones, wire it as you show, with one radio going to the tip terminal, the other to the ring terminal. Ground the jack. You will hear one radio in one ear, the other in the other! Use the volume control to turn down the one you don't want.
2. Mono headphones. If you never want to monitor both radios at the same time, run the two radio outputs to the third pair of connections on your switch, exactly like the mike connections. Run a wire from the center terminal to the jack, ground the other side.
3. Mono headphones. If you do want to monitor both radios, wire it as shown but use the mixer. The single output goes to the headphone jack, ground the other side. Use volume controls to set levels. Note mixer has just one output, you also will need to supply ground and 12 volts to the mixer.
 
I should have mentioned, if you have no other audio you wish to hear, you can probably use option 3 but replace the mixer with two, 300 ohm resistors. One resistor in each line, the other ends tied together and a single wire to the jack. I say probably because this will reduce the volumes, so if you already need them at maximum then it won't be loud enough. This is unusual, though, most radios have plenty of volume.
This is what I would do (again assuming there is no music, no alarms, no intercom, etc).
 
BobTurner said:
Okay, let's start with the mike side. This is okay assuming that by 'sleve' you mean the small ring connection, just behind the tip, on the male plug. As already pointed out, 'up' will be #2. Flip the #1 and 2 connections if you want up to be #1. Also, the jack must be fastened to a good ground. Best practice is to insulate the jack and run a ground wire to your single point ground buss, but for a simple set up like this, just ground it to the metal frame and don't worry about noise.
Now the headphone side, this is wrong. You have a few options:
1. If you use stereo headphones, wire it as you show, with one radio going to the tip terminal, the other to the ring terminal. Ground the jack. You will hear one radio in one ear, the other in the other! Use the volume control to turn down the one you don't want.
2. Mono headphones. If you never want to monitor both radios at the same time, run the two radio outputs to the third pair of connections on your switch, exactly like the mike connections. Run a wire from the center terminal to the jack, ground the other side.
3. Mono headphones. If you do want to monitor both radios, wire it as shown but use the mixer. The single output goes to the headphone jack, ground the other side. Use volume controls to set levels. Note mixer has just one output, you also will need to supply ground and 12 volts to the mixer.
Click to expand...

Bob
I appreciate your input. It does help me thinking through this stuff. I have 2 comms, 2 navs, D100, and D120 that I want to get audio into my headset.
1. don't have stereo phones
2. i do have mono phones, but I do want to monitor both radios
3. sounds like Im onto a winner with #3. this is what I'll do. thank you for your input.
 
PMA4000

Had you considered www.ps-engineering.com/pma4000.shtml

It will also solve isolation issues so you can listen to one or all four of your audio inputs at a time.

Great IntelliVox intercom with music, and a speaker amplifier.

The units sells for $775 and probably be a great investment to your avionics suite.

It is just a little bigger than an intercom.

Mark Scheuer
PS Engineering
 
Hey mark, I did consider that one. it looks good and I like it, but I just ended up going with the audio mixer to save a little money. hopefully it wont come back to bite me.
 
You must log in or register to reply here.
Back
Top