# 12v controller box questions

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#### grimlock3000

##### Well-Known Member
I am rebuilding my 12v launcher to meet NAR specs before I continue testing it and then go fly rockets. I have a 1/4 audio jack for the safety and now I have a 12v LED with a built in resistor that I am going to be using for the continuity check. It has a red and a black wire, and only works when plugged into the corresponding red/black on my 12v source.

Do I wire it like this...

12v source -> safety -> red wire -> led -> black wire -> igniter -> BACK TO 12V SOURCE (I presume this is the right one)

or

12v source -> safety -> black wire -> led -> red wire -> igniter -> BACK TO 12V SOURCE

The launch button will be wire in parrallel with the LED. I just want to double check before I mess up again EDIT, SEE BELOW FOR DIAGRAM

Also, do I have the right type of LED? This is the one I have:

The LED has a built in resistor, forwar supply current for the LED is 12mA with a max of 20mA. Thanks.

#### bobkrech

##### Well-Known Member
Red is usually the positive conection and black is usually the negative connection so your first choice should be correct.

12v source -> safety -> red wire -> led -> black wire -> igniter -> BACK TO 12V SOURCE

Bob Krech

#### grimlock3000

##### Well-Known Member
Here is what I currently have for a setup. I am leaving everything alone for a day or two until I am sure I have exactly what I need:

This is the box everything is in:

This is the interlock key. I have the contacts soldered together inside the top to complete the circuit:

And the interlock holder. The online pic is wrong for this, the real thing has only two contacts for a mono plug):

My continuity check LED. The one I have is the same part but it list the power draw as 12mA on the package:

And finally the momentary launch button:

I am also whonder how I can use a Piezo buzzer along with my LED as another way of warning people that pad it hot. Here is the buzzer I want to add:

The LED and Piezo combined should only draw an average of 17mA. Would this be fine? It would look like this when wired (thanks micromister for the original pic):

#### bobkrech

##### Well-Known Member
It's getting there.

1.) On the interlock jack, make sure that the bottom connection goes to the launch button, not the battery. In this manner, the only time you can power the launch switch is when the plug is all the way in and it will not cause a transient connection on insertion.

2.) The RadioShack.com switch you chose are rated for 3 amps. This is a very low current rating for a launch switch and it could weld itself on after several uses. All the RS momentary switches except for the one below have very low current ratings.

The automotive momentary switch http://www.radioshack.com/product.a..._name=CTLG_011_002_015_001&product_id=275-709 is a much better launch switch and is designed for 20 amps at 12 VDC. With both halfs wired in parallel it would be rated at 40 amps.

3.) 17 ma is fine for continuity current. Just remember in your design, the buzzer will sound anytime the interlock key is inserted. If you find this annoying, simply put one of your momentary switches in series with it. You can then check the continuity by pushing the momentary switch. If you hear the buzzer, you are good to go.

Bob Krech

#### grimlock3000

##### Well-Known Member
How ironic. I bought one of those Radio Shack 20A switches but decided not to use it. I managed to wire my interlock wrong too. Time to break out the soldering iron again...

The buzzer was not very loud so I left it alone. I do have some extra switches I could use with it if needed.

On another note, my soldering skills have at least tripled in the last week

#### als57

##### Well-Known Member
Originally posted by grimlock3000
How ironic. I bought one of those Radio Shack 20A switches but decided not to use it. I managed to wire my interlock wrong too. Time to break out the soldering iron again...

The buzzer was not very loud so I left it alone. I do have some extra switches I could use with it if needed.

On another note, my soldering skills have at least tripled in the last week

Controllers are fun. Spent about 10 hours soldering/assembling ones for LDRS last weekend. Probably improved my soldering skills too

Al
BRS VP
LDRS 23 Hosts

#### grimlock3000

##### Well-Known Member
One thing I need to get is a decent soldering iron. The Craftsman pencil tip iron I have is junk, I have to let it warm up for a minute or two after each solder point :kill:

#### als57

##### Well-Known Member
Originally posted by grimlock3000
One thing I need to get is a decent soldering iron. The Craftsman pencil tip iron I have is junk, I have to let it warm up for a minute or two after each solder point :kill:

Weller makes nice soldering stations ; but you wouldn't want to buy one new.

If you have a hamfest in your area ; check out the flea market. Often you can find Weller controller temp stations for $40 to$60 ; much better than the \$150 plus the normally sell for.

Al

#### grimlock3000

##### Well-Known Member
I have been eyeballing a Weller or Hakko soldering station for a long time I could use one for my RC stuff and various projects around the house. In the last few years, I have gone though three cheap soldering irons. Whenever I have a project to do, I just go for a cheap iron and hope it will be better than the last cheap iron. I just need to suck it up and spend some money for a good soldering station. Without the wife asking about it

If anyone wants to see how my 12v controller ended up, check the thread here:

#### als57

##### Well-Known Member
Originally posted by grimlock3000

If anyone wants to see how my 12v controller ended up, check the thread here:

Good luck on that!

Looks like a nice simple design.

I just finished up doing a couple 24 channel controllers for LDRS. Maybe if I get a chance I'll take some pics. Not inexpensive at all. The controllers and relayers are built in Pelican instrument/camera cases.

Al
BRS VP
LDRS 23 Hosts

#### bobkrech

##### Well-Known Member
If you don't like to solder, you can use automotive stitches, lamps and relays suitable for push-on crimp connectors. While these components such as the RS automotive switch I mentioned earlier have posts with holes that you can solder you wires to, it's a lot simpler to use push-on crimp connectors.

For example of the connectors look at

They come in a several widths, typically 1/8", 3/16" and 1/4", and in each width there are several varieties for different wire sizes, typically 12-16, 18-22, etc., so you have to select the right ones.

Crimping tools are pretty cheap as are the push-on crimp connectors, and a lot cheaper than a good soldering iron.

If you make a wiring mistake, you can simply pull off the wrong terminal and put it on the right terminal.

They handle a good bit of current as well. Many accessories in your car draw 10 to 20 amps of current, so they have a low contact resistance.

You will find a better selection of automotive type stuff at http://www.allelectronics.com/ than at RS.

Bob Krech

##### Well-Known Member
the wiring diagrams always show the ground going straight through and not connecting to any switches? the led's have a ground and a red? the switches all have a ground in the middle and then two "on" posts. do these not need grounds? does the led light up just passing through the positive current?

like this one:

##### Well-Known Member
i know this is a super crude drawing, but can anyone tell me how to wire this, please. i'm getting botched up on the LED. if someone can photoshop something like this i'll attach a blank. sorry, i'm really an idiot when it comes to electricity! my mind just can't see what is going on......

##### Well-Known Member
sorry, the attachment....it's obviously getting late!