Rotary Switch Wiring

How do you wire a 4 prong rotary switch to an altimeter/timer that does not have switch ports?...

I'm used to the dummy proof altimeters with two "Switch" ports "+" & "-". The Perfect Flight Mini Timer only has Power & Trigger ports. Any advice would be appreciated.



Thx,
Chris

Just put it in your positive battery lead - wire from pos battery terminal to switch, wire from switch to pos terminal of timer.

1. concect the + end of the battery to the + terminal on the altimeter
2. connect the - end of the battery to one of the switch terminals (might have to experiment to find the right one)
3. connect the other end of the switch (again, you'll have to experiment to find this terminal) to the - terminal on the altimeter.

On my rotary it was the first two leads going clockwise. The order on the switch doesn't matter, but I wired - battery to first terminal on switch and the second terminal on switch went to the altimeter.

Here's a link to my "web resident" rotary switch wiring diagram:
https://www.missileworks.com/app/download/931633604/SW-2_contacts.jpg

Thanks Guys - very helpful!!!

dward said:

1. concect the + end of the battery to the + terminal on the altimeter
2. connect the - end of the battery to one of the switch terminals (might have to experiment to find the right one)
3. connect the other end of the switch (again, you'll have to experiment to find this terminal) to the - terminal on the altimeter.

On my rotary it was the first two leads going clockwise. The order on the switch doesn't matter, but I wired - battery to first terminal on switch and the second terminal on switch went to the altimeter.

Click to expand...

just a question, wouldn't you want to cut the power + before it got to the altimeter and "switch" the power on or off, not cut the ground? in everything else i have seen with DC power for safety you want to switch positive power.

accpool said:

just a question, wouldn't you want to cut the power + before it got to the altimeter and "switch" the power on or off, not cut the ground? in everything else i have seen with DC power for safety you want to switch positive power.

Click to expand...

My question too.

accpool said:

just a question, wouldn't you want to cut the power + before it got to the altimeter and "switch" the power on or off, not cut the ground? in everything else i have seen with DC power for safety you want to switch positive power.

Click to expand...

So, are you suggesting the following configuration?...
1. connect the - end of the battery directly to the - terminal on the altimeter
2. connect the + end of the battery to one of the switch terminals
3. connect the other end of the switch to the + terminal on the altimeter.

If you don't have a multimeter, there is a graphic on our website (www.doghouserocketry.com) on the "switches" page that shows which pins on the rotary switch to connect to for single pole, single throw operation.

Bill

csoechtig said:

So, are you suggesting the following configuration?...
1. connect the - end of the battery directly to the - terminal on the altimeter
2. connect the + end of the battery to one of the switch terminals
3. connect the other end of the switch to the + terminal on the altimeter.

Click to expand...

that is how i wire all DC switches. it might not be correct but has worked for me. i would also look at Bill's recommendation. i would also get a small multi-meter, you can use it for many things including checking battery voltage to make sure you always have good batteries. get one with continuity and you can check your wiring.

accpool said:

that is how i wire all DC switches. it might not be correct but has worked for me. i would also look at Bill's recommendation. i would also get a small multi-meter, you can use it for many things including checking battery voltage to make sure you always have good batteries. get one with continuity and you can check your wiring.

Click to expand...

When you are wiring an altimeter or other DC circuit that has no connection to any other power source, then it doesn't really matter, but.... In a case when the equipment uses several DC voltage levels or even an AC source, connecting the negative as the common return/ground for all power sources is considered best practice. A PC is a good example. The - negative is the same return for all of the 3.3V, 5V & 12V power supply outputs. That would mean that "best practice" dictates that the - negative be the common return and the "power" be switched on the + side. If you really want to get down into the weeds, use a DPST switch and switch both the + and the - off to completely isolate the power source, but you might need a bleed off resister for any capacitors in the circuit if you do that.

^ you're correct. i just like to remove power from everything downstream, that way i can't accidentally touch something and short it or touch something and put power where i don't want.

I would check with altimeter/timer manufacturer for recommended switching polarity.